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. ThanksThe longer term issue is making it a true disconnect.

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.

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.

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?

SCVJeff wrote: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?I know that my disconnect doesn't totally disconnect because the carbon monoxide tester and one other alarm is on after I flip the disconnect. If I leave it for more than a week (and usually there isn't power to plug in to) I pull the battery cables on both sets of batteries. This also makes sure I look at my batteries all of the time. Bill

You said you have a bank of 4 six volt batteries.But you really have TWO 12 volt batteries (More on this in a bit)however you want to know if there is a simple way to charge them.That is easier to answer: YES, in fact there are TWO ways to recharge themONE: plug in and let the converter do the job it was designed to do.Two, Hook up an external portable SMART charger.. in both cases you treat the battery bank as a single 12 volt battery bank, which it is. Now, the comment about how you have 2 12 volt batteries....Each pair of six volt batteries -{6V}+-{6V}+ = 12 voltsConsider the pair as a single battery (12 volt) for all purposes except removal and replacement... (Replace both at the same time, but you need not lift them both together).For many, you put in two six volt GC-2 you get 12 volt at 220-230 amp hoursYou try to pick up a 4D (also 12 volt at 230 amp hours) you get a hernia(Ok, I can pick up a 4D but no way in creation I can wrangle it into the battery tray).

How to charge a bank of 6V batteries | Good Sam Community

13 Replies

RV_4_2
Explorer
Dec 29, 2014
Thanks guys, I appreciate the help. I will be putting a charger on it asap.
As has been surmised, the disconnect is for the house batteries but it is not doing a full disconnect because of the CO/smoke detector was still living and let me know when it was low on power. I will be working on a full disconnect in the near future.
And thanks on the info for charging. I thought that I could charge the bank as is but was not 100% sure. And yes they are 6V deep cycle batteries in a series/parallel arrangement.

Sully, good advise, I was going to hook up the charger to the cables that connected to the motorhome. I would imagine they are the same as what you are telling me.

Pass, I know the detectors are not wired to the chassis battery because I have installed a disconnect on the chassis battery and it has been disconnected for a while before this problem. I had installed that disconnect because there was a draw on that also.
Pass42
Explorer
Dec 28, 2014
I think that your carbon monoxide & propane detectors are wired to the chassis battery, as are your steps.... therefore, they won't shut off with the disconnect switch, which should only be for the coach (house) bank
Sully2
Explorer
Dec 28, 2014
Hook negative charger cable to a NEG terminal closest to the coach lead....BUT....hook the positive charger lead to a POS terminal farest AWAY from the coach
KD4UPL
Explorer II
Dec 28, 2014
Don't over think it. What your 4 6v batteries are is one large 12v battery. Just hook up a normal 12v charger and let it do it's thing.
Golden_HVAC
Explorer
Dec 28, 2014
Do not charge the 6 volt batteries separately, they will charge all 4 at once in about 2 days.

You might need a portable charger to 'start' your RV charger, or your RV charger might be bad, leading to the low voltage. If plugging in the RV battery will not bring the meter from 'low' to 3/4 or full in a short time, then it might not be working, or might not have sensed the 12 volt power and start charging.

Your RV charger should be rated at between 45 and 60 amps. If it is only rated at 30 amps, consider replacing it. Normally the RV chargers are rated at many more amps than a portable charger.

Good luck!

Fred.
2oldman
Explorer II
Dec 28, 2014
RV 4 2 wrote:
Or do I have to charge each battery individually?.
.
no
CA_Traveler
Explorer III
Dec 28, 2014
Use an automotive charger to charge the batteries.

Are you describing a disconnect switch near the door which is know as the salesman switch and doesn't disconnect everything?
SCVJeff
Explorer
Dec 28, 2014
Trackrig wrote:
SCVJeff wrote:
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?

I know that my disconnect doesn't totally disconnect because the carbon monoxide tester and one other alarm is on after I flip the disconnect. If I leave it for more than a week (and usually there isn't power to plug in to) I pull the battery cables on both sets of batteries. This also makes sure I look at my batteries all of the time.

Bill
the reason i asked te OP that question is I have what appears to be a main disconnect as well, but all I can tell its removing is the engine and transmission CPU, both drawing power when parked. The coach comes from a different feeder.
wa8yxm
Explorer III
Dec 28, 2014
You said you have a bank of 4 six volt batteries.

But you really have TWO 12 volt batteries (More on this in a bit)

however you want to know if there is a simple way to charge them.

That is easier to answer: YES, in fact there are TWO ways to recharge them

ONE: plug in and let the converter do the job it was designed to do.

Two, Hook up an external portable SMART charger..

in both cases you treat the battery bank as a single 12 volt battery bank, which it is.

Now, the comment about how you have 2 12 volt batteries....

Each pair of six volt batteries -{6V}+-{6V}+ = 12 volts

Consider the pair as a single battery (12 volt) for all purposes except removal and replacement... (Replace both at the same time, but you need not lift them both together).

For many, you put in two six volt GC-2 you get 12 volt at 220-230 amp hours

You try to pick up a 4D (also 12 volt at 230 amp hours) you get a hernia

(Ok, I can pick up a 4D but no way in creation I can wrangle it into the battery tray).
Trackrig
Explorer II
Dec 28, 2014
SCVJeff wrote:
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?

I know that my disconnect doesn't totally disconnect because the carbon monoxide tester and one other alarm is on after I flip the disconnect. If I leave it for more than a week (and usually there isn't power to plug in to) I pull the battery cables on both sets of batteries. This also makes sure I look at my batteries all of the time.

Bill