Generator battery wiring ~ Help Please!

ZMPAL · August 13, 2017

Hello everyone!

Thanks for the wonderful opportunity here! This forum is really very helpful!

I am very new to rving so I am not very knowledgeable about a lot of things. I disconnected the battery that starts the generator to get it charged and failed to take a pic of how the cables were connected. Now I am not sure which cables go to positive or negative on the battery post. Any help would be greatly appreciated! I have 5 cables coming from the RV. 3 of them are bundled together. In the bundle, one is black, one is red and one is white. There are two additional cables one has blue tape near the connecting end but it's pink inside the black casing that covers it. The other has a red tape near the connecting end and I can't see what color it is inside the casing. I have one battery. Where do all these cables go on the battery? Thanks again for any help!

ZMPAL · August 13, 2017

Hello everyone!

Thanks for the wonderful opportunity here! This forum is really very helpful!

I am very new to rving so I am not very knowledgeable about a lot of things. I disconnected the battery that starts the generator to get it charged and failed to take a pic of how the cables were connected. Now I am not sure which cables go to positive or negative on the battery post. Any help would be greatly appreciated! I have 5 cables coming from the RV. 3 of them are bundled together. In the bundle, one is black, one is red and one is white. There are two additional cables one has blue tape near the connecting end but it's pink inside the black casing that covers it. The other has a red tape near the connecting end and I can't see what color it is inside the casing. I have one battery. Where do all these cables go on the battery? Thanks again for any help!

ZMPAL · August 13, 2017

1 minute ago, ZMPAL said:

Hello everyone!

Thanks for the wonderful opportunity here! This forum is really very helpful!

I am very new to rving so I am not very knowledgeable about a lot of things. I disconnected the battery that starts the generator to get it charged and failed to take a pic of how the cables were connected. Now I am not sure which cables go to positive or negative on the battery post. Any help would be greatly appreciated! I have 5 cables coming from the RV. 3 of them are bundled together. In the bundle, one is black, one is red and one is white. There are two additional cables one has blue tape near the connecting end but it's pink inside the black casing that covers it. The other has a red tape near the connecting end and I can't see what color it is inside the casing. I have one battery. Where do all these cables go on the battery? Thanks again for any help!

Yarome · August 13, 2017

The following are "likely", but the blue and red taped cables really need to be verified.

3 cable bundle... red-positive. black+white-neutral/ground.

The two other cables are likely to your inverter, solar controller, aftermarket generator or other independently wired source/supply. This is an assumption since I know nothing about your rig or what may or may not have been installed aftermarket. Most likely is an inverter. Check your inverter inputs to see if the size/colors match and are similarly marked with tape. Most likely, the red taped cable is the positive and the blue-negative.

Let me stress... other than the 3 cable bundle, simply connecting them as above should not be done without verifying exactly what is installed and the polarities verified.

IMHO, having all of your cables connected like that is not what I would consider to be a "typical" installation so caution should be exercised.

Hopefully, your power distribution panel will be labelled. If it is... a photo would be helpful as well as a description of your currently installed components. Ie., Inverter? Solar? Factory or aftermarket generator? etc.

Yarome · August 13, 2017

"Atypical" installations always make me a little nervous.

It's also possible that the two single red and blue taped cables "could" be your batteries main cables. Probably the best course of action would be to completely isolate all of the cables, plug your RV into shower power and then test both sets of cables with a multimeter to determine which set is receiving 12v from your RV's converter. That would take away all doubt.

That's not quite as "safe" as doing a continuity test from the power distribution panel to the cable ends, but that isn't always practical since it requires partially dismantling the power center, locating the 12v cables and running wire from the cable ends to your meter to test continuity.

As long as all cables are isolated... ie., nailing/screwing each cable to a 2x4... you should be fine.

Orvil Hazelton · August 13, 2017

I may be able to simplify your problem some: If all else fails . . . read the manuals! When new, your RV without doubt came with a file of instruction, warranty and maintaince pamphlets. Check these for verification of your battery wiring. Thimk b4 u loose it up.

Devilishjim · August 13, 2017

Just guessing and by looking at the length of cables and colors I would say the two reds go to posotive and two blacks go to Negative.

It looks like the black one and small white one are tied together ? ? We cant see the end of black one.. You only removed wires from battery and nothing else ?

kb0zke · August 13, 2017

"...plug your RV into shower power..." Not sure I'd want to try that shower! <grin>

Seriously, generally red = positive and black or white = negative on 12 volt systems. There are enough variations, though, that one can't just assume. Disconnecting all power and doing a continuity check is great IF you can easily get to both ends of the subject cable with the meter probes. If not, you will need an assistant and a jumper wire. Another method that is frequently suggested is a tone set. I've not purchased one, but probably will get one eventually. Basically, you attach a signal generator to one end of the subject wire and put a probe near the other end of the possible subject wire. If you hear the tone or see the light you know you have both ends of the same wire. This can be done by only one person, rather than using an assistant, as a meter would require.

Kirk W · August 14, 2017

If you have a volt meter you can make sure that your cables are not where they can touch any metal and then connect to shore power and the positive cable will then have about +12v on it. If you remove the shore power plug you can then find the cable for the negative post by measuring from it to the frame of the RV with an ohm meter. The negative cable will measure near 0 ohms to the frame.

EDIT~~ After looking more closely at the picture, I don't consider the bundled pair to go on the same terminal as the lengths are far too different.

Yarome · August 14, 2017

56 minutes ago, Kirk Wood said:

It is pretty safe to assume that the bundled wires came off of the same battery post.

Due to the different lengths and from the bends, my take would be that those bundled wires are NOT off the same battery post, but rather positive and negative posts.

The question for me would be about the other two cables marked with red and blue tape. Are they both off the positive post leading to different devices? Positve and negative feeds for a single device? OR... are they someones idea of a wiring job and are actually the main battery cables.... and it's the bundled wires that lead to some type of device?

They "appear" to be the main battery cables, however, I've learned long ago not to trust them by appearance alone since we really have no idea of what someone DIY wiring job might look like.

Kirk W · August 14, 2017

19 hours ago, ZMPAL said:

I have 5 cables coming from the RV. 3 of them are bundled together. In the bundle, one is black, one is red and one is white. There are two additional cables one has blue tape near the connecting end but it's pink inside the black casing that covers it. The other has a red tape near the connecting end and I can't see what color it is inside the casing. I have one battery. Where do all these cables go on the battery?

I just edited my previous post as I believe that Yarome is correct about the bundled wires. I expanded the second picture and looked again.

After studying the pictures further, it looks probable that you have an inverter to supply the TV when you do not have shore power? If so, the two heavy wires not bundled are probably to it and the tape may mark positive and negative, but you need to trace them back to the other end just to verify what they are and which is positive since reversing them could cause a disaster. Most likely the red tape was there to identify the positive cable, but if you connect them wrong you could cause major damage.

The same is true for the bundled 3 wires. Since the white and black wires are of the same length, they likely go to the same post and in typical cases, red would be positive, but again there is great risk in connecting them without verifying the polarity with a meter. If you have a meter and understand it's use, you can verify where the wires go and thus the proper polarity but if you are not sure then you should probably get a professional to help as the damage that could be done by connecting things incorrectly is considerable.