Balanced Battery Wiring

Connect it the way you think is best.
Start the load.
Check voltage on each bank
Any other method of verifying "positive proof" is irrelevant.

smkettner wrote:
For the jack, connect as most convenient.
For the inverter powering the electric convection oven read the link above.

That's what I'll do. The inverter and chargers will be done by the book.

horton333 wrote:

Or is there some connection resistance besides the cables?

With short runs of #1 wire your connection to the battery is almost for sure going to be a significant fraction of the wire resistance, and if you just wing-nutted it on it could be more.....

Not wing nuts. Need a 1/2" box wrench to tighten the nuts and am using anti-corrosion conductive paste.

Afraid this is going to be a "hoser" (Canadian Redneck) job anyway. The bank that may be carrying more load by miss-wiring it this way will be new US2200 GC2s, while the other bank is a pair of 3 year old US2000 GC2s.

Put them all together in the new tongue mounted battery box during one of our lovely spring snowfalls. In my hurry, got one of the bats turned around. Boy, the sparks did fly on that one!

Sam Spade wrote:
Or is there some connection resistance besides the cables?

With short runs of #1 wire your connection to the battery is almost for sure going to be a significant fraction of the wire resistance, and if you just wing-nutted it on it could be more.....

brulaz wrote:


I'm thinking that in this case it doesn't really matter which bank I connect the pos lead from the jack to.

You are thinking right, does not matter which positive you connect the jack to.

For the jack, connect as most convenient.
For the inverter powering the electric convection oven read the link above.

Sam Spade wrote:
The jack will be operated for short periods and not very often so it probably won't make any practical difference but..........
Is there any good reason NOT to connect it "right" ??

The pos post on the "correct" battery is full up with cables and an inline fuse block. Whereas the pos post on the parallel battery is not.

And I guess I have issues with the link PianoT provided. The first example uses an "interconnecting lead resistance" of "0.0015 per link". That's about one foot of #12 ga wire. Who uses that? My batteries are interconnected with 8-12" of #1 ga, or 0.000126 ohms per foot. Or is there some connection resistance besides the cables?

And I'm certainly not talking about 100A current, as in his example, the inline fuse for the tongue jack is 30A. Although I'm also tempted to move a second cable that's fused at 60A.

The jack will be operated for short periods and not very often so it probably won't make any practical difference but..........
Is there any good reason NOT to connect it "right" ??

The battery interconnect length only matters IF there are more than two jars. When there are an odd number of batteries only method #3 will balance them and cable lengths should all be identical.

You should go with the best practise and connect all loads to just one positive post.

http://www.smartgauge.co.uk/batt_con.html

brulaz wrote:
The general rule is that when wiring two 12V battery banks in parallel, you take the pos lead off one bank and the neg off the other.

But what if the battery interconnect cabling is much heavier (and shorter) than external leads?
Does it matter as much then?

In particular, my parallel 12V banks are interconnected with 8-12" of #1 cable, and I want to attach a #10-12 lead from my electric jack. One bank already has a neg lead to frame. I'm thinking that in this case it doesn't really matter which bank I connect the pos lead from the jack to.

If the #1 cables are well attached, lock washer that 'bites', then no problem, especially given an electrical jack is only occasional use and charging is not impacted.

Using the frame as a ground also implies making sure there is no corrosion on those connections, I'd cover those from the elements.