We are new to motorhomes and have a 35' 1988 Regency. When the house batteries are drained, should the generator charge these back fully? How long should this take? I've been told 30 to forty minutes but fully charging them by connecting to shore power takes overnight.

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Originally posted by Keith Hopper:
We are new to motorhomes and have a 35' 1988 Regency. When the house batteries are drained,

The house batteries should never be drained. Every time they are drained, their life is shortened by a large amount. The less the batteries are drained before recharging, the longer they will last. However, having enough battery capacity to have low drainage takes up money, weight and space. A good compromise is to have a battery bank that is typically drained down to 40% to 60% state of charge. Some people have a hard rule of "never go below 50%".

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should the generator charge these back fully?

Yes, but once a battery is charged to 80%, the charging amps fall way off and it takes much longer to get to 100%, wasting fuel and making noise. When we are out for a long time, I charge mine only to 80%, and bring them up to 100% only once a week or two to keep the sulfation demons at bay.

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How long should this take?

This depends on the depth of discharge, the temperature and the charger. A deep cycle battery should no be charged above 25% of its capacity, but some sources will state a rate of half of that. The safe rate actually depends on the max temperature of the battery during charging more than anything else. There are rules of thumb out there, but charging time is best learned by experience with your batteries, your depth of discharge and your charger.

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I've been told 30 to forty minutes

Unlikely.

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but fully charging them by connecting to shore power takes overnight.

Yeah, that sounds ballpark.

I sould mention here that for boondocking, solar is really nice, and helps your batteries last a long time. We boondock as long as two months at a time, and only run the gen when the sun is blocked.

The expense of solar is balanced by its extension of battery life and the ability to have a smaller battery bank. Additionally, it is becoming more and more expensive to run that genset. We have taken to dragging an itsy-bitsy-teenie-weenie yellow-polka-dot EX650 Honda with us to save fuel when under trees. Well, I was lying about the polka dots (my fingers ran away with themselves). But the Honda is yellow to avoid theft.

And the convenience and quietness has gotta be worth something.

Your genset charges at the same rate as your house will as the same charger is used. So if it takes all night to recharge on electricity it will take that long on the generator.

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Originally posted by Gary Carter:
Your genset charges at the same rate as your house will as the same charger is used. So if it takes all night to recharge on electricity it will take that long on the generator.

Some gensets (and portables) have a dedicated 12-volt charging output, which is not usually very much. I believe the one on my Kohler Klanker was rated at 8 amps or so. It only reached full output if the batteries were really low. The genset 120V output powered the converter, but it charged the batteries hardly at all, as stated in the manual in my Barth binder. I rewired things so the genset 120 volt output feeds the charger/converter that replaced the original.

But, All Barths Are Different.

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Originally posted by bill h:

But, All Barths Are Different.

I think that is the truest statement I have read !!!!!!!!!
Nick

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Originally posted by Nick Cagle:

quote:

Originally posted by bill h:

But, All Barths Are Different.

I think that is the truest statement I have read !!!!!!!!!
Nick

Know what, Nick?..............I had a Fleetwood almost identical to my neighbors, and would look at mine for comparison when I was helping him with wiring stuff. They were way different. I think each Fleetwood employee had his own way of doing things, and as long as it worked, no one cared. That could explain their unwillingness (or perhaps inability) to supply a wiring diagram.

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Thanks for the advice. This is very helpful.