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cwk 09-10-2020 02:33 PM

Converting a Diesel Pusher to ALL Electric.
 
Converting a Diesel Pusher to ALL Electric. Well, except the main engine. :D

I am remodeling our coach. Part of the remodel is redoing the 29 year old house electrical system. Or, you might even say, replacing the system.

I am currently in the design phase, and am learning as I go, so please be gentle. :flowers:

Here are some parts of the plan:

Replace propane fridge with 110V residential unit.
Replace the propane water heater with a 110V electric unit.
Remove ALL propane systems.
Add 24V radiant floor heating.
Replace FLA batteries with LiFeP04 batteries in a 24VDC configuration.
Replace the separate MSW inverter, charger, and ATS with a Victron Inverter/Charger (possibly 24V/3000W?)
Remove original 100W solar panel on roof and add more modern panels.
Add all of the necessary wiring, controls, monitors, etc. as needed for the wiring. (Leaning toward Victron components.)
Rewire the 110V so the two (2) roof heatpump units can be powered by the inverter(s).


Here is one piece of the puzzle that has me stymied. If I was installing 12VDC system, I could charge the house FLA (or AGM) batteries with the main engine alternator while driving. I have read that with lithium batteries, since they can take a high amperage charge, it is very wise to install a DC-DC (buck converter?) unit to limit the amount of current so the alternator does not overheat and self-destruct.

Is there such a unit that can limit the current and also step up the alternator's 12VDC to 24VDC to charge the 24VDC battery bank? Is called this a "buck-boost converter"?

Also, is this recommended? Or, should I rely on solar, generator, and/or shore power only to charge the house batteries and forego connecting the alternator output to the house system?



ALSO:

Thanks to paul65k and astrocamper for their descriptions of their systems. Both have been very helpful. :bow::bow:

Winemaker2 09-10-2020 04:58 PM

All I can say is WOW!
Running 2 AC/ heat pumps and radiant floor heat via 12 or 24 volts will require some batty bank!
You don't mention a generator? Or how you will power 120V water heater? If you travel most days a large engine Alt can be a help but what about days not traveling?
You don't mention climates you intend to travel / stay but did mention heat & AC both of which can be a BIG load for Betty's.
I'd suggest an energy estimate & energy balance for all systems as a starting point.

richard5933 09-10-2020 05:20 PM

You're asking for quite a bit out of your system, and you will need quite the battery bank to run it. And solar bank.

Check out this YouTube channel: https://www.youtube.com/channel/UC-x...RrOTE_74WbU5cg

It's a bus conversion, but the owners are doing exactly what you're describing. When you see the amount of solar they've installed to run the system, I suspect you'll realize it may not be as good of an idea. And, when you see the rack system they have to double their solar capacity, realize that they've just added two additional ground-deployed panels to augment the ones on the roof.

A few suggestions:

1 - Easiest way to charge your 24-volt house batteries while on the road might be to install a 24-volt high output truck alternator to your main engine. If you get one with the correct output, you might be able to run it directly to your battery bank for charging. If not, then a DC-to-DC charger would make it work. You might also be able to use it through your solar charge controller to charge the house batteries by running the output from the 24-volt alternator parallel to your solar bank into the charge controller.

2 - Consider using a diesel heater instead of all electric. Even the high-end coaches being sold which claim to be 'all electric' often use diesel heat. There's not a really good way to heat a coach off batteries for a length of time, and you don't want to leave yourself with frozen pipes should you encounter a stretch of overcast freezing weather.

3 - Redundancy is important. Even if you go with 24-volt heat, you will benefit from having a redundant heat source. Again, a week of cold cloudy weather will make you wish you had something other than solar to rely on for heat.

4 - You can get an electric water heater which also has a loop for running a coolant line through it. That allows you to make hot water from the engine heat or from something like a Webasto (diesel heater).

5 - After you watch the YouTube videos I linked to above to see the size of their solar bank, measure the roof of your coach and determine just how many watts you can safely put up there. This will largely determine much of the plan you are doing. It makes no difference how big your battery bank is if you don't have enough solar to recharge it in the time the sun shines.

6 - Do you math on hours of sun where & when you plan to be with the coach. If you are in the northern part of the country or traveling in the winter months, you're solar output will be reduced from the stated output on the panels.

It seems to me that a hybrid system is going to be the best path moving forward on this kind of thing. Relying on just one energy source leaves one open to problems. Propane has its advantages in heating a coach, but a diesel heater can replace it easily. That leaves you with only a single fuel to have to refill.

Hope this helps. Looks like a fun project.

Rocketman3 09-10-2020 11:30 PM

To charge a 24v lithium from your 12v alternator- look at Victronís Orion Dc-Dc charger. It can charge the lithiumís with the proper voltage & cutoffs.

How large of a lithium system are you thinking about? & how large of solar?

Good luck with your project

cwk 09-11-2020 11:34 AM

Thanks for all of the comments and suggestions thus far. :bow::bow::bow:

Yes, there is a diesel generator on-board. It is a 7kW Onan. Yes, Redundancy is Important. We plan to be self-sufficient (not connected with a cord) with two electric sources: solar and genny.

I did a preliminary energy audit. Not everything will be intended to run for days without running the genny or good sunshine during extremely hot or extremely cold days. The size of the battery banks and the solar would probably be unrealistic. :blink:

Some genny use is most likely expected for extra hot, sunny days when both A/C units are needed. Now that the basic decisions on power sources have been made, I need to conduct a detailed audit to determine actual components, number of panels, batteries, etc. Then, I will review my decisions again.

Water heater will probably be a 110V, 10 gallon, residential type unit. I will need to be able to drain, flush, and bypass the heater tank in case I need to winterize the coach. It may live where the original RV gas/electric heater was. Not sure yet. I would like it closer to the kitchen. Maybe in the basement where the existing gas furnaces live?

I considered adding a diesel heating system (like Aquahot or Webasto), but am still leaning toward using the heatpumps and electric radiant floor heating. And, adding some heat pads for the fresh water and waste tanks.

Additional insulation on the walls and ceiling is part of the plan to decrease the load on the heating and cooling systems.

With LiFeP04 batteries, the recharge time is much, much less than FLA or AGM. If the genny does need to be run to recharge the batteries, it will only be for an hour or two instead of possibly 6-8 hours. There are many more beneficial characteristics of LiFeP04 that make this plan feasible as well. Too many details to list here.

Thanks for the pointer to that bus remodel. They recorded a LOT of information. It will take me quite some time to review. I did see something about them using a Tesla battery. I have seen some other videos about this. I don't think I want to go that route. But, it will be interesting to learn the what's and why's.

We are not sure about where the coach may be used, but we are not planning on using it for ski trips or other winter activities. I've shoveled enough snow earlier in my lifetime, and I do not any more practice shoveling the white stuff! :nonono:


Comments are very much appreciated. A link to our coach efforts are in my signature below, if anyone is interested. It contains notes from when we purchased the coach a few years ago, including what repairs were needed along the way. It is very much a work in progress. :rolleyes:

n0arp 09-11-2020 12:10 PM

If you're doing such a retrofit, you should ditch the rooftop ACs while you're at it and replace them with mini-splits. Mine do a better job cooling (and heating, since the heat pumps work well down to the single digits) and use a third of the energy of the rooftop units they replaced. This also addresses the heat pumps you want to add, and removing them frees up additional space for solar panels, assuming you aren't already planning a raised rack to house them.

Most residential style water heater tanks are coated in ceramic or porcelain to deter rust, using one in an RV is recipe for disaster. Just stick with a simple RV water heater, and either buy one that runs on electric out of the box, or buy a 110V heater that screws into the anode port.

A pair of Victron 24/3000/70 inverters will charge the batteries at ~4kW. That means to fill a 20kWh bank discharged to 20% SoC, you will need to run your generator at least four hours - LiFePO4 banks can charge quickly, but there are other limiting factors you need to remain aware of, especially if chasing high elevation with a N/A genset (though the output of a 7K Onan at 10K' is still more than the charge rate of the mentioned pair of Victrons). If you go with a single Victron, charging will take twice as long.

I think you're on the right track avoiding Tesla or used EV cells, in general. LiFePO4 is a relatively benign chemistry and much safer for RV use.

If you go with new, name brand components you're looking at north of $20K for solar, batteries, and supporting equipment alone - assuming you don't cut corners.

Ivylog 09-11-2020 09:20 PM

OMG is as polite as I can be without getting in trouble with the moderators...again.

richard5933 09-11-2020 09:53 PM

Quote:

Originally Posted by Ivylog (Post 5436636)
OMG is as polite as I can be without getting in trouble with the moderators...again.

What are you saying "OMG" about? The concept of converting a coach to all-electric or one of the responses?

Was your "OMG" meant in a good way, as in Oh my God - That's an amazing idea? Or negatively, as in "Oh my God - why would anyone do that?"

Personally, I go with the OMG - That's an amazing idea! I truly hope that the OP succeeds with this project, learns something from it, and shares it with the rest of us so that others can make use of what he's learned and tried. Great to see people trying out their ideas in the real world, especially one that hurts no one and can lead to some novel approaches to operating an RV.

Ivylog 09-12-2020 04:39 AM

It’s hard enough to make a “all electric” coach that uses diesel/Aqua Hot for heat, rarely propane as the tank is to small, into a off the grid machine. Biggest obstacle is running the AC on batteries...yes it can be done if you throw enough money at it. Rarely are heated floors DC current...to many amps so they are 110V and used when on shore power, but if you have enough solar and batteries to run the ACs (OK, probably only one) you can heat the floors too. At least with AC you need it more during the day (sun is shining) unlike heat that’s needed more when the sun is not at a good angle or not even up.

Even though the OP is replacing his floors, putting 24V DC heating instead of 110V is foolish. I will not encourage the OP to throw $$$$ into this money pit idea in a rig that’s coming up on 30 years old. Spending more than what the rig is worth to make it worth half as much to someone else doesn’t make sense to me...sorry!

richard5933 09-12-2020 06:27 AM

Quote:

Originally Posted by Ivylog (Post 5436841)
Itís hard enough to make a ďall electricĒ coach that uses diesel/Aqua Hot for heat, rarely propane as the tank is to small, into a off the grid machine. ...

I can respect your thoughts on this. Sometimes though, people do things just to see if they can. I'm sure the OP has work to do on the budget, and it would be interesting to see if any the calculations comparing the various options on heating/cooling the coach.

jcussen 09-12-2020 10:16 AM

Know about a guy who shoehorned 3000 watts on his roof and has over 1000+ a/h's of lithium batteries. If he has some sun, he can run his air conditioners on battery only. He does have an aqua-hot for heat and hot water though. When you figure out costs of solar controllers, inverter/chargers. panels and all the other gear you will need, you will be surprised at the cost. I can run one ac for 3 or 4 hours on battery only, and did all the work myself and still have about $5000 in the electrical system, but good luck anyway.

n0arp 09-12-2020 10:35 AM

Quote:

Originally Posted by Ivylog (Post 5436841)
It’s hard enough to make a “all electric” coach that uses diesel/Aqua Hot for heat, rarely propane as the tank is to small, into a off the grid machine. Biggest obstacle is running the AC on batteries...yes it can be done if you throw enough money at it. Rarely are heated floors DC current...to many amps so they are 110V and used when on shore power, but if you have enough solar and batteries to run the ACs (OK, probably only one) you can heat the floors too. At least with AC you need it more during the day (sun is shining) unlike heat that’s needed more when the sun is not at a good angle or not even up.

Even though the OP is replacing his floors, putting 24V DC heating instead of 110V is foolish. I will not encourage the OP to throw $$$$ into this money pit idea in a rig that’s coming up on 30 years old. Spending more than what the rig is worth to make it worth half as much to someone else doesn’t make sense to me...sorry!


All of the OP's goals are well within the realm of possibility, if they are dedicated to doing it.

We have a fifth wheel, that we bought new in 2015. We're approaching the same $$ amount in mods as we spent on the rig itself, and have no regrets. We don't worry about resale value, as this is a rig we intend to travel in, maintain, and repair for the foreseeable future - rather than replacing it. We do care about insured value, which required a separate appraisal at our expense to increase the insured value - something to consider when making these sorts of changes. This is our home (we sold our house and full-time) and are very happy with our decision to spend the money to make our lives in it more enjoyable. In our case, having the rig we want easily trumps resale value on our priority list. We boondock on BLM/USFS land most of the time, spending maybe a week or so in a park every two to three months if we can't find desirable free camping near where we want to stay.

We have 3kW of solar, 22.8kWh of LiFePO4 (48V, ~1800AH@12V), 30K of mini-split HVAC and a lot of other mods. We have our mini-splits - which works better than the factory rooftop ACs ever did - controlled 24/7 via thermostat and keep the rig a constant 70 during the day and 64 at night, wherever we are -- staying in places that range from freezing during the day to over 100F. We very rarely have to run the generator and prefer it that way.

The OP isn't foolish at all if they will actually use and enjoy the work they do.

That being said, lets look at some of the figures behind it. We averaged $31.87/night in park fees (weekly or monthly discounts commonly used and included in those figures) prior to the solar/HVAC installation and now average about $10/week in dump fees. That's a savings of roughly $213.09 per week. If we spend a conservative 80% (~42 weeks) of the year boondocking instead of in parks, that saves us approximately $8949.78 per year. In a few years, that exceeds the ROI on solar. It will eventually pay off, if you use it accordingly -- if that even matters to you. That doesn't even account for the fact that we are now Thousands Trails members and most of our park time is in TT parks - parks that were mostly off the table due to 30A service before. Once our TT membership ROI is reached (around 200 nights, half of which we've already used), the savings will accumulate even quicker. We opted for TT, in part, because of the lack of boondocking up the east coast and abundance of TT parks there. The numbers are a lot more nuanced than you probably realize as an armchair observer.

Rocketman3 09-12-2020 12:16 PM

Here are some ideas I have been thinking about that may help you on your project.

Look at AM Solar they have a transfer switch you put after your inverter that lets you run your whole rig (both legs of ac) off of one inverter. ( I just saw a YouTube video by Jared ______(?) about it.

That will let me use a 5000va inverter, which should be good.to run everything ( just not all at the same time).

24v min battery - 48 would be better. I am thinking about making my own battery. Electric car parts. Com has just the cellls - then I was thinking about rec bms for the bms - because it can connect directly into all the Victron stuff ( mppt’s Cerbo GX, inverters, etc).

For the 12 v side, I was think of putting one marine battery lead acid battery. Then using a 48v or 24v to 12 volt converter to run all the 12 v stuff. If my 12 v draw was more than the converter could handle - it would pull down the 12v battery a little. This way I keep the emergency battery assist to start the chassis engine.

Heating I always figured was way to energy intensive other than using a little to supplement from excess solar.

Good luck with your project.

n0arp 09-12-2020 03:04 PM

Quote:

Originally Posted by Rocketman3 (Post 5437319)
Here are some ideas I have been thinking about that may help you on your project.

Look at AM Solar they have a transfer switch you put after your inverter that lets you run your whole rig (both legs of ac) off of one inverter. ( I just saw a YouTube video by Jared ______(?) about it.

That will let me use a 5000va inverter, which should be good.to run everything ( just not all at the same time).

I know of more than a few failures from other message boards, and helped one guy we were camping with bypass his when it failed. They seem to have a pretty high failure rate and AM Solar's marketing/misinformation regarding Victron equipment has lost me as a customer forever.

You can use a Victron Autotransformer to step up 120V output from a single inverter to true split phase 240V - a better solution than AM Solar's or a NO/NC switch. Or running two inverters isn't really an issue, and you can use an Autotransformer to load balance your 120V loads across both inverters, so you never have to worry about overloading a single inverter and can even access the capacity of both inverters on a single leg.

Quote:

Originally Posted by Rocketman3 (Post 5437319)
24v min battery - 48 would be better. I am thinking about making my own battery. Electric car parts. Com has just the cellls - then I was thinking about rec bms for the bms - because it can connect directly into all the Victron stuff ( mpptís Cerbo GX, inverters, etc).

Know what you are getting into with used EV cells. Aside from the chemistry associated risks, you will find that you are limited in your ability to discharge the cells fully -- with Leaf cells, for example, the low voltage cutoff for a 24V Victron inverter will trigger when you still have something like 20% SoC. Or maybe that was with Tesla cells - whatever the case, both have similar issues, the numbers are just slightly different and I would have to go refresh my memory to give you the exact figures. With a 5.3kWh Tesla cell you end up losing almost 1kWh of capacity because you can't access the bottom and can't charge them to the top. A DIY LiFePO4 bank would be a better option and probably not a whole lot more expensive if you source the cells directly from overseas manufacturers.

Quote:

Originally Posted by Rocketman3 (Post 5437319)
For the 12 v side, I was think of putting one marine battery lead acid battery. Then using a 48v or 24v to 12 volt converter to run all the 12 v stuff. If my 12 v draw was more than the converter could handle - it would pull down the 12v battery a little. This way I keep the emergency battery assist to start the chassis engine.

I have a pair of Victron Orion 30A DC-DC converters providing a constant float voltage to a standard RV/Marine battery for my 12V system - exactly what you are describing. It works perfectly.

Quote:

Originally Posted by Rocketman3 (Post 5437319)
Heating I always figured was way to energy intensive other than using a little to supplement from excess solar.

We usually let our mini-splits handle the heating of the rig, and that works great.

Ivylog 09-12-2020 06:33 PM

Quote:

Originally Posted by richard5933 (Post 5436875)
I can respect your thoughts on this. Sometimes though, people do things just to see if they can.

I resemble that having done a DIY 1000W of solar that will never pay for itself because we only use it 40-50 days /summer as half timers.

sibe 09-13-2020 05:16 PM

I am no expert in this solar field but have spend hours researching, some for just basic chging the RV but then for my country house since I positioned it to grab 70-80% of the days sun... mainly as it was a winter getaway and spent money on windows that help letting heat in during winter and hot out in summer.. they help.. Anyway Solar is being looked at for 2022 or 2023..

Back to RV.. since this a refit.. or remodel.. and assume no propane as it is another thing to fill.... etc,, diesel to run rig and genny...

1.. mention to charge off altenator.. IMO add an altenator only to charge battery bank as you can purpose as 12v or 24v, still need regulation for litium.. since a simple 12 v that can kick up 15v is limited on watts if you start trying to step up to 24v to charge, one or other has to give...physics

The Geny is going to run a 110v charger to you are fine..

2. Power management system a must for shedding the AC load,, you start adding up 2 splits, elect water, battery charging, cooking....plus other items you fire up... the amps go up fast..

3. new AC as mini splits are more efficient meaning less watts to cool...

4. one thing not mentioned , insulated windows and more insulated in the Rv itself... Not sure how deep you are digging in but RV are energy, heat, cooling Loss monsters..

Just adding 2 heavy coats of a roof sealant / white refective on my cream colored fiberglass made a 8 degree avg drop using a infred heat reader .. blah blah.. and yes you are adding solar to cover but it can help IMO..

Goodluck and have fun .. RVing is work but rewarding..

jcussen 09-13-2020 07:39 PM

I use this to supply 120/240 on my home system. Not big enough to power everything though.
https://www.solar-electric.com/maenm...4aArxoEALw_wcB

sibe 09-14-2020 05:42 AM

I quess my brain is spit by the use of 220v,, Yes a 50amp RV is technically 220, 50Amp each but the RV rarely uses native 220, some newer may have clothes dryer or water heater.. BUT when generating power by a generator or solor ..it is about watts and total watts..

One inverter and an isolating/auto transformer can split the legs to act as an edison 3wire but.. it is still cabout watts/volts/...

AS I mentioned add up the total watts of what you wish to use at one time in your Rv and design the system from there..
even load moniters that distribute load still only have "X" watts to share and flip, like turn off hot water while 2nd AC runs etc etc.. Sure some can also fire up genny to help feed the demand for a bit... not sure if all that is part of the OP master plan..

Even the spit AC units, run on 110 or 220.. It will be 1500 watts 12.5 or 6.25 A.. or atleast 125A at 12v..

Wire sizing will become the an important part of this design...

richard5933 09-14-2020 06:58 AM

Seems like having two inverters run parallel to provide 120/240 would have at least two advantages:

1) You've got the option to run 240 mini splits, meaning that you can use one variable outside unit to run two indoor units.

and

2) Two inverters will mean smaller gauge wires between the inverters and batteries. This will make it easier to run the wires, and it will make it easier to reduce voltage drop. One large inverter will be nearly maxing out 4/0 wires when pulling full load.

Rocketman3 09-14-2020 11:46 PM

One of the issues with trying to run 240v on our motor homes is you have to engineer in it only getting 110v.
When you hook up to a 50 amp power you get 2 legs at 50 amps each but 180 degrees out of phase - so you have access to 220 volts.
But when I plug into a 30 amp, 20 amp or start my Onan QD7500 I get either 30 amps (total) on both legs in phase or 20 amps total in phase or in the case of my generator 35 amps in each leg but they are all in phase so not 220v
So you need to either use all 110v stuff or spend a lot of time and engineering to get the 220v stuff so you don’t blow it up.

richard5933 09-15-2020 01:37 AM

Quote:

Originally Posted by Rocketman3 (Post 5441059)
One of the issues with trying to run 240v on our motor homes is you have to engineer in it only getting 110v.
When you hook up to a 50 amp power you get 2 legs at 50 amps each but 180 degrees out of phase - so you have access to 220 volts.
But when I plug into a 30 amp, 20 amp or start my Onan QD7500 I get either 30 amps (total) on both legs in phase or 20 amps total in phase or in the case of my generator 35 amps in each leg but they are all in phase so not 220v
So you need to either use all 110v stuff or spend a lot of time and engineering to get the 220v stuff so you donít blow it up.

Our first coach had 240v appliances. Some of the current coach being sold have 240v as well. You are correct, that those appliances will not work when plugged into 30-amp pedestals.

Here we are talking about a situation where someone is building a coach which will be able to largely run off batteries and not rely on the pedestal. It would be fairly simple to wire in 240v circuits to run things like mini-split a/c units off inverters. For times when the coach is plugged in, the 240v circuits can still be run off the inverters and the pedestal's job would be to power the battery charging side of the inverters. That would of course be power from the circuits energized by a 30-amp pedestal.

Ivylog 09-15-2020 05:24 AM

Quote:

Originally Posted by richard5933 (Post 5439735)
Seems like having two inverters run parallel to provide 120/240 would have at least two advantages:

1) You've got the option to run 240 mini splits, meaning that you can use one variable outside unit to run two indoor units.

Might want to read up on how 240V works. You’re 240V will not be 180 out of phase to run a motor.

sibe 09-15-2020 05:28 AM

Stacking inverters that have sync capibilites will give you the 220-240 but be aware of possible nuetral unbalance , Land both nuetrals on the panel, do not comon them and run one of the same guage as the L1/L2 wires..

info here

I dont think anything in the RV will need very heavy wire/romex . on the 110 side .. short runs , branch ciruits, 20amp max , watter heater, to the splits..

the big wire will be in the solar and batteries, chargeing etc.. Soloar panels/collection wires need to be hefty.. 8-6 to even 4 guage depending on configure,, 12v voltage loss adds up fast.. and solar depends on efficiency..

richard5933 09-15-2020 07:08 AM

Quote:

Originally Posted by Ivylog (Post 5441164)
Might want to read up on how 240V works. You’re 240V will not be 180 out of phase to run a motor.

I'm aware of how 240v works. You might want to read up on stacking inverters.

I did mistakenly say the inverters would be parallel - I meant in series.

Here is one inverter/charger that has the capability to be stacked and to run 240v appliances.

Inverter Charger | Freedom SW 24V 3012 Inverter/Charger | Xantrex

n0arp 09-15-2020 08:41 AM

1 Attachment(s)
You can use an Autotransformer to load balance the 120V loads across two stacked inverters configured for 240V split phase output.

Attachment 301135

I can put a 3kW load on either L1 or L2, and both inverters will see a 1.5kW load +/- <1%. The only limitation is that the imbalance can't be greater than 32A, which is roughly 3.8kW - which I've never seen in my rig in practice, using all electricity without any regard for the limitation.

Similarly, you can also use one to step up 120V sources to 240V split phase.

I have two in my system - one to load balance, and one to step up 120V sources to 240V split phase so that my stacked inverters programmed for ESS will not reject the input. They're incredibly efficient and negate most of the concerns in the last few posts here. I have both my Onan 5500LP and a dedicated 30A inlet wired to a transfer switch, with the output of the transfer switch feeding an Autotransformer wired to output 240V split phase, which then feeds 120V out of phase to each of my inverters on AC2. The factory 50A inlet feeds AC1. Both feeds run through hardwired Progressive EMS devices before the inverters - something worth mentioning since we're talking about potentially expensive equipment here.

You could even just put one between the HVAC breaker and disconnect box. It's an elegant, efficient solution to the 240V load with 120V input problem here.

You can also use them with a 240V single phase inverter, to get 120V out of it.

jcussen 09-15-2020 10:51 AM

Needs 48 volt input, but this single inverter supplies 120 and 240. If I needed more than 4400 watts, couldn't I just parallel or stack them?
What am I missing?
https://www.solar-electric.com/maenm...xoC1GIQAvD_BwE

n0arp 09-15-2020 03:39 PM

Quote:

Originally Posted by jcussen (Post 5441521)
Needs 48 volt input, but this single inverter supplies 120 and 240. If I needed more than 4400 watts, couldn't I just parallel or stack them?
What am I missing?
https://www.solar-electric.com/maenm...xoC1GIQAvD_BwE

The transfer switch is only 30A per leg, and that's just the first thing I saw on the DS.

jcussen 09-15-2020 03:55 PM

Quote:

Originally Posted by n0arp (Post 5441772)
The transfer switch is only 30A per leg, and that's just the first thing I saw on the DS.

So, if I needed more than 30 amps per leg, could I just parallel a second unit? Right now am nowhere needing that much current.

n0arp 09-15-2020 07:33 PM

Quote:

Originally Posted by jcussen (Post 5441789)
So, if I needed more than 30 amps per leg, could I just parallel a second unit? Right now am nowhere needing that much current.


You could, but then you are back to two units. Why not go stacked Victrons then?

Regardless, without at least two, you're downgrading your 100A service (50A x 2 legs) to 60A (30A x 2 legs) - not the brightest idea, even if you don't think you will be using more than 30A per leg.

I don't see what problem you are trying to fix with this, unless the sole motivation here is to save a few hundred dollars in what, in the grand scheme of things, is a several thousand dollar system you only want to have to buy once and have no regrets about.

jcussen 09-15-2020 08:13 PM

Quote:

Originally Posted by n0arp (Post 5442046)
You could, but then you are back to two units. Why not go stacked Victrons then?

Regardless, without at least two, you're downgrading your 100A service (50A x 2 legs) to 60A (30A x 2 legs) - not the brightest idea, even if you don't think you will be using more than 30A per leg.

I don't see what problem you are trying to fix with this, unless the sole motivation here is to save a few hundred dollars in what, in the grand scheme of things, is a several thousand dollar system you only want to have to buy once and have no regrets about.

Because I already have the Magnum, certainly not going to scrape it and buy two Victrons. I don't have to worry about pass through and shore power at all because all my power is produced by solar and batteries. If I do upgrade, I will run another Magnum in parallel, but thank you for your constructive criticism.

n0arp 09-15-2020 08:49 PM

Quote:

Originally Posted by jcussen (Post 5442095)
Because I already have the Magnum, certainly not going to scrape it and buy two Victrons. I don't have to worry about pass through and shore power at all because all my power is produced by solar and batteries. If I do upgrade, I will run another Magnum in parallel, but thank you for your constructive criticism.

If you already have it, and it is working for you, then I agree, it certainly makes the most sense to keep it.

cwk 09-18-2020 12:35 PM

All-Electric Plan Update
 
OP here.

I have made some preliminary decisions, and am still researching and reading your comments. Thank you. :bow:

Please let me share what I have so far. And, this is subject to change. :whistling:

Battery Bank: 12VDC LiFeP04 batteries in a 24VDC configuration. Number of batteries will depend on results of electrical usage survey.

HVAC: Taking a very serious look at a two-zone 18-24K BTU minisplit with a small Indoor unit in the bedroom and a larger Indoor unit in the center of the coach facing forward. That still leaves the bathroom (the floor plan is a side hallway with a completely closed bathroom; not a walk-through bath). The Outdoor unit would go in one of the basement bays; possibly the one where the current gas furnaces live. There are 120VAC mini-splits, but they have smaller BTU's and that would require two complete installations for the coach. The larger Outdoor units require 240VAC.

Finding locations for the Indoor Units is a bit of a challenge. Since I am removing/redesigning/replacing most of the cabinetry, etc. anyway, I can redesign as needed. The installation manuals for some of the Indoor Units are helpful. Online youtube installation videos seem to be helpful as well. (What did we ever do before the Internet? :whistling: )

Remove the new Coleman heatpump from the roof up front.

Remove the original Coleman A/C from the roof over the bedroom. (It still runs, including the heat strip.)


Floor Heat: Looking at a 120VAC mat system to be installed over the existing 3/4" marine plywood floor. Then, probably engineered wood, or some type of vinyl flooring (no carpet). DW is still in the interior design phase. I priced a 24V mat system from one supplier. The price was about 5K, just for the parts. I would be providing the labor, but I still thought this was high. 120VAC pricing appears to be much more reasonable.


240VAC: This is needed for the above mini-split. Victron apparently makes an inverter/charger model so that two of them can be connected to supply 240VAC.

The existing generator will provide 120VAC to the two inverter/chargers.

Shore Power will provide 120VAC to the two inverter/chargers.

Victron apparently makes a unit that will convert 24VDC to 12VDC so I can power all of the 12VDC house items: water pump, lighting, etc.

A couple of you suggested using the 12VDC output from the system to supply 12VDC to the House lighting, etc. AND keep a 12VDC battery charged. I am not quite sure why this is that beneficial. I guess if the Inverters go offline I could still have lights and a water pump? Powered by the 12V battery?

I am considering NOT connecting the main engine alternator output to the House system. In fact, I think I want to completely separate the Chassis and House systems at all times. The only time I may need to connect them is if the Chassis batteries die and I need to start the main engine. Others have said a temporary connection with Jumper Cables will do the trick until Emergency Repairs can be completed.


Solar will provide some high voltage power to one or more MPPT controllers to charge the batteries. Not sure where they are connected yet, but will learn that once I start the electrical schematics. :D


This is a work in progress. No physical work on the new electrical system has started. I have removed the propane range, propane fridge, incandescent lighting, fluorescent lighting, and a few other things. I have temporarily installed new LED ceiling lights. I have removed a lot of the cabinetry, jack-knife sofa, carpeting, etc. Next, I will be working on removing the gas lines, propane tank, some skylights, etc. as I continue to plan the new electrical system.

The comments so far have been extremely helpful. Both what to do, and what not to do. Thank you!!! :bow::bow::bow:

richard5933 09-18-2020 08:18 PM

Sounds like a great start to the planning process.

One suggestion would be to explore battery-to-battery chargers. We have a 24v chassis system and a 12v house system. I wanted a way to charge the house batteries from the engine alternator - redundancy and convenience. Let's us charge the house while driving when the generator is not needed. We arrive in campground with full batteries all around.

We use one of these: Sterling Power battery to battery charging system - DC to DC smart battery charger, marine grade DC powered charger 24v to 12v

It's a true smart charger, and it keeps the two systems totally separated. They make them in all kinds of configurations and I'm sure you can find one to work if you want.

I wired ours so that the battery-to-battery works only when I flip a toggle and that allows me to have total control of where the battery charge comes from.

sibe 09-19-2020 07:02 AM

cool.... the battery to battery chg may be a good addon, since even with the solar you can back charge chassis if you feel the need.. LOL

With all the electric heat, floors and splits, 220V will save on wire size, splits have the same effiency on 110 or 220 with inverter technology. ..watts are watts. btu=watts is a constant..
Depending on the design, space etc. maybe 2 single splits may work ..to get them where you want or the cartridge system instead of the long wall mount indoor. not sure on what you plan on remodel.

I can see a 10K genny and a full roof of solar with maybe a remote add on with all this you are planning.. LOL building a rv castle so live like a king..

R Cabesa 09-20-2020 09:38 AM

What floor heat are you looking at?



If it is something like "Warm Floor" it is really not made for space heating, just taking the chill off the floor.

glennwest 09-20-2020 11:50 AM

Quote:

Originally Posted by n0arp (Post 5442148)
If you already have it, and it is working for you, then I agree, it certainly makes the most sense to keep it.

In my research Victron only goes to 3k with the mulitplus. Have to go to quatto for anything higher. Two quattro are costly. Two Magnum 4200 watt lots less money and solid inverters. And two magnum you get 60 amps

n0arp 09-20-2020 05:01 PM

Quote:

Originally Posted by glennwest (Post 5448093)
In my research Victron only goes to 3k with the mulitplus. Have to go to quatto for anything higher. Two quattro are costly. Two Magnum 4200 watt lots less money and solid inverters. And two magnum you get 60 amps

There are several features that Victron offers that Magnum doesn't (ESS, DVCC, VRM, etc), that are compelling reasons for a lot of users to spend the extra money.

You and I discussed some of these in depth on one of the FB solar forums several months ago, so I know you're aware of them.

If the additional features don't justify the costs, or footprint in your case, you are free to buy whatever fits your budget and location.

Krbjmpr 09-20-2020 07:41 PM

TL:DR
Very Long Post. Personal experiences and suggestions that likely have been mentioned already.


For the fridge, rather than replace in entirety, I would change cooling unit for a compressor based cooling unit. Run on 12vdc or 120vac.


Swapping out LP water heater for a typical electric one will penalize you by losing ability to heat water using engine. There are electric models available that have a second heating loop built inside. Most are described as hot water storage tank for solar and usually geature a single heating element as well. There are also external heat exchangers that setup a thermosiphon inside the water heater. Externals are also somewhat common in solar catalogs.


Radiant floor heating is wonderful if using mats. Pretty good using strips as well. If you are considering strips, might also think about running a few loops of pex in each room. Then circulate engine coolant from the DP or Generator to gain heat.



Remove all LP... You might be passing up an opportunity here, especially with an old deisel. I added propane injection to a nearly wore out C7 Ascert. Climbed hills very easily afterwards. A few gallons will last a LONG time. Propane is similar to a diesel as nitrous is to gasoline except your limiting factor is exhaist gas temps. Research it.


Victron systems are spectacular but expensive but highly customizable and modular. Consider 48vdc battery bank.


48v loads have only a quarter of the current draw that a 12v loads do. 48v has half the current draw that 24v loads do. I suspect you will find more availability, system component wise, in 48v than 24v configurations. Especially for inverters.


If your motorhome has basement air, you are golden for using mini-split air conditioners. There are several "off brands" that are 24v and 48v solar ready. No AC power connections. Research them, especially in solar catalogs.


There are also dc rooftop air conditioners from King Solar (I think). I have not used them but have had an interest. Unfortunately, their published data didnt add up when looking at compressor specs.


Saw a youtube video about a guy that built his own camper (goes ON a pickup). His solar panels extended outward when he was parked. I have seen flexivle panels sewn into awning fabrics. Not sure about long term durability. Owner was clueless - "it just works" was common response.


Personally, I would keep the generator in place until you work out the bugs in your new alternative energy system. You may find that you absolutely dont need it anymore. You may find that you need it to charge batteries. You might even find it useful for when batyery bank is dead. In the latter scenario, you can remove the genset to install a larger / more batteries. Or use it for storing everything else the family cant do without but wont fit anywhere else. If generator weight is removed, the front suspension may need to be changed as well. Same goes for adding additional weight.



Large engine alternstors are typically available in 12 or 24v. I happen to know that Neece alternators are available in 12, 24, and 48v. You can always knock down voltage (and gain current capacity increase) to 12vdc for coach and driving electronics. Keep coach and driving separate. It is harder / less efficient to boost voltage (and lose current capacity).


Lothium can *tolerate* a high current to charge with. What is most important is that charge voltage does not exceed specs of your cells / bank. They can be charged at a lower current, voltage will drop accordingly but will rise again. You absolutely want the Lithium Phosphate chemistry. Much safer (compared to others), better temperature range, bit at a cost of reduced cell voltage and hence Watt-hour capacity.


A Boost regulator takes a lower voltahe and raises it.
A Buck regulator takes higher voltage and reduces it.
A Buck-Boost regulator is able tobgo either way, but you trade efficiency on both modes to gain capability with both modes.



If I remember correctly, Victron has a boost regulator available as a custom design. Not only is it able to charge multiple chemistries, bit it is also able to share with rest of Victron system.


A few personal keypoints...
Rewire lights for own circuits. Run with higher voltage LEDs. Harder to find, but much closer to residential.


Use multiple 24/48vdc to 12vdc BUCK regulators in your load center for dc loads. It is much better to lose a single converter than to lose all of your DC capability. Besides, as current capacity goes up, efficiency will decrease and standby losses will increase. Matching a converter to a load with reasonable overhead is more efficient and sometimes cheaper.


I once setup an old splendide combo washer to run off of battery. Bank was 12vdc (SLA), and I used 3 12-48vdc isolated boost converters in series to supply 140vdc direct to inverter inside washer. Stupid porter at camper repair killed washer with fork from forklift. Repair shop was sued, I won. You wont be able to do the same, but thunk outside the box. Your air conditioners can be reworked by a professional to increase efficiency (a lot!).


I added a second air conditioning compressor to my engine. Allowed me to build my version of air conditioner. My coach was wired for three, bit only had 2. I moved the rear all the way to the front, and installed my frankenstein ac in rear opening. When engine ran, it blew cold air into ductwork and went to all areas. If you approach this method, be sure to reinforce ductwork. Dont blow yours out like I did with too much airflow / pressure.


To augment your hot water, consider using solar collector on roof. Mine were 8foot lengths of 3" abs pipe. My 3 collectors each held about 7 gallons, for a water weight of 165 pounds. They did circulate to Atwood XT water heater that had engine coolant loop. Yes, i did have to use a 12v taco pump.



I made solar covers for my slideouts. Basically flex panels glued to fabric and laid on top of slideout awning. Anchored in place using bungee. Dont forget to remove when retracting slides.


There is an engine based inverter sysyem available from Vanner Systems and other companies. Engine alternator is basically a high voltage dv alternator that feeds an inverter that then supplies ac and dc power where needed. Almost bought one installed until I realized that spares are not available everywhere.


Hope this got you thinking.

Quote:

Originally Posted by cwk (Post 5434714)
Here are some parts of the plan:

Replace propane fridge with 110V residential unit.
Replace the propane water heater with a 110V electric unit.
Remove ALL propane systems.
Add 24V radiant floor heating.
Replace FLA batteries with LiFeP04 batteries in a 24VDC configuration.
Replace the separate MSW inverter, charger, and ATS with a Victron Inverter/Charger (possibly 24V/3000W?)
Remove original 100W solar panel on roof and add more modern panels.
Add all of the necessary wiring, controls, monitors, etc. as needed for the wiring. (Leaning toward Victron components.)
Rewire the 110V so the two (2) roof heatpump units can be powered by the inverter(s).


Here is one piece of the puzzle that has me stymied. If I was installing 12VDC system, I could charge the house FLA (or AGM) batteries with the main engine alternator while driving. I have read that with lithium batteries, since they can take a high amperage charge, it is very wise to install a DC-DC (buck converter?) unit to limit the amount of current so the alternator does not overheat and self-destruct.

Is there such a unit that can limit the current and also step up the alternator's 12VDC to 24VDC to charge the 24VDC battery bank? Is called this a "buck-boost converter"?

Also, is this recommended? Or, should I rely on solar, generator, and/or shore power only to charge the house batteries and forego connecting the alternator output to the house system?



ALSO:

Thanks to paul65k and astrocamper for their descriptions of their systems. Both have been very helpful. :bow::bow:


Florida Rang 09-20-2020 07:54 PM

I recently saw a Custom made Prevost that was Totally Electric. I mean stove , water , ac, heat, refrigerator , heated floors every system on this Coach was electric. You name it , itís electric. Just like a totally electric house, and No solar , Nu Lithium batteries. He had increased his fuel tank size and had a Diesel 25 KW Generator. He said is was simply easier to maintain only one power supply system. Said he had Boondocked for 10 days and still had plenty of fuel left. It was him and his wife. And sometimes 2 grandkids....( It was a 650hp automatic Volvo engine , and No he never said what it cost $$)

bobfrommaine 09-20-2020 09:16 PM

They do make 24V alternators. Most alternators can be rebuilt with 24V regulators, or if they have external regulators, just buy one. The alternator itself is capable of sourcing up to 48V.
Bob '14 Winnebago 37F Adventurer; Jeep toad.

Ponobill 09-20-2020 11:29 PM

As usual, a lot of people are telling you it can't be done, and they are the folks that never try anything challenging. I'; doing the same thing with a 1978 GMC motorhome. They are much smaller than most modern motorhomes, and I managed to put 1860watts on the roof. My battery is two modules from a Tesla Model S--11.2KWH. But enough about mine, let's talk about your choices.



YES in big letters, to the idea of disconnecting the house battery and electrical system from the motorhome. Two reasons--they are independent functions, and the most efficient voltages are not compatible. You should be looking at 48V for your house DC. That will let you decrease the size of all your major DC wiring. Sigeneer makes 48VDC. split phase 240V inverters which will give you both 120V and 240 AC. That means you can bin the rooftop AC and install multi head unit mini split AC. A fraction of the power demand and starting current, noiseless and very efficient.



I'd also consider a refrigerator like the Nova Kool--extremely efficient and simple. My simple interior uses induction cooking plates instead of a stove. You can cook inside or outside and the better ones can also function as slow cookers or do multiple temperature complex cooking.



I'd say step WAY back in your planning and take your time. Find out what is available and don't just look at the usual RV stuff, which tends to be very expensive on a per-watt basis. I'm well on the way to building exactly what you are planning and so far everything works MUCH better than i expected.



I posted some stuff about a year ago on this blog. It's kind of out of date, and some of the choices i made are limiting. But so far I'd say this is a much more usable RV than any I've experienced--I don't need to plug it into anything, just stick it in the sun. You'll need to dig around here, but there's some information you should find useful. I need to update all the work I've done. I almost wish I was starting over--I know a lot more know and could make this even better.



https://www.ponostyle.com/wiring-for-solar/

aircommuter 09-21-2020 08:41 AM

As a home builder, I think you may find that the amount of net energy in a tank of propane in more than you think.

glennwest 09-21-2020 10:17 AM

Quote:

Originally Posted by n0arp (Post 5448437)
There are several features that Victron offers that Magnum doesn't (ESS, DVCC, VRM, etc), that are compelling reasons for a lot of users to spend the extra money.

You and I discussed some of these in depth on one of the FB solar forums several months ago, so I know you're aware of them.

If the additional features don't justify the costs, or footprint in your case, you are free to buy whatever fits your budget and location.

Well, we don't know what ESS, DVCC, VRM is

n0arp 09-21-2020 10:42 AM

Quote:

Originally Posted by glennwest (Post 5449377)
Well, we don't know what ESS, DVCC, VRM is


They're things that don't make this an apples to apples comparison, as you already know from previous conversations.

For those of you who don't know:

ESS is a technology that allows you to load share and prioritize certain energy sources over others, in a nutshell. You can use it to prioritize solar and say, the top 40% of your battery bank before using shore power to support your loads. This is especially useful if you are over wintering at a FHU site that has metered electricity, and want to use electric heat.

DVCC is an advanced battery management algorithm that integrates of all your charging devices - charge controllers, inverter/chargers, etc, and your BMV so that they work together rather than act as ad-hoc devices.

VRM is a portal that collects data from GX devices and provides real-time and historic reporting of collection, utilization, and all sorts of other metrics.

glennwest 09-21-2020 10:47 AM

Magnum does load sharing. Magnum will work on 30 amp and pull what else it needs from battery. All the bluetooth stuff a lot of us will never use.

n0arp 09-21-2020 10:50 AM

Quote:

Originally Posted by glennwest (Post 5449423)
Magnum does load sharing. Magnum will work on 30 amp and pull what else it needs from battery. All the bluetooth stuff a lot of us will never use.

ESS is not basic load sharing like Magnum Load Support. That is a different - Victron calls that capability PowerAssist.

PowerAssist is just a small part of what ESS does.

None of the three features I mentioned use Bluetooth.

For anyone interested, you can see some demos of VRM at https://acceptancevrm.victronenergy.com/

glennwest 09-21-2020 11:01 AM

And I see no value in all this. Once I get it working, I will not be monitoring it. Got others things to do, like have fun.

n0arp 09-21-2020 11:05 AM

Quote:

Originally Posted by glennwest (Post 5449448)
And I see no value in all this. Once I get it working, I will not be monitoring it. Got others things to do, like have fun.


To each their own. The metrics here are very useful for predicting and comparing utilization, troubleshooting, etc. You don't need to use them often but will run across times where you will wish you had them.

Again, if the features aren't important to you, buy something else. Like the Xantrex XW6848 or Magnum inverters you're always pitching - but never buying.

glennwest 09-21-2020 11:19 AM

Quote:

Originally Posted by n0arp (Post 5449454)
To each their own. The metrics here are very useful for predicting and comparing utilization, troubleshooting, etc. You don't need to use them often but will run across times where you will wish you had them.

Again, if the features aren't important to you, buy something else. Like the Xantrex XW6848 or Magnum inverters you're always pitching - but never buying. Until you have some real world experience with any of these, I don't see why I should place any value on what you see value in.

Seeing as your attack about me never buying I need to explain. Got all this started and virus lockdown hit. I have not worked since. So I had to put all this on hold. But I have have plenty of time to research. Victron makes some nice equipment but most people will never use in an rv. Simpler it is the best.

n0arp 09-21-2020 11:25 AM

Quote:

Originally Posted by glennwest (Post 5449468)
Seeing as your attack about me never buying I need to explain. Got all this started and virus lockdown hit. I have not worked since. So I had to put all this on hold. But I have have plenty of time to research. Victron makes some nice equipment but most people will never use in an rv. Simpler it is the best.

I was insinuating that you get on forums and claim to be an expert on all of these things when you have no practical first-hand experience with any of them, and are argumentative when people call you out on your false and/or incorrect claims.

I'm sorry that you are out of work - hopefully you find something soon.

paul65k 09-21-2020 12:03 PM

See comments in Bold below.

All of our equipment is VIctron including the Cerbo and GX Panel which allows us to monitor our system in total even when away from our coach :cool:
Quote:

Originally Posted by cwk (Post 5445834)

Battery Bank: 12VDC LiFeP04 batteries in a 24VDC configuration. Number of batteries will depend on results of electrical usage survey.

This is what we did, currently have 10.6 Kw, may go to 13.3Kw

HVAC: Taking a very serious look at a two-zone 18-24K BTU minisplit with a small Indoor unit in the bedroom and a larger Indoor unit in the center of the coach facing forward. That still leaves the bathroom (the floor plan is a side hallway with a completely closed bathroom; not a walk-through bath). The Outdoor unit would go in one of the basement bays; possibly the one where the current gas furnaces live. There are 120VAC mini-splits, but they have smaller BTU's and that would require two complete installations for the coach. The larger Outdoor units require 240VAC.

Finding locations for the Indoor Units is a bit of a challenge. Since I am removing/redesigning/replacing most of the cabinetry, etc. anyway, I can redesign as needed. The installation manuals for some of the Indoor Units are helpful. Online youtube installation videos seem to be helpful as well. (What did we ever do before the Internet? :whistling: )

I recommend you take a look at the LG dual zone system with the "Wall Art" units. We plan to use these and this will allow us to do so with no cabinet modifications. We'll use the 9K unit in the Bedroom and a 12K unit in the main living area.


240VAC: This is needed for the above mini-split. Victron apparently makes an inverter/charger model so that two of them can be connected to supply 240VAC.

This is how we have our system set-up. I wired the units into the main panel and powered all circuits, moved the circuits from the inverter subpanel into main panel and replaced it with a small 240V subpanel and ran wiring to future location of Outdoor mini-split unit in the basement



The existing generator will provide 120VAC to the two inverter/chargers.

Shore Power will provide 120VAC to the two inverter/chargers.

Yup....this is exactly how this works, either provides 140A (@24V) charging plus whatever our solar puts out

Victron apparently makes a unit that will convert 24VDC to 12VDC so I can power all of the 12VDC house items: water pump, lighting, etc.

We have (2) 24-12/70A orion converters that power the 12V bus and are able to handle all 12V loads including the leveling system that is rated at 125A

I am considering NOT connecting the main engine alternator output to the House system. In fact, I think I want to completely separate the Chassis and House systems at all times. The only time I may need to connect them is if the Chassis batteries die and I need to start the main engine. Others have said a temporary connection with Jumper Cables will do the trick until Emergency Repairs can be completed.

We added (2) 24-12/15A DC-DC smart chargers that run from our oversized 240A alternator and these are providing ~40A in real world application, this along with our 1600W of solar allows one rooftop AC unit to run while we are driving and most importantly still send approx 10-15A to the house batteries, with good sun


Solar will provide some high voltage power to one or more MPPT controllers to charge the batteries. Not sure where they are connected yet, but will learn that once I start the electrical schematics. :D

We have a 150/100 MPPT and since converting to 24V it rarely puts out more than 50 - 55A so the long term plan is to up the Solar to around 3K, which will be doable wen I remove the rooftop AC units

Please feel free to PM me if you want more info:thumb:





glennwest 09-21-2020 12:33 PM

Quote:

Originally Posted by paul65k (Post 5449520)
See comments in Bold below.

All of our equipment is VIctron including the Cerbo and GX Panel which allows us to monitor our system in total even when away from our coach :cool:

Don't see how one can use the wall mount units. Most rvs don't have a wall one can even hang a picture on. You must but most don't.

n0arp 09-21-2020 01:26 PM

2 Attachment(s)
Quote:

Originally Posted by glennwest (Post 5449556)
don't see how one can use the wall mount units. Most rvs don't have a wall one can even hang a picture on. You must but most don't.

Attachment 301779Attachment 301780

Every rig is different, but we had no problem finding locations for our two indoor units. At least with larger fivers, I wouldn't think it would be an issue. Class A rigs like paul65k's might be more difficult. Fujitsu, I believe, makes some floor mounted units that look interesting for such applications.

Edit - like https://www.fujitsugeneral.com/us/pr...ies/index.html

paul65k 09-21-2020 01:28 PM

Quote:

Originally Posted by glennwest (Post 5449556)
Don't see how one can use the wall mount units. Most rvs don't have a wall one can even hang a picture on. You must but most don't.

2 ways,
  1. In my case I had wall space in the hallway next to the equipment closet
  2. I plan to move it to the location of the original Xantrex control panel which is no longer in use

paul65k 09-21-2020 01:29 PM

1 Attachment(s)
Quote:

Originally Posted by glennwest (Post 5449556)
Don't see how one can use the wall mount units. Most rvs don't have a wall one can even hang a picture on. You must but most don't.

We'll be using these

glennwest 09-21-2020 02:21 PM

I have mini splits. But a 24X24 would not fit anywhere in mine. The standard wall mount did. Bedroom had to put a cassette.

paul65k 09-21-2020 02:43 PM

Quote:

Originally Posted by glennwest (Post 5449692)
I have mini splits. But a 24X24 would not fit anywhere in mine. The standard wall mount did. Bedroom had to put a cassette.

We actually have a wall that is next to the refrigerator and room over/on the headboard that we will be modifying.:thumb:

cwk 10-22-2020 07:49 PM

Based on some of the suggestions received so far... :bow::bow::bow:


I have been researching mini-splits. A family member just installed a 24K BTU unit in his 1100 sqft shop building. I had a chance to visit last weekend and listen to it in person. There is not much to hear! :cool:

All that I can say is Wow! It is quiet.

This past year I replaced the front roof A/C in our coach with a new 15K heatpump. It is quieter than the original roof A/C. But is still loud. I had planned on adding ductwork to diffuse the sound of the rushing air, but DW and I can still hear the compressor on the roof.

I listened to that 24K mini-split. It was cool outside, so we turned the heat on and played with the fan speeds inside. Wow. This thing is quiet: both inside and outside.

So, based on what I have learned so far, a mini-split system is probably in our future.


But, I still have a few questions.

Last night, while researching vendors online for a two-zone system (up-front and bedroom), I found a vendor that had a special on a "2-zone system" which was actually a sale for buying two single zone systems.

One of the benefits is that the units are 120V, not 240V like the larger 2-zone systems. Our coach does not currently have 240V. The Onan generator is 120V. We could use two Victron Inverters to create 240V. But that would mean a lot of rewiring, etc. Another benefit supposedly is that the two separate units should be more energy efficient than one larger system.

Also, last night, I read a post here on iRV2 with a comment that two separate systems would be more efficient as well. (Thanks to hclarkx.) Talk about timing. Both discoveries made within hours of each other? Hmm... :whistling:

The trick is where to place the outside units on a Class A. I am thinking about one unit where the current propane tank is. And, the other unit where the current gas furnaces are located. Measurements need to be taken to be sure, but that is the direction at this point. (Thanks again to the iRV2 member that pointed me in the direction of the Bus Conversion videos.)


QUESTION: How much difference will a higher SEER rating mean to me?

The goal is to be able to run the mini-splits as much as possible on SOLAR and LifeP04 batteries.


One vendor has a 9K BTU unit at 17 SEER, another at 22.8 SEER, another at 23 SEER, another at 25 SEER, and even one at 30.5 SEER.

I even found a 6K BTU unit at 33 SEER. (How many BTU's does a coach bedroom need anyway? (No slides, bedroom accessed by a side-hallway instead of an open bathroom plan)


And, while I am asking, how many BTU's does the front end of the coach need? No slides, 38' DP, adding 1/2" foam insulation to the walls, single-pane windows.

Thanks to everyone who has commented. Our remodeling plan is now much better for it. :bow:

paul65k 10-24-2020 11:21 AM

1 Attachment(s)
I've already wired my dual Victron 24/3000s for 220 and we have a dedicated sub panel and wiring for the future outdoor unit which will be in the former battery compartment (Lithiums were moved inside) on our 36'DP.

I plan to install the LG system which has the unique "Picture frame: heads that I'll be able to mount without needing to re-work or lose cabinet space. The plan is to use a 9K unit in the bedroom and a 12K unit in the front of the coach. From everything I've read the Mini-Split puts out much more cooling from lower sized units than comparable rooftop units.

The specs for both units running is actually a little lower than a single rooftop unit which I can currently run with full sun and our 1600W of solar.

I just wouldn't be able to make room for 2 outdoor units and setting up the inverters for split phase was really not a big wiring deal

It will be interesting to see how :thumb:both out installations come out:thumb:

hclarkx 10-24-2020 02:23 PM

Some thoughts .....
 
My son is in the process of installing a 6K and a 9K on his older Class A. I'm planning a 9K on my 30' 5er. Final decisions are yet to be made, but we are looking at the cost of additional solar and battery versus higher efficiency mini splits. He has four 6K Mitsubishi SEER 33 units on his small LA area home. I have two multi-splits and two mini splits on my northern CA home.

His home 6K Mitsubishi units draw something like 315 Watts at full output which can exceed 6K if it's not too hot out. The cost is about double what a 120V Mr. Cool or Pioneer costs and the outdoor unit is heavier IIRC. As for cost, the SEER 33 Mitsubishi is about twice what a Mr. Cool or Pioneer (SEER 22) costs, roughly $1600 vs $800, enough to buy 800W of panels per mini split. Or 1600W total. One might need more battery though that depends largely where and when one camps (whether overnight A/C is needed). Since these units don't need 800W in the first place, going with SEER 22 and more solar seems like the answer. The Mitsubishi does have a turn-down ratio of 4:1 but some of the less coslty units do as well. Others are 3 to 1 but that may be enough since our RVs are not well insulated. They all seem to be quiet. I don't think failure from potholes is likely, but the less costly units are less costly to replace if that happens. And the 120V units don't need a 120-240 transformer or a 240V inverter.

Son has room for an outdoor unit next to his diesel in the back. Other one will probably go in the up-front generator compartment since the generator will be replaced with a 35# 1kW inverter generator for the rare occasion of days of too many days inclement weather.

When I get the 9K mini split on my 5er I'll use solar for winter heat to the extent the sun is good, with propane as backup. So far I have no power connector and my electrical panel is wired only to my inverter. Fridge is a Nova Kool RFU9000. 1000W of solar is ample. I'll add 600W for the 9K mini split. My 300 AH battery is sufficient for the times and places we camp (don't need all-night cooling from the A/C).

As for the BTU/Hr for the front end of the DP, my son is planning 9K for his 34' DP. That is based more on gut feeling and experience with mini splits in room sizes and such than a technical analysis. One could attempt a "manual J" heat gain analysis but it would be rough. The furniture along the walls and cabinets and such provide considerable insulation. Generally 9K is enough for up around 300 square feet in a home and should do fine with an 8x12 RV front end (100 square feet). A curtain mid cabin would somewhat confine the cooling if need be.

Do you have a spreadsheet program? I can send you a spreadsheet that will help in planning. It even models two different A/C units with different daily and seasonal usage patterns (cooling and heating). It helps calculate your current and future load if needed, takes into account where and when you camp, representative weather patterns (think multiple cloudy days), etc. etc. It will even help you size the auxiliary generator for the rare inclement weather need. And tell you how often you will use it (more battery and more solar equals less frequent use). PM me if you'd like to have the spreadsheet.

Have you looked at the Secor/Danfoss 12V fridges? Some are pretty fancy. Potentially save a lot of energy over a residential unit. My 9.1 cu ft (probably smaller than you would want .. there may be larger ones available) uses around 40 AH per day. I added considerable insulation to greatly reduce the energy use. It needs only about 50 AH of battery and 200 W of solar.

Give me a call if you wish ....... 916.426.6802.

hclarkx 10-24-2020 03:10 PM

Quote:

Originally Posted by cwk (Post 5445834)
OP here.


Floor Heat: Looking at a 120VAC mat system to be installed over the existing 3/4" marine plywood floor. Then, probably engineered wood, or some type of vinyl flooring (no carpet). DW is still in the interior design phase. I priced a 24V mat system from one supplier. The price was about 5K, just for the parts. I would be providing the labor, but I still thought this was high. 120VAC pricing appears to be much more reasonable.

Have you looked closer at this? I'm thinking that resistance heat uses 1 kW per kW of heat. A heatpump (COP=4) uses 1 kW to produce up around 4 kW of heat. So about 1/4 of the solar to produce the same heat.

jcussen 10-24-2020 03:19 PM

Actually resistance heat is about 5100 btus for about 15 amps at 120 volts. A rooftop heat pump will produce over 12000 btu's at the same amperage and voltage. I imagine a mini-split unit would be even more efficient.

hclarkx 10-24-2020 03:42 PM

Quote:

Originally Posted by jcussen (Post 5493389)
Actually resistance heat is about 5100 btus for about 15 amps at 120 volts. A rooftop heat pump will produce over 12000 btu's at the same amperage and voltage. I imagine a mini-split unit would be even more efficient.

I haven't looked at rooftop heatpumps lately, but early on they didn't seem worthwhile. And in my case I needed the roof space for solar. I've been without A/C for six years ... but being retired, I can avoid hot places.

15 x 120 is about 1800 Watts (ignoring power factor). Even a low-end 9K mini split needs well less than half of that (around 700W I think). A pair of 6K Mitsubishi SEER 33 at 315 Watts would provide 12,000 BTU/Hr for 630 Watts.

It's surprising that mini split heat pumps haven't gained more favor among the RV manufacturers. Or in new homes for that matter. My daughter bought an expensive new home recently and heat pumps were not an option. I converted my 47 year-old house to heat pumps and am heating and cooling for considerably less than the 10 year old SEER 14 package unit needed for just cooling (we are not in snow country, but do see low 20's in January).

jcussen 10-24-2020 04:03 PM

Quote:

Originally Posted by hclarkx (Post 5493406)
I haven't looked at rooftop heatpumps lately, but early on they didn't seem worthwhile. And in my case I needed the roof space for solar. I've been without A/C for six years ... but being retired, I can avoid hot places.

15 x 120 is about 1800 Watts (ignoring power factor). Even a low-end 9K mini split needs well less than half of that (around 700W I think). A pair of 6K Mitsubishi SEER 33 at 315 Watts would provide 12,000 BTU/Hr for 630 Watts.

It's surprising that mini split heat pumps haven't gained more favor among the RV manufacturers. Or in new homes for that matter. My daughter bought an expensive new home recently and heat pumps were not an option. I converted my 47 year-old house to heat pumps and am heating and cooling for considerably less than the 10 year old SEER 14 package unit needed for just cooling (we are not in snow country, but do see low 20's in January).

Actually they are getting more efficient in heat pump mode, this one puts out 15000 btu's.
https://www.recpro.com/rv-air-condit...P6cCBoCkCwQAvD

But agree none approaches the efficiency of a mini-split. Problem with motorhomes, no really good place to put the compressor/condenser unit without using up a lot of bay space.

hclarkx 10-26-2020 12:21 PM

Quote:

Originally Posted by Rocketman3 (Post 5437319)
For the 12 v side, I was think of putting one marine battery lead acid battery. Then using a 48v or 24v to 12 volt converter to run all the 12 v stuff. If my 12 v draw was more than the converter could handle - it would pull down the 12v battery a little. This way I keep the emergency battery assist to start the chassis engine.

I think this is a good idea. The power system in my Volt does exactly this ... albeit from a much higher voltage main battery. Some heavy 12V loads like tank heaters would probably dip into the battery. And you'd have the 12V battery to manage 12V loads for a few days should the DC-DC converter conk out.

Krbjmpr 10-27-2020 12:14 AM

Quote:

Originally Posted by hclarkx (Post 5496244)
I think this is a good idea. The power system in my Volt does exactly this ... albeit from a much higher voltage main battery. Some heavy 12V loads like tank heaters would probably dip into the battery. And you'd have the 12V battery to manage 12V loads for a few days should the DC-DC converter conk out.




As stated, and I know it wasn't your idea but Rocketman, I think this is a terrible idea.


We all consider our basic battery system to be 12v, but when everything is working as it should, voltage is actually 13.8-ish on converter and 14.2-ish off the alternator.


The DC-DC XXvolt to 12v converter (Buck Regulator) is going to put out 12volts and a few tenths. This won't be enough to keep the aux battery charged. 12.6v (or 12.8, I forget) is full charge voltage on a battery at rest. 12v on a battery at rest is dead (20% I think). You need a converter that is capable of at least 13.2 (lead acid float voltage) and at least enough current capacity to run loads & charge battery. Personally, I would start at 50Amps. This is going to require a fairly exotic DC-DC Converter. They do exist, but mostly for electric golf cart market whose owners are running electric beer coolers, lighting, power steering (not kidding), and of course a heckuva sound system to listen to on way to next hole.

Krbjmpr 10-27-2020 12:32 AM

Not as exotic as I thought...


48 to 13.8 @ 30Amps $35.60

https://www.amazon.com/Converter-Reg...8vdc+Converter


24 to 13.8 @ 40Amps $31.99

https://www.amazon.com/Automatic-Con...8vdc+Converter


Wish these were available a few years ago. I Had to use a chain of 6v (6.5v) *isolated* converters to individually charge a battery bank consisting of (8) GC2 in series. Even then, I couldn't equalize without use of a generator.


Using the above converters, I would definitely be implementing this If I had a 24/36/48v battery bank. Lack of converters is the *only* reason why I am not using my Ancient but very reliable 5Kw Heart Interface sinewave inverter and a 36v battery bank. That will change as soon as I get battery box welded up, cables made, etc. when it warms up next Spring.

richard5933 10-27-2020 07:57 AM

Quote:

Originally Posted by Krbjmpr (Post 5497116)
Not as exotic as I thought...

...

24 to 13.8 @ 40Amps $31.99

https://www.amazon.com/Automatic-Con...8vdc+Converter

....


I used four of these to update the four circuits feeding my 12v headlights from a 24v chassis battery system. From the factory they used a resistor bank to drop the voltage, which resulted in the headlights having varying outputs as the engine speed changed.

These converters put out a constant 13.8v which is the ideal voltage for most 12v appliances used in the auto industry. Since most RV house batteries charge at this (or nearly this) voltage, it is a good voltage to use for running RV house systems.

I've driven many miles using these to power the headlights, which are on all the time, and there have been no problems. I could have used converters with lower capacity, but went with these to help keep the heat buildup down. I mounted them on a piece of 1/8" aluminum sheet which has an air gap under it to provide a way for heat to escape.

Ponobill 10-27-2020 09:24 AM

Some good solutions here, but i took a different course. In my motor home conversion all the house loads are supported with a 24V bus with local 12V converters to suit the load. Small converters are cheap and reliable, but mostly cheap. The only 12V battery I have is the engine battery and a lithium booster that floats on the AC system. The booster is just a portable unit that is removable if I need to give someone else a boost. I can engage it from the driver's seat with a toggle switch that closes a relay.



using 24V as the bus means the bus current is half, so the wiring doesn't need to be heavy. In retrospect I wished I'd done 48V, though the converters would be harder to come by. I have some small ones with adjustable output that are good to 3A output. I've been running them in a test rig for three months driving a full 13.5V 40W load 24/7. They barely get warm. I have larger converters up to 150W. I bought them mostly on Aliexpress, since they all come from China anyway.

Krbjmpr 10-27-2020 09:29 AM

Quote:

Originally Posted by richard5933 (Post 5497288)
I used four of these to update the four circuits feeding my 12v headlights from a 24v chassis battery system. From the factory they used a resistor bank to drop the voltage, which resulted in the headlights having varying outputs as the engine speed changed.

These converters put out a constant 13.8v which is the ideal voltage for most 12v appliances used in the auto industry. Since most RV house batteries charge at this (or nearly this) voltage, it is a good voltage to use for running RV house systems.

I've driven many miles using these to power the headlights, which are on all the time, and there have been no problems. I could have used converters with lower capacity, but went with these to help keep the heat buildup down. I mounted them on a piece of 1/8" aluminum sheet which has an air gap under it to provide a way for heat to escape.


Do you have the ability to measure current in and current out? I use several 12 > 6 and then 6 > 12 converters to feed my electronics (router, BR burner, drives, anything with 12v wallwart). This allows me to switch to 6vdc LIFE for extended outrages. I also use 12 > 24 for my winega rd WC3000 booster. I am seeing about an 80%, rated draw, to 90%, light load. I don't have anything that could pad a converter with a 55/60w continuous draw.

richard5933 10-27-2020 09:53 AM

Quote:

Originally Posted by Krbjmpr (Post 5497402)
Do you have the ability to measure current in and current out? I use several 12 > 6 and then 6 > 12 converters to feed my electronics (router, BR burner, drives, anything with 12v wallwart). This allows me to switch to 6vdc LIFE for extended outrages. I also use 12 > 24 for my winega rd WC3000 booster. I am seeing about an 80%, rated draw, to 90%, light load. I don't have anything that could pad a converter with a 55/60w continuous draw.

Not sure I fully understand the question.

The headlights are a known wattage, and I sized the converts to be nearly twice the needed size to allow them to run cool. Doesn't really consume any extra power having the extra capacity as the headlights only draw what they draw.

The OEM wiring was actually done well, with a totally separate circuit for each of the four lamps. One circuit can go totally out without affecting the others.

Regarding DC appliances in the coach - if there are any capable of running on 12vdc, then I've already got them wired to do so directly. I have eliminated all of the wall warts possible, as they do nothing to add to efficiency.


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