recharging battery

[captbanjo]

For anyone who has run their batteries for extended length when no AC was available, I'm wondering...if you hook your cord into the truck and start the engine, about how long does it take for your truck to recharge a low battery? We'll be dry camping for a week next month and suspect the power will dwindle by the week's end.

[Montana_593]

I would guess several hours. You might want to rent a small generator for that task, it would probably be cheaper than running the tv that long

[Montana_1683]

I haven't had to charge the RV battery, but I know that it takes less than a minute to charge a car or truck battery with the engine running. It you plan on using the battery as a main electricity sourc; I would look into adding a 2nd battery, hooked in parallel not series. Or as stated earlier look into getting a generator to provide electricity, that is if you are going to boondock a great deal.

Gary

[Montana_657]

It takes a minute to recharge a full battery after starting but considerably longer to rechage one that has been drained. A deep cycle takes longer still, it must pass through boat "float" and "adsorption" charge states.

The TV battery is hooked to the alternator with a #6 AWG copper wire about 6 feet long. The RV battery by 20 feet of #14AWG wire with a 30 amp fuse.

So, lets say you draw 20 amps for one hour from the RV battery. The TV will probably charge at about 20 amps, so on one hour draw down, one hour charge up... but wait... nothing is 100% efficient.

If you manage say 50% efficiency, a one hour draw down would take two hours to charge back up. Now, you could speed that up a bit via heavy duty jumper cables..... or you could plug into a generator and let your converter chage things up at 50 amps.

[sreigle]

Wayne and Cathy, make sure your truck has the battery isolator and has the setup to charge the coach battery. If it does it will probably be listed as part of the tow package. Not all tow manufacturers' tow packages have this ability from what I've heard. I know the Ford does. Maybe the GM and Dodge guys will check in with whether those brands have this.

[Gary Swenson]

Steve and anyone else, you mentioned making sure the truck has a battery isolator. I have a 04 Ford F250 as you can see by my profile. I have the tow package but don't see this listed. I have wondered about truck issues if I were to hook up the truck while I still had the Montana pluged in. Could I hurt the truck. I also just got a generator to carry in the truck and had thought about bringing a plug up to the pin box and going down the road with the generator running the a/c so the 5er would be cool when you stopped for the night. Are there issues in doing this? I think I'll formalize this question a little more and start a new thread to make sure and reach the full membership viewing. Thanks Gary

[Montana_381]

quote:Originally posted by sreigle
[br Maybe the GM and Dodge guys will check in with whether those brands have this.

Not on my '03.5 Dodge: I made the mistake of leaving my truck connected electrically to the trailer once and had to have its batteries recharged enough to get it started.

My "isolator", now, is an unplugged connector.

BTW, recharging the house battery [-ies] from the truck is best done with a pair of very heavy-gauge jumper cables and about an hour and a half per battery of engine idling. Most truck alternators will provide ~60A to ~75A or about what an "industrial" charger can provide.

If there's any potential for really draining the house battery[-ies], they'd best be Deep Cycle batteries since the std. ones will be ruined if they go flat. [BTDTWOTTS!]

That's why I went with 2 parallelled 115AH Deep Cycles.

[Montana_657]

You ruin deep cycle as well if you run them flat. That is why your inverter senses low voltage and shuts down between 10.5 and 11 volts.

Deep cycle means the battery has been optimized for long charge / discharge cycles. A normal auto battery has been optimized for a quick burst of starting current, but cannot take long slow discharges as well as a deep cycle.

By the way, a deep cycle will start just fine. When our RV batteries weaken, they move to various machines around the yard while the RV gets new ones. They die a nartural death from old age in a mower or some such warm weather application.