battery charging and boondocking

[droflex]

I have a 91 Cobra 28' class C.

It has a built in 5k onan generator which will run everything fine but only when it is running and it is very noisy and vibrates the rv. I have no battery bank (yet).

I have a storage area that can hold 8 Trojan t-105 (225) amp batteries. 1800 amps total minus 50% discharge plus 80% max charge equals 770 amps of usable power...right? That really sucks having 1800 cut down to 770. I've read that in "real life" you only get about 80% charge.

But there's more:

I also have a Honda ES6500 generator sitting in my garage which has very little use on it. It has 220 and 110 outputs, 5 gallon gas tank (if I recall) and is smart enough to vary the RPM's when it needs to according to the draw on it. It is WAY quieter that the onan as well. I could probably make it nearly silent if I put a different muffler on it too.

I only have the Honda generator for the (real) house for back up power and have only used in twice.

What I was think is this: What if I put that Honda generator on the back of the RV on one of those receiver hitch platforms with a couple 10 gallon gas tanks and use that to charge the 8 t-105's when they get low?

If so, what kind of battery charger would I use? And how long would it take to recharge that bank of batteries? I dont want to spend all day charging them back up to 80% or so.

I cant use solar 'cause I like to park under trees mostly.

Also, when I'm on vacation I dont like to be that close to people 'cause that's what vacation is for me so I'm not worried about upsetting the "neighbors" with the generator.

The onboard onan 5k genset would only be used as a backup.

Questions? Please ask away!

Thanks

[John Hilley]

Actually you would have only 900 amps at 12 volts, with 450 amp/hr useable. With a series connection of two or more batteries you get the sum of the voltage of the connected batteries, but the current capacity of the smallest one. So in a series connection of two like batteries you get twice the voltage, but the current capacity of one of the batteries. In a parallel connection of two like batteries, you get the voltage of one battery, but twice the current capacity of one battery.

[droflex]

Quote:

Originally Posted by John Hilley Actually you would have only 900 amps at 12 volts, with 450 amp/hr useable. With a series connection of two or more batteries you get the sum of the voltage of the connected batteries, but the current capacity of the smallest one. So in a series connection of two like batteries you get twice the voltage, but the current capacity of one of the batteries. In a parallel connection of two like batteries, you get the voltage of one battery, but twice the current capacity of one battery.

So your saying that things just got worse?

Does wiring it like this help?

Batteries - Series and Parallel Connections - AltE


Thanks

[mr300ce]

You probably would need to beef up the hitch receiver, as the weight of that genset 'bouncing' while driving will likely cause it to break.

I have a friend that beefed up his to carry his Harley.

[droflex]

Quote:

Originally Posted by mr300ce You probably would need to beef up the hitch receiver, as the weight of that genset 'bouncing' while driving will likely cause it to break. I have a friend that beefed up his to carry his Harley.

Oh you bet ya! I'll grab that stick welder and fire away. I even thought of putting a spring axle under it to absorb the bumps. Like a trailer. I would have the wheels/tires turn like the wheels on the front of a shopping cart so that backing up and going around corners would not cause undue stress to the system. Haven't got that far yet.

Correction, I do have one I built but it was for a snowmobile application and sold it to a friend. I'll post pic's if I get a chance. I came up with a possibly better design but haven't messed with it for a few months.

Still need solution to battery/charging situation first.

[John Hilley]

Quote:

Originally Posted by droflex So your saying that things just got worse? Does wiring it like this help? Batteries - Series and Parallel Connections - AltE Thanks

No, things would be pretty good with 8 batteries, 4 would probably be sufficient. The link explains series, parallel and series/parallel connections nicely.

[Shadowcatche]

The built in Onan would be where I put my attention, vibration mounts and a decent muffler and sound deadening. The use of a good converter/battery charger in conjunction with said generator to bring batteries up to full charge and the addition of solar panels to extend the don't have to run the generator time. Last but not least conservation efforts i.e. LED lights.

[jlyon69]

Quote:

Originally Posted by droflex I have a 91 Cobra 28' class C. If so, what kind of battery charger would I use? And how long would it take to recharge that bank of batteries? I dont want to spend all day charging them back up to 80% or so. Thanks

I would highly recommend a Intelli-Power PD9260C 60A Electronic RV Converter/Charger. I chose Progressive Dynamics over IOTA Engineering mainly because the PD has a remote control unit PD92201 Remote Pendant. This allows you not only to monitor in which mode the charger is in, it also allows you to manually change it, if you want to, all from inside the coach. PDs also have an Equalization Mode which eliminates sulfation during long storage periods.

Both PD and IOTA make good chargers. Both are automatic and have 3 charging phases. If memory servers, the PD has a higher voltage for boosting or quick charge. 14.4 vs 14.3 on the IOTA. Here is the PD chart for battery charging ...Charge Wizard.

Since you have a Class C, I assume your present charger is incorporated into an AC/DC Distribution panel. Although I had a Class C for a few years, I didn't know much about the electrical system. So you will either have to disconnect your present charger and find a location for the new one or, upgrade the whole panel. Here is PDs AC/DC panels The Intelli-Power 4500 Series AC/DC Distribution Panel and Intelli-Power Converter with Charge Wizard is the Ultimate All-In-One System. I'm sure IOTA has these two.

Overall your plan sounds very doable. I would also recommend beefing up the hitch! However, before I would discount that Onan, I would look into all of it's supports for anything lose or cracked. I would also investigate any original vibration reducing parts ie; rubber feet, etc. You may very well be able to reduce vibration more than you think. You're going to have to contend with that on your new plan also. You could also investigate an optional muffler/exhaust systems. I have seen them with a small exhaust pipe which exhaust above the roof, I would have to assume that reduces the noise quite a bit.

[wa8yxm]

One more concern in a class C (And a Gasser A) is cargo carrying capacity. What are 4 pair of six volt golf car batteries going to do to your total vehicle weight, That's a lot of lead. That said, if you got the capacity. GO 4 IT.

NOTE: just 2 pair can keep a 2KW inverter happy all night running TV and Sat receiver.. (NOT air conditioner) and may even have enough left in the AM for a cup of coffee or two.


Finally.. I have an Onan Emeralg 5500. not all that noisy, and it does not shake the Class A so as I notice.

Fact: A few years back out in an open field in the middle of a wooded area I was about 100' from the motor home as I plugged in the first of two Radio positions to my extension cord.. The Field Day chair said "You can start the generator now"

It was already running. He could not hear it.. he is a broadcast engineer by the way (I could hear it but Well.. lots of years on radios listening for signal under noise)

[BryanL]

The thing to keep in mind is that it takes time to charge a lead acid battery, They are not capacitors! It takes 8 to 12 hours to fully charge a lead acid battery under optimum conditions.

8 T105's at about 70 pounds ea is maybe 560# so, at 4 watts per lb C/5 charge rate, the optimum charge level would be a bit over 2 kW during the initial bulk stage. That sort of charging device is not very common.

Note also that batteries provide about 10-15 usable watt hours per pound. That isn't much for any bank size you can haul around in an RV.

[gbstewart]

Quote:

Originally Posted by Shadowcatche The built in Onan would be where I put my attention, vibration mounts and a decent muffler and sound deadening. The use of a good converter/battery charger in conjunction with said generator to bring batteries up to full charge and the addition of solar panels to extend the don't have to run the generator time. Last but not least conservation efforts i.e. LED lights.

I agree with this, seems adding a 2nd generator would be more of trouble then what its worth, Id spend time on the Onan, theres lots of stuff and ways for sound deading, you should pull it out and see if any mounts are broken, or rubbing on something, while its out you can sound deaden the compartment, theres lots of reading on this subject.

good luck (just my 2 cents cdn) as aways its your choice, and it will work out.

gbstewart

[DumOleBob]

Sell the generators and 4 of the Trojans and get a good solar outfit as per HandyBob and be done with it! HandyBob's Blog

Besides hanging all the weight, PLUS 20 gals of gas, on your butt end is just asking for a total disaster!!! You've got enough hardware to run a small city

[droflex]

Thanks guys!

I guess working on getting the onan to be quieter would be better 'cause it's already wired in for everything. Maybe extending the exhaust an putting better muffler(s) on and vibration proofing better would help.

I still need to get as many storable (usable) amps as possible 'cause I'm not just a weekend kind of camping guy. I might decide to go for a weekend but sometimes change my mind and stay for a week (that's where the massive amount of battery storage comes in).

The limitation after that would be propane.

As far as solar goes, I do most of my outbacking in the Pacific Northwest so I dont think that solar is really an option.

Maybe one of these days I will be able to move to a sunnier part of the country and then live it up with solar but for now I'm kinda stuck here. I'm lucky enough that my business enables me to get as far away and stay away as I do.

This is really helping me a lot!

I will read more of the replies and respond specifically.

Thanks!

[jlyon69]

Quote:

Originally Posted by droflex Thanks guys! I guess working on getting the onan to be quieter would be better 'cause it's already wired in for everything. Maybe extending the exhaust an putting better muffler(s) on and vibration proofing better would help.

I would certainly go that route if it were me, save $$$, work, lots of weight and no doubt some grief. Put your money into a good converter/charger and switch to all LED lights. If you are a TV watcher, upgrade your CRTs TV(s) to LED. I recently bought 2. Although these TVs say they're 120VAC, they are really 12VDC and come with a converter on the cord. DW has to use a CPAP at night which I configured to work on 12VDC. I have no need for an inverter.

Quote:

I still need to get as many storable (usable) amps as possible 'cause I'm not just a weekend kind of camping guy. I might decide to go for a weekend but sometimes change my mind and stay for a week (that's where the massive amount of battery storage comes in).

I understand what your saying, but you do have a generator. My thoughts are if you switch to LEDs and your fridge is going to run on propane, what's the purpose of 8 T-105s? I only have 2 T-105s and I can go a few days, then it takes several hours to bring them back to 90%. My point is, with the proper thought/planning on your power consumption, will greatly impact your power storage needs. It also seems better to run your genny a few hours every 2-3 days than needing to run it 12-16 hours every 5-7 days. I of course don't know what your power needs are....just my 2 cents and perhaps something to ponder about if you haven't considered these things.