Trouble hooking up battery.

[tommymsw]

First let me start by saying I have done my work and know how to hook up house batteries.
Second, let me say that I just have an old tiny RV. It is not much, but it is mine.

So I just bought it this winter and have been fixing it up. Now it is summer and I want to put a new house battery in. But I have no idea what wires go where.

I am not overly worried as I may blow a fuse or two figuring it out, but just wanted some experienced advice...

I am guessing that the 2 white and the red wire would connect to the POSITIVE terminal and the black wires that attach to the side and come down go to the NEGATIVE.

But there is ONE more black wire (lowest wire in the picture) that is not connected to the others. I am assuming it is STILL a negative, and that all 3 black wires are negative and the red and 2 white are positive. That would mean 3 negative and 3 positive.. so my math works out. 🙂

Maybe the red wire and the FREE black wire are the charging wires?

Does anybody think I am wrong?

[beemerphile1]

Factory wiring, white is negative and every other color is positive. In an older RV, any color could mean anything, trace the wires.

[opnspaces]

RV's are typically wired like a house. Black and red are positive and white is negative. BUT in your situation you will probably have to get a meter since you can't easily trace the wires back to the frame.

[wrgrs50s]

Looking at your photo, the black wire with the yellow ends are going to a small circuit breaker. That would normally hook to the positive terminal and go back to your 12v power converter to charge your battery. The only way to know for sure is to follow the wires back to the converter and bus bar. The bus bar should direct 12v to your other lights, fridge circuit board, or any other 12v required appliance. If you hook it up backwards it will blow the fuses on your 12v power converter, so a little more exploring may be required.

[kerrlakeRoo]

Can you get the engine started? If so, wouldn't that tell you which was the positive wire for charging, as well as allowing you to identify the grounds.
If you label what each wire shows voltage + or - with the engine off, then check again with it running, wouldn't the isolator attempt to send some power to the absent batteries letting you isolate the first couple of leads.

[tommymsw]

The only way to trace the wires would be to tear the entire floor up, even the sub floor. The wires drop down into the floor at the fuse box and then just appear in the battery box.

[tommymsw]

And the RED is negative too then? So I would be best to assume the black wires are the positive and the 2 white and 1 red are negative?

[Lwiddis]

Trace the wires as Corvette suggested. Never know what a previous owner might have done.

[KD4UPL]

Very likely the whites are negative.

[corvettekent]

My guess is the black wire that is connected to the circuit breaker is a positive wire and the two white wires are ground.

You really need to trace each wire to see where it goes. Any other way is just a guess.

[tommymsw]

https://photos.app.goo.gl/OdAFaFCpB9xOSsS72