Forum Discussion

Explorer

Dec 28, 2014

How to charge a bank of 6V batteries

Well, I recently found out that the battery disconnect on my MH house batteries really does not fully disconnect the batteries. Kind of frustrating considering you would "think" that a battery disconnect would "disconnect" the batteries from whatever it is hooked up to.
I had my motorhome unplugged for a while and heard the CO2/smoke detector beeping yesterday like it has a low battery. Since it is hard wired, I decided to check on it and my house batteries were registering about 8 1/2 volts. I tried connecting my MH to shore power and letting the onboard charger work its magic but I got the indication that it would not charge due to the voltage being too low on the house batteries. SO, I need to charge them. I thought of looking at what people do to winterize their MHs but figured, I could get a better charging answer here.

I have a set of 4 6V house batteries for my motor home and am wondering if there is a simple way to charge all 4 at once.
Can i hook up a charger to the connections that feed the motor home and set the charger to 12V and let it slowly charge the batteries since the MH sees 12V? Or do I have to charge each battery individually.
I'm not opposed to individual charging but I am looking for an easier way taht wont take as long since I have to monitor the charger more closely.

Any help would be appreciated. Thanks
The longer term issue is making it a true disconnect.

Class A

13 Replies

SCVJeff
Explorer
Dec 28, 2014
Batteries can drop below 10.5 and survive, but not as a regular diet.
What makes you think the disconnect isn't a full disconnect, and why not? Is that the engine/ transmission (only) switch?
Canadian_Rainbi
Explorer
Dec 28, 2014
At 8.5 volts I would think that the batteries are toast. If the onboard charger won't do it try a separate automotive charger, 40A or or so (10% C). It may well give you an error after several hours since it would not be designed of 400+ AH of battery. Just start it again. OR take two out of circuit and charge 2 at a time to get them up then reconnect and charge the entire bank.

Check the electrolyte level: Make sure the plates are covered. If they are, DON'T add water even if low. If low (but plates are covered) charge, then add water and charge again.

However, as I said at the beginning, they are probably severely damaged. Wish you luck, please keep us posted as sometimes with batteries, magic happens.

The best way to keep the batteries happy is to keep the onboard charger on. (Assuming it is a good three or four stage charger). Second choice is charge fully (check SG) then pull the negative connectors. A fully charged battery with no load will last for months. I pull the negative on my car in November and it starts first try in April.
WyoTraveler
Explorer
Dec 28, 2014
I leave my MH plugged in all the time. I check the water periodically. It is hard on batteries to allow them to run down.