Charging Batteries

flugelboneman · 02-01-2023, 11:57 AM

2019 Cougar 27RES: After winter storage would like to top up batteries. System is a bit different from my other RV's in that this unit has two batteries I believe connected in series. They may be 6 volt each instead of one 12. Can I charge them together? How do I hook up the charger? Would you put one terminal on the negative of one battery and the other to the positive terminal of the second battery? Or do I have to charge them separately. Thx for input.

**chuckster57** · 02-01-2023, 12:14 PM

If you have an outlet just use the shore cord with the appropriate adapter and let the converter take care of it. We use 50A to 15A adapters and 30A to 15A all the time. Just can’t run the AC.

Otherwise yes battery charger cables- positive to positive of one battery and negative to the negative if the other one depending on type and wiring.
You do need to know if it’s a pair of 12V or 6V and if 12V are the trailer leads in opposite batteries.

flugelboneman · 02-02-2023, 09:19 AM

I should have mentioned that I am using an external battery charger, as I have found the RV built in charger is usually only a "trickle" and I want my batteries topped up after a long winter storage. I do not have a power source where I store the RV, but bring it home to use my external charger. This is a new battery configuration to me, as I have had only one large battery in previous units.

jxnbbl · 02-02-2023, 09:47 AM

The short answer is that you can use the charger but you have to match the battery type/voltage with the capabilities of the charger. In my case we have various "toys" and we generally have 2-4 batteries being maintained at once. I take the batteries out of the RV as the last step to going into storage. This is what I use as it covers all the bases - LINK

gearhead · 02-02-2023, 08:40 PM

While on a trip I had what I thought was a bad onboard charger. Bought a new WalMart charger. Discovered it would turn itself off after 6-8 hours thinking the battery was bad.
Be careful what you buy…read the directions first.

**flybouy** · 02-03-2023, 08:39 AM

Quote:

Originally Posted by gearhead

While on a trip I had what I thought was a bad onboard charger. Bought a new WalMart charger. Discovered it would turn itself off after 6-8 hours thinking the battery was bad.
Be careful what you buy…read the directions first.

Yup, read the directions!
Had a friend that was of the " more must be better" mindset that bought a charger with multiple ratings. This person didn't have enough mechanical knowlege to change a bicycle tire and knew even less about electricity. His riding mower wouldn't start and someone told him the battery was dead and just needed a charge.

IIRC the charger was a 10/25/50/100 or similar. He yanked it out of the box, hooked it up and set it on 100. An hour or so later he heard a large "boom" out in his shed. Upon investigation he found a large hole in the engine cover where the battery used to be. It looked like it was shot with a RPG. He didn't bother to read the directions (or the large letters on the box) that recommended the proper setting for the type of battery or that the 100 Amp was a "boost/starting" setting.

He learned a very expensive lesson that day. Fortunately, no one was injured and nothing caught on fire.

RobertS · 02-09-2023, 09:52 AM

Quote:

Originally Posted by flybouy

Yup, read the directions!
Had a friend that was of the " more must be better" mindset that bought a charger with multiple ratings. This person didn't have enough mechanical knowlege to change a bicycle tire and knew even less about electricity. His riding mower wouldn't start and someone told him the battery was dead and just needed a charge.

IIRC the charger was a 10/25/50/100 or similar. He yanked it out of the box, hooked it up and set it on 100. An hour or so later he heard a large "boom" out in his shed. Upon investigation he found a large hole in the engine cover where the battery used to be. It looked like it was shot with a RPG. He didn't bother to read the directions (or the large letters on the box) that recommended the proper setting for the type of battery or that the 100 Amp was a "boost/starting" setting.

He learned a very expensive lesson that day. Fortunately, no one was injured and nothing caught on fire.

That one is almost unreal

**flybouy** · 02-09-2023, 11:46 AM

Quote:

Originally Posted by RobertS

That one is almost unreal

Doesn't bother me If you don't belive it. But if you want to try out charging a 10 or 12 Ahr battery at 100 amps for an hour or so I'd recommend not standing too close to it.

WJQ · 02-09-2023, 03:48 PM

If your batteries are lead acid batteries, they are 6 volts batteries if they have three battery caps. If they have 6 caps, they are 12 volts. If they are six-volt batteries, they are connected in series to give you 12 volts for your RV. One of the responses above told you to connect the charger to the + on the battery that connects to the RV power center and the - on the other battery. If they are 12-volt batteries, they are connected in parallel. Then you can connect to the + and the - on either battery.

If you have 6-volt batteries you are fortunate as that arrangement is arguably better but I won't go into why. Try Googling 6-volt versus 12-volt RV batteries and I bet you get a lot of hits. I am sure this forum has addressed that question many times.

Note, some batteries do not have caps so measure the battery voltage. If you have lithium batteries, they will be wired in parallel and you are most fortunate.

**chuckster57** · 02-09-2023, 07:46 PM

Quote:

Originally Posted by WJQ

If your batteries are lead acid batteries, they are 6 volts batteries if they have three battery caps. If they have 6 caps, they are 12 volts. If they are six-volt batteries, they are connected in series to give you 12 volts for your RV. One of the responses above told you to connect the charger to the + on the battery that connects to the RV power center and the - on the other battery. If they are 12-volt batteries, they are connected in parallel. Then you can connect to the + and the - on either battery.

Actually no matter what your battery “array” is, the leads to the coach should be at opposite ends to access the “full potential” and charging should be the same.

If you look at large motorhomes that use six 6V batteries, the leads are at opposite ends of the array and since the converter charges using the SAME LEADS, using a portable charger the leads should be at opposite ends also paying attention to polarity.

**JRTJH** · 02-10-2023, 07:10 AM

Yep, The charger should be connected to the POS terminal on one of the two batteries and the NEG terminal on the other battery, as shown in this diagram. Connecting the POS and NEG to the same battery, whether it's the battery on the left or the battery on the right, will charge the battery the charger is connected to (the PRIMARY battery) and will only provide a "slight parasitic charge" to the other battery.

To fully charge both batteries, the charger should be connected as shown in the diagram. That way both batteries are "in the charging circuit"...

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