6 Volt batt wiring

megalops · Post by **megalops** » Wed Feb 18, 2009 12:20 am

Can you guys tell me what size cable I should use to paralell wire the 6 6V batteries in my new house bank?

I know I don't want any voltage drop, but the runs are really short, so I'm confused. 1/0 maybe?

Thanks

Hirilondë · Post by **Hirilondë** » Wed Feb 18, 2009 6:47 am

You aren't going to do series/parallel to end up with 12v times 3pairs?

Post by **Tim** » Wed Feb 18, 2009 7:17 am

What sort of maximum load might you have? What level of electrical equipment? If these are just jumpers to connect the batteries to one another in the proper manner (three 6V pair in series for 12V, then these three sets paralleled together, I imagine), then what size cable do you have between the batteries and the loads? If you have existing cable, then use whatever size that is.

If you're starting completely fresh with all new cabling, then you/we definitely need an idea of the sort of potential loads your system will have, and the distances involved. In any event, I think jumpers should always be the same size as the other cable runs.

megalops · Post by **megalops** » Wed Feb 18, 2009 9:23 am

yes, just jumpers, the other cabling exists and is in good condition. I'm going from two 8D to 6 6V for my house bank. This is on my 1973 36' gulfstar trawler.

The rest of my cables are mostly 3/0 which seems extreme (and expensive) for a 6" run.

megalops · Post by **megalops** » Wed Feb 18, 2009 9:47 am

I see I may have been a little confused in my terminology between series and parallel. The diagram in muchmsw's (scroll down about 1/2 way) post is the correct way to do this, right?

http://www.cruisersforum.com/forums/f14 ... 559-2.html

thanks for your help.

dmairspotter · Post by **dmairspotter** » Wed Feb 18, 2009 11:16 am

Ooops, thats pretty big!

Anyway, that's a diagram of 6 x 6V batteries connected to provide 12V power.

You WILL have voltage drop. That's physics. How much depends on

1) Resistance of the wire used
2) Current through the wire.

In a perfect world, the current in each of the blue wires would be 1/3 of the total current. The red and black wires each carry the total current drawn (not really but close enough).

However, your membership in planet perfect has been revoked and you live here with the rest of us schlubs, so be conservative, think about failure modes.

I would recommend googling "ABYC wiring requirements" and hitting a few sites.

You definitely need to know what your maximum amperage draw will be to figure out your wire size.

If I were doing this the first thing off the positive 12 lead would be circuit protection. The size of that protective device would give me the maximum current the battery wiring would need to carry. That would allow me to size the battery interconnect wiring properly.

None of the above is ABYC gospel. I am an electrical engineer, not a working man, so take the above as such.

David · Post by **David** » Wed Feb 18, 2009 11:34 am

Also, all of your wires connecting batteries either in series or parallel should be the exact same size, type, and length.

Post by **Tim** » Wed Feb 18, 2009 12:00 pm

megalops wrote:The rest of my cables are mostly 3/0 which seems extreme (and expensive) for a 6" run.

That may be, but I'd still suggest sticking with the same size. Fortunately, even with all your jumpers you're only talking about 10 or so of cable, probably.