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paul65k 01-25-2021 10:14 AM

Generator charging upgrade???
 
So the question is.............. Would you spend $~750 if you could charge your batteries twice as fast with your generator?

Note: While I have a 24V system I'll use 12V numbers as most have a better point of reference on 12V systems

My current set-up with dual Victron Inverter/chargers will charge my Lithium battery bank at up to 280A (2X140A for each inverter/charger) if I am feeding the inverters with split-phase power (120/240V), for instance, 50A shore power.

Each charging leg uses about 20A to run each charger but if I use the on-board 7500W generator it is only capable of 120V output even though it can deliver as much as 62A it is limited to only one inverter charging as it is not delivering this power in "Split-Phase".

The solution seems to be to use an autotransformer to change the generator output to "Split-Phase (120/240) which will allow both chargers to be in service while using the generator..... a full charge as currently configured can take up to 3 hours, with the autotransformer this is down to 1.5 hours!

My data shows that our cost of generator power is ~$2 per hour all in so the payback is 400 hours and might not make financial sense but the value of not hearing that generator run any longer than necessary is to me...................... Priceless

What do you all think???

Old Scout 01-25-2021 10:50 AM

Not sure I follow--what does phased vs non-phased 120v legs [2] on genset have to do with running separate chargers--you don't need split-phase to run two A/Cs on genset?..I think most of us only have one charger and no Li bats [smile]. So for me, since we don't do a lot of dry camping--its hard to have an opinion....but I do admire your solar/bat set-up.....its top shelf!
Ps--I was pretty happy with my solar upgrade to 600 watts before going to Q-site this year....ran my genset 1 or 2 hours in the morning and maybe 1 hour at night....had between 83-86% SOC [as read on my new Victron battery monitor]on my six 12v L/A bats [some TV, a bit of propane furnace heat and a resid-fridge].....lots of sun shine this year so 600 watts fully recovered bats by early afternoon and kept them at 100% for rest of the day.

paul65k 01-25-2021 12:08 PM

Quote:

Originally Posted by Old Scout (Post 5609540)
Not sure I follow--what does phased vs non-phased 120v legs [2] on genset have to do with running separate chargers--you don't need split-phase to run two A/Cs on genset?..I think most of us only have one charger and no Li bats [smile]. So for me, since we don't do a lot of dry camping--its hard to have an opinion....but I do admire your solar/bat set-up.....its top shelf!
Ps--I was pretty happy with my solar upgrade to 600 watts before going to Q-site this year....ran my genset 1 or 2 hours in the morning and maybe 1 hour at night....had between 83-86% SOC [as read on my new Victron battery monitor]on my six 12v L/A bats [some TV, a bit of propane furnace heat and a resid-fridge].....lots of sunshine this year so 600 watts fully recovered bats by early afternoon and kept them at 100% for rest of the day.

Very cool....happy that is working out for you!!

In our case, the 2 inverter/chargers that we now have installed are set-up in split-phase (120/240) which requires the power in to be 180* out of phase just like a 50A shore power cord will do. this is our case as we plan to upgrade the rooftop AC to a mini-split with 2 zones, which require a 120/240 connection just like at home and we can now do this.

When the generator was installed at the factory it was set-up to feed both sides of the 50A panel but there was no need for split-phase or "220" as none of the circuits needed the split-phase wiring. In our case, we still get good charging from the generator but it could actually be DOUBLE for $~750.....This is the dilemma:angel:

Brianna 02-04-2021 03:13 AM

Paul,
Sounds like a solution looking for a problem, in my opinion.
Imagine how much wine/beer you could buy for $750.

��

paul65k 02-04-2021 03:36 PM

Quote:

Originally Posted by Brianna (Post 5622440)
Paul,
Sounds like a solution looking for a problem, in my opinion.
Imagine how much wine/beer you could buy for $750.

��

I think of it a little more like the guy who just spent $15K on a new more powerful engine for his hot rod and his transmission won't let him take it out of 3rd gear ;)........for $700 more he can now use 4th, 5th, and 6th gear and get the full potential out of that new motor...... Right?? :cool:

Freqz 02-04-2021 03:44 PM

Sure. Itís only money, right? Not listening to the genset drone on for an extra hour/day has to be worth something, right?

Added benefit is running your 240V loads off 30, 20, or 15A shore power with less stress on the batteries.

paul65k 02-04-2021 08:20 PM

Quote:

Originally Posted by Freqz (Post 5623269)
Sure. It’s only money, right? Not listening to the genset drone on for an extra hour/day has to be worth something, right?

Added benefit is running your 240V loads off 30, 20, or 15A shore power with less stress on the batteries.

Actually The system will already run 240V loads from the existing inverters on batteries alone or with any of the 30/20/15A inputs including the generator input as the dual inverters are set-up as split-phase......the Autotransformer will allow the generator to drive both chargers vs just one when charging the batteries from the generator:D

Freqz 02-04-2021 09:02 PM

Quote:

Originally Posted by paul65k (Post 5623635)
Actually The system will already run 240V loads from the existing inverters on batteries alone or with any of the 30/20/15A inputs including the generator input as the dual inverters are set-up as split-phase......the Autotransformer will allow the generator to drive both chargers vs just one when charging the batteries from the generator:D


Yes, but the second inverter is 100% battery powered right now in that scenario, no? The auto transformer would allow you to run both on AC with zero DC draw which is *small* benefitó saves losses on AC-DC-AC conversion (negligible, probably) and micro cycles on the batteries. :). Batteries are expensive enough that treating them with baby gloves is a plus, IMO.

But really, dumping 2X the current into the batteries from the gen is worth $700 or so in my world.

paul65k 02-04-2021 09:10 PM

Quote:

Originally Posted by Freqz (Post 5623673)
Yes, but the second inverter is 100% battery powered right now in that scenario, no? The auto transformer would allow you to run both on AC with zero DC draw which is *small* benefit— saves losses on AC-DC-AC conversion (negligible, probably) and micro cycles on the batteries. :). Batteries are expensive enough that treating them with baby gloves is a plus, IMO.

But really, dumping 2X the current into the batteries from the gen is worth $700 or so in my world.

I agree, you're absolutely correct!......I'm still trying to figure out how to wire it in so that it will convert both the generator and 120V shore power without needing 2 of them:confused:

Freqz 02-05-2021 06:33 AM

Generator charging upgrade???
 
1 Attachment(s)
Quote:

Originally Posted by paul65k (Post 5623678)
I agree, you're absolutely correct!......I'm still trying to figure out how to wire it in so that it will convert both the generator and 120V shore power without needing 2 of them:confused:


Transfer switch...

Iíve been (very roughly) sorting this out for my FW build.

Attachment 317126

Brianna 02-05-2021 08:08 AM

I hope, some day to get a tour of the paul65k coach.
Everything written about it is so beyond, beyond, amazing.

paul65k 02-05-2021 10:07 AM

Quote:

Originally Posted by Freqz (Post 5623935)
Transfer switch...

Iíve been (very roughly) sorting this out for my FW build.

Attachment 317126

Thank you I'm still trying to figure out the way to wire after the transfer switch to the inverter(s).....dual Multiplus 3000s in my case.

Why would you need the AT on the output side of the Quattro......doesn't it already have 240V output capability?

If not you could use dual multiplus 3000s (about the same price as a single Quattro) and set them up for split-phase output, which would actually give you a bit more overall wattage???:confused:

paul65k 02-05-2021 10:08 AM

Quote:

Originally Posted by Brianna (Post 5624053)
I hope, some day to get a tour of the paul65k coach.
Everything written about it is so beyond, beyond, amazing.

Thanks but, she's just an "Old Beater"....but we love her:cool:

Freqz 02-05-2021 11:31 AM

Quote:

Originally Posted by paul65k (Post 5624255)
Thank you I'm still trying to figure out the way to wire after the transfer switch to the inverter(s).....dual Multiplus 3000s in my case.

Why would you need the AT on the output side of the Quattro......doesn't it already have 240V output capability?

If not you could use dual multiplus 3000s (about the same price as a single Quattro) and set them up for split-phase output, which would actually give you a bit more overall wattage???:confused:


It my case, it would be a 240V inverter so you need the auto transformer to provide split phase 120V. (I donít necessarily need split phase but I do need a neutral)

Iím building this around a 8k Quattro to support a mini split and induction cooktopó 6kVA seems a little light for my use. Your way gets more charging current and cost a bit less. Several ways to skin this particular cat!

paul65k 02-05-2021 12:12 PM

Quote:

Originally Posted by Freqz (Post 5624365)
It my case, it would be a 240V inverter so you need the auto transformer to provide split phase 120V. (I donít necessarily need split phase but I do need a neutral)

Iím building this around a 8k Quattro to support a mini split and induction cooktopó 6kVA seems a little light for my use. Your way gets more charging current and cost a bit less. Several ways to skin this particular cat!

Thanks!

I have a MS planned as well....as a matter of fact I already have the 240V subpanel installed and circuit run to the outdoor unit proposed location..... just trying to figure out the interior distribution plan, front and rear!

I can already run both rooftop units off the grid but calculating that the mini-split will use 40 - 70% less amps, depending on how we end up!:thumb:

Freqz 02-05-2021 12:46 PM

Quote:

Originally Posted by paul65k (Post 5624400)
Thanks!

I have a MS planned as well....as a matter of fact I already have the 240V subpanel installed and circuit run to the outdoor unit proposed location..... just trying to figure out the interior distribution plan, front and rear!

I can already run both rooftop units off the grid but calculating that the mini-split will use 40 - 70% less amps, depending on how we end up!:thumb:


Yeah, Victron shows ~2200W for my 15kBTU which is about what a 24kBTU mini split should take. Sheesh.

Iím still in the spitballing phase...this was much, much less complicated (and much cheaper!) for my 30A trailer [emoji849]. But itís also half the fun, I guess!

v8dave 02-10-2021 12:11 PM

Get a manual/diagram for your installed generator and investigate the capabilities of the generator itself. I'll bet it already has split 240 Volt dual circuit capability but has been configured to only supply a single circuit at 120 Volts.


If it seems capable, check with a full line service center (i.e. Freight Liner service center or equivalent that has electricians on staff) to see if they know how to do this.


Best Regards,

paul65k 02-10-2021 04:47 PM

1 Attachment(s)
Quote:

Originally Posted by v8dave (Post 5630764)
Get a manual/diagram for your installed generator and investigate the capabilities of the generator itself. I'll bet it already has split 240 Volt dual circuit capability but has been configured to only supply a single circuit at 120 Volts.


If it seems capable, check with a full line service center (i.e. Freight Liner service center or equivalent that has electricians on staff) to see if they know how to do this.


Best Regards,

So the QD 7500 is only capable of single-phase as the windings apparently can not support split-phase output. The windings are not capable of developing split-phase hence the need for the autotransformer:banghead:

In addition to this spec sheet, it was confirmed to me by Onan.

paul65k 05-24-2021 10:58 PM

Thought I would update this thread...........

I have the Autotransformer in my possession and plan to do the install next week. It looks pretty straightforward; I will intercept the input from the generator prior to reaching the transfer switch. The way it will be wired, the (2)v120V lines from the generator (sams phase) will feed into the Autotransformer on L1 which will then provide (2) lines out (L1, L2) which will now be 180* out of phase just like the 50A shore power input.....only difference will be that each line will only have 3600W (30A) each vs. the 6000W (50A) with a shore power connection.

Why is this important:confused:

Because right now when I run the generator L1 (1/2 the panel) is fed via pass-through and L2 (other 1/2) is fed by the 2nd inverter from the batteries while the 1st inverter is charging the batteries.......this of course is not the case with a 50A shore power connection because both L1 and L2 are 180* out of phase and each line passes straight through as well as BOTH are charging the batteries with a total output of 280A (@12V) which gets the batteries charged twice as fast ;)

I will have to do a little power management if I need to run the generator AND run both AC units at the same time which can cause the breaker at the genny to trip, but in our system, we can set the available amps to 30 or any number actually, and the Inverter/chargers will manage the loads based on that without putting excess draw on the genny :)

Is that as clear as mud:laugh:

paul65k 08-27-2021 09:37 AM

1 Attachment(s)
So auto transformer is in place and did in fact allow both battery chargers to work as well as allowing both legs of the electrical system to now work when generator is running.

In the photo please note that the charging is now at 129A and this is @24V so the equivalent of almost 260A @12V. Getting ready to add 2 more batteries so going from 840 Ah to 1050Ah of storage, this makes the faster charging even more critical for the times when our 1600W of solar may not be able to keep up[emoji41]

A very worthwhile $600 investment[emoji6]Attachment 341145


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