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sbleiweiss · 12-29-2021, 06:56 AM

My charger may be failing and it will be a week or so before I can get it into a shop. If I want to put a trickle charger on the house batteries (two 6 volt deep cycle wired in parallel) how do I attach it? Also, should the coach be disconnected from shorepower while I trickle charge? Will I need a more powerful trickle charger than I use for our cars? Thanks.

twojayhawks · 12-29-2021, 07:53 AM

There's lots of battery experts on here & I'm not one of them. Maybe one will chime in. I believe you can connect your portable charge devise to either battery since they are connected making one 12 volt battery- both batts will get the charge. You could also connect to neg on one batt & pos on the other. If you have a modern microprocessor charger I would only use the lowest amp setting (maybe 2 amps) & I would unplug coach from shore power. I have the model below & it will go to maintain/off when charged so it's pretty foolproof.

https://www.harborfreight.com/2815-a...ger-56796.html

Crasher · 12-29-2021, 08:04 AM

Quote:

Originally Posted by twojayhawks

There's lots of battery experts on here I'm not one of them. I believe you can connect your portable charge devise to either battery since they are in connected making one 12 volt battery- both batts will get the charge. You could also connect to neg on one batt & pos on the other. If you have a modern microprocessor charger I would only use the lowest amp setting (maybe 2 amps) & I would unplug coach from shore power. I have the model below & it will go to maintain/off when charged so it's pretty foolproof.

https://www.harborfreight.com/2815-a...ger-56796.html

You're partly correct. With a 12 volt trickle charger, you "Must" connect the negative to the negative post of the battery that goes to the frame ground and the positive to the positive terminal of the other battery. To check that you are correct, use a tester to confirm you have 12 volts between the posts I mentioned.

FWIW, if you are hooked to shore power, your onboard inverter/charger will charge the house batteries if you have it turned on.

TonyMac · 12-29-2021, 08:15 AM

My charger failed while I was living in the rig -- bummer. Charging the house batteries is not like charging a car battery for one big reason; you are depleting the house battery charge with normal house usage while you are charging the house batteries. And when the car battery charger gets the batteries to full charge, it normally goes into float charge, trying to just maintain the charge. Mine could not make sense of the depleting level of charge, except to assume my battery was bad, in which case it threw a Bad Battery warning and quit charging. So I out thought the thing.

I connected my battery charger to a timer, one with 48 push buttons that correspond to every half hour in a 24 hour day. (IN IS ON, remember that.) I pushed all the buttons in, and then pulled out one button every 4 hours. In this manner, once connected and plugged in, the charge would recieve 120vac and start charging at full rate. Every 4 hours, the timer would remove 120vac anc reconnect it 30 minutes later. If the charger had fully charged the batteries and went into float, or even a Bad Battery warning mode, the reset would put it back into full rate charge every four hours.

Since my inverter charger wasn't charging, and I was plugger into shore and didn't need the inverter, I removed same and shipped it to a guy who rebuilt it and sent it back, better than new at half the price. I had to wire around the circuits that go thru the inverter, but that was a real easy 1 beer job.

Persistent · 12-29-2021, 08:25 AM

Quote:

Originally Posted by sbleiweiss

My charger may be failing and it will be a week or so before I can get it into a shop. If I want to put a trickle charger on the house batteries (two 6 volt deep cycle wired in parallel) how do I attach it? Also, should the coach be disconnected from shorepower while I trickle charge? Will I need a more powerful trickle charger than I use for our cars? Thanks.

Of course you mean you have two 6 volt deep cycle wired in series to make a 12 volt battery bank.

Crasher has it correct. There will be a jumper cable from the negative of one 6 volt battery to the positive of the other. There will be no other connections to those terminals. Do not connect there.

You can connect both built in charger and new portable charger at the same time if the built in charger is not badly damaged.

Post make and model of built in charger for better advice.

Charging deeply discharged lead acid batteries requires a higher capacity charger. You may have around 200 amp hours in your series bank. For fast charging you could use 40 to 50 amps. They would need 4 hours to get them usable, 18 hours for a full clean charge.

A 20 amp charger would take 8 hours to become usable and 18 hours for a full clean charge.

A 5 amp charger will take 40 hours or more.

I wish you good luck and happy trails ahead!

sbleiweiss · 12-30-2021, 07:38 AM

OP here. I connected a regular car trickle charger to the batteries. Easy to understand advice. Thanks. Just used the two posts not being used to connect the two batteries together. I understand it will take a long time. I am really just interested in keeping them from sliding further between now and next week when I take it into my electrical shop. If they actually gain some charge level, all the better.