Boat wiring question

[tanq50]

I have dual batteries in my boat, but both were dead. I pulled them out and took them home to charge. I have multiple negative wires coming directly off both batteries. I thought I had marked them correctly, but not sure now. Is there a way to use a multimeter to confirm this?

Thx in advance

 

[Grub54891]

After three posts you can post pics. Do that and let us see what you have going on.

 

[tanq50]

Well, not much to see in a pic. I have a single positive wire for each battery and 5 or 6 negative wires for each battery. I have forgotten which group of negative wires below to which positive, so that I can reconnect the batteries the way that I took them out. I'm assuming you need to have the negative and positive for each piece of equipment on the same battery.

 

[JASinIL2006]

Sounds like you need to trace some wires to see complete the circuit for battery A and which do it for battery B...

Or you could put in a simple A/B switch and a common bus bar for the negative wires.

 

[tanq50]

I have a battery switch, but I haven't had the time to rewire. The way I got the boat had all these wires connected directly to each battery. I was wondering if there was a way, using a multimeter, to see which negative belonged to which positive. Currently, I have two positives, one for each battery, and about 10 negatives, some on one battery - the balance on the other. Now that I have disconnected all the wires, and thought I had separated, but now they have fallen down and mixed up, so not sure which negative wires went to which of the two positives.

 

[Grub54891]

You could install a negative buss bar in the area, then install the negatives to that. It makes for a cleaner install and easier to service. Abyc don allow more than 3 wires on ant terminal anyway.

 

[nola mike]

If you're sure that the negatives are actually negative, you can just hook them up. If you have it wrong, those circuits may or may not work. Are the batteries completely isolated from each other?

 

[dingbat]

I was wondering if there was a way, using a multimeter, to see which negative belonged to which positive.

Shouldn't matter.
The two batteries should be tied together making both battery grounds common

 

[airshot]

Once you get it sorted out, pick up some cable ties in black and red. Tie all the black ( negative) wires together with a black cable tie, so know you know all the wires that connect to that battery post. Do the same for the positive with the red cable ties. Have done that for many years with no chance of a mixup. If you have two batteries close to each other, just add an addituonal color tie to distinguish. Example....the black and purple go to battery #2 andvthe just black only go to battery #1 etc....

 

[tanq50]

Thanks for the responses. Good idea on the color coded zip ties too.

 

[KD4UPL]

If you have 2 batteries and a 1 / 2 / both switch then all your negatives are the same. You should have a big negative cable connecting both battery negatives together. You should have another big negative cable going to the engine block. Then all your other negatives. They can go on either negative post since they are both hooked together with the big jumper; it makes no difference.