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BlueThunder4 · 01-31-2020, 06:00 PM

Ok so disclaimer, I know absolutely zero about electricity or electrical theory. That being said I started what I thought would be an easy task of replacing the factory lead acid house batteries with 2 AGM Optima blue top batteries. There are quite a few wires so I took pics of the original set up and labeled the wires as well. I got everything hooked back up and came to the last wire that has one end labeled pos and the other neg??? Meaning one end goes from the pos terminal of one battery to the neg terminal on the other?? In my simple mind this sounds like a no no but does this sound correct? I thought you were never supposed to connect a positive end of one battery to the negative end of another battery. Please help!

WatchMeRV · 01-31-2020, 06:15 PM

First I would make sure you have two 6v batteries. This is normal since the batteries would be wired in series. In series the voltage will be 6 volts × 2 batteries = 12 volts. Match your photo exactly and all should be ok.

BlueThunder4 · 01-31-2020, 06:17 PM

Thanks, both the originals and the replacements are 12v?

bigchick · 01-31-2020, 06:17 PM

were the batteries you took out 6 volt or 12 volt? are the ones you are putting 6 volt or 12 volt?

with 6 volts you connect positive of one battery to negative of the other via a jumper cable. you connect to battery cables to the non jumpered positive terminal of one battery and the negative to the unjumpered negative terminal of the other.

with 12 volts you connect two jumpers between the batteries. one is positive to positive, the other is negative to negative. you connect the battery cables to the positive of one battery and the negative of the second battery.

hivoltage98 · 01-31-2020, 06:17 PM

If the wire in question is a single wire that runs between the 2 batteries then you had 2 6volt batteries and your replacing them with 2 12 volt batteries.

Ljwt330 · 01-31-2020, 06:21 PM

Connecting the neg of one battery to the pos of another is known as wiring in series. It effectively doubles the voltage of each single battery by creating pair that provides twice the voltage. Two six volt batteries wired this way creates an effective single 12 battery.

If you replaced two batteries, they were likely six volts each but your coach is a 12 volt system. Wiring them in series, using the cable you found, pairs them into a 12 volt power source.

Your post is not clear as you state both og and replacements are 12 volt, but as a question. If the old batteries were 12v, there wouldn’t be that cable you found unless you have a 24v system—highly unlikely.

Check the batteries you installed and tell us the voltage. If you don’t know, count the caps on each one—3 caps is six volts, 6 caps is twelve volts. Post a picture of your batteries as they are wired. If you are at all unsure, do not make the final connections to chassis ground until you are certain of the battery voltages and the wiring.

BlueThunder4 · 01-31-2020, 06:22 PM

In the pic it is the only single wire connecting the two posts (lone wire on each post) one is pos the other is negative on opposite battery.

BlueThunder4 · 01-31-2020, 06:24 PM

Uh oh maybe the original were 6volts? Hope i didn’t fry the coach! They are the same size as a 12v so I assumed they were 12v 🤦*♂️

BlueThunder4 · 01-31-2020, 06:27 PM

Batteries original are Harris GC2RV

iowaone · 01-31-2020, 06:27 PM

Stop tell you figure out what you are doing.

iowaone · 01-31-2020, 06:29 PM

They certainly were 6 volt batteries. The three caps are a dead give away. The new ones will work but the need to be wired differently.

BlueThunder4 · 01-31-2020, 06:31 PM

Thanks for the help, you are right 6volts. I never turned power on but did have it connected for a second before taking it off. Hopefully I didn’t just fry the entire electrical system by sending 24v it’s way.