My travel trailer's batteries were stolen and now that I have 2 new ones to reconnect them, but of course they were already properly connected when I bought the trailer and I never had a need to mess with the wiring before and I don't know how they were connected to begin with. Some of the wires were cut when the batteries were stolen and some were left in-tact. I can easily reconnect everything as far as having the proper tools and supplies to do so, but I don't know which cables go where. The wires coming out of the trailer are 1 red, 2 white, and 1 black...so first I need to know where each of those should be connected and then also how to connect the 2 batteries to one another in series. Thanks very much for any help and advice that you can offer!!Moved to Tech Issues forum from DIY.

Hi,I'd suggest using a continuity test to see which wires go to the ground.You might also contact the manufacturer of the rv.

google is the answer.http://www.google.com/search?sourceid=navclient&aq=&oq=connecting+batteries+to+rv&ie=UTF-8&rlz=1T4GZAB_enUS513US513&q=connecting+batteries+to+rv&gs_l=hp....0.0.0.44905988...........0.if not, take it to a battery place to install and repair the wires.

If you have 2 6 volt batteries than you will wire them in series, if you have 2 12 volt batteries than you wire them in paralell. the lowest amp battery or the battery with the least abilility to provide optimal power will bring the total output down to what it can handle.hope that helps

My advice is if you don't know what you are doing, don't do it. You can really mess things up if you connect them up wrong. Get someone who knows what they are doing to help, or take it to a dealer.

What year and make of trailer? What batteries? I am assuming 6v since you are connecting them in series? WIth two 6's you make a 12v battery by wiring the + on one to the - on the other. The unused posts become the + and - of a 12 V battery. But this of course is NOT the way to hook up a pair of 12v batteries if that is what you have.As was mentioned, people have done significant damage reversing polarity, or connecting to 12v's in series and putting 24V to an RV system. Proceed carefully.The ground wire(s) should show very low resistance to bare metal on the Rv chassis (with nothing powered up ideally).If it is a newer rig with the right kind of converter (what model do you have?) you can power up the converter without a battery connected (not with any disconnected wires where they can short to anything!) and the wire to it will show up at 13.x v most likely, relative to ground. That one goes to the + when hooking to a single 12v battery.Jim

connecting "in-series" batteries | Good Sam Community

18 Replies

mena661
Explorer
Jul 03, 2013
HiTech wrote:
Thanks for the follow up. Happy camping!
X2!
HiTech
Explorer
Jul 03, 2013
Thanks for the follow up. Happy camping!
uncle_ben
Explorer
Jul 03, 2013
Just wanted to give an update that I was able to use my multi-meter and tracing back the wires to figure out the wiring and connect my new batteries successfully. The two white wires are ground, the red wire supplies voltage to the batteries to charge them (reads about 13.5 volts when connected to shore power) and the black wire is also a power wire that goes to the 7-way hookup. Thanks for the diagram and website link "Pianotuna". I hooked it up the way you suggested.

Thanks to everyone who provided input and advice!
pianotuna
Nomad III
Jul 01, 2013
This is what is balanced and best for twin twelve volt batteries.

As it often doesn't cost a dime more to do this, I think it is worth the trouble.

If you wish to understand the "why" surf here:

correctly interconnecting multiple twelve volt batteries

Others may say it doesn't matter--but unless there is a compelling reason to not optimize charging and discharging why not do it the best possible way?
opnspaces
Navigator III
Jul 01, 2013
I agree that using a meter is the best way to figure out what goes where.

But you can also deduce what is what with a fair bit of certainty if you don't have a meter.

Unplug from shore power
grab a white wire in your hand and trace the wire with your hand until it changes. If it goes to a bolt or screw on the frame it is a ground wire.

Grab the next white wire and repeat the hand tracing. If it also goes to a bolt or screw in the frame it is a ground.

Now grab the red wire and trace it. See if you can identify what the wire goes to.

Repeat this for the black wire.

Where do all the wires go?
MEXICOWANDERER
Explorer
Jul 01, 2013
Maybe better taking mountain to Mohammed.

Insulate all wire ends. Plug in RV. With meter determine which wire shows 12+ and which wire shows 12-

Unless the battery wiring was a rat's nest to begin with simple logic and deduction may help to orient adjacent wires to their proper orientation once positive and negative feeds have been determined.
uncle_ben
Explorer
Jul 01, 2013
To answer your questions, it is a 1994 Cobra Sierra, 21 ft. Batteries are 12volt, so I guess they need to be in parallel, not in series, so that already helps me, but I still need to figure out where each wire goes. Thanks for your input!
pianotuna
Nomad III
Jul 01, 2013
Try these sites for more current information than the 12 volt side of life:

http://rvroadtrip.us/library/12v_system.php

http://rvroadtrip.us/library/solar_install.php
restlesswind
Explorer
Jul 01, 2013
For just about everything you need to know (and more) about RV batteries. With pictures.
"The 12 volt side of life"
http://www.marxrv.com/12volt/12volt.htm
Bobbo
Explorer III
Jul 01, 2013
ken07734 wrote:
I never checked on this but can the standard charger nuilt into the inverter/converter charger able to handle charging 2 six volt? or 2 twelve volt tied together?

No problem.