What gauge wire needed to parallel 12v deep cycles

Use a dessert spoon:)

Refer to Lifeline's comments about intercell connectivity measures in milliohms. That's why the company demands start and finish cell terminations be made with phosphor bronze.

Before the "who cares?" comments start, I lost a 120 dollar Johnson Controls battery due to a flawed intercell connector. Pretty sad for a 4 month old battery.

markchengr wrote:
I wonder if anyone knows the equivalent AWG size (ampacity) of the connectors between cells in the average battery? Could they be the weakest link in a super sized cable arrangement for multi battery hookups? Food for thought. -Mark.

I suspect that the ampacity of a battery's cell interconnections is at least as large as either the maximum charging rate the battery can sustain, or as large as the battery can deliver to a load ... whichever is largest.

Just a guess on my part.

I wonder if anyone knows the equivalent AWG size (ampacity) of the connectors between cells in the average battery? Could they be the weakest link in a super sized cable arrangement for multi battery hookups? Food for thought. -Mark.

pnichols wrote:

wa8yxm wrote:
You use at least the LARGEST cable hooked to the battery.. Figure either battery may be called upon to deliver the total current of the load should it's partner fail "High Resistance" so the biggest cable is the jumper size.

That's almost the perfect correct answer.

Since my two 12 volt RV batteries are hooked up in balanced fashion, I used DOUBLE (two each) large cables between the negatives and DOUBLE (two each) large cables between the positives of the two batteries to ensure that the balance between them was even closer to being absolutely perfect.

The goal is to have two (or more) 12V batteries function as one larger 12 volt battery under all conditions - of charging them or drawing current from them.

The large gauge cables I used were pre-made short ones with lugs on each end like what you can purchase at an auto parts store. They weren't expensive.

I was doing some work for a friend last night who builds auto electric parts. In one of his trash tubs I found 4- 4AWG cords with teh ring ends on them. Two cords were about 15" and two were about 2'. A friend who is an electrician told me the 4 AWF is good for 1000 watts. When I I told him I had a 1200 watt inverter that could take a 2400 surge, he suggested I used two cables per terminal.
Later in the night I found a 30" piece of 3/0 Heavy duty welding cable

wa8yxm wrote:
You use at least the LARGEST cable hooked to the battery.. Figure either battery may be called upon to deliver the total current of the load should it's partner fail "High Resistance" so the biggest cable is the jumper size.

That's almost the perfect correct answer.

Since my two 12 volt RV batteries are hooked up in balanced fashion, I used DOUBLE (two each) large cables between the negatives and DOUBLE (two each) large cables between the positives of the two batteries to ensure that the balance between them was even closer to being absolutely perfect.

The goal is to have two (or more) 12V batteries function as one larger 12 volt battery under all conditions - of charging them or drawing current from them.

The large gauge cables I used were pre-made short ones with lugs on each end like what you can purchase at an auto parts store. They weren't expensive.

mrad wrote:
What gauge wire do I want to parallel two deep cycle group 27 batteries? The system will run through a 1200 watt inverter.

Thanks

Length of cable run can be as important as AWG...Consider ‘upsizing’ your inverter cables to avoid a re-work and sad case of morning after sickness... Been dare done dat...

mrad wrote:
What gauge wire do I want to parallel two deep cycle group 27 batteries? The system will run through a 1200 watt inverter.

I use these:

https://www.amazon.com/gp/product/B00F59NKH6/ref=oh_aui_detailpage_o07_s00?ie=UTF8&psc=1

Haven’t seen it mentioned, but you should hook the positive to one battery, and the negative to the other, balancing them. This will negate the load being on one battery issue.

On edit, it won’t totally negate that, as there could be a high resistance between the cable and battery, but not cable and cable.

This tutorial may be of some help. 12v side of life.

I got this some years ago and it is still my "bible". It was written in 2002, but by then they had things pretty much as they are now for battery charging etc. Go for it!

http://www.bestconverter.com/Books_c_67.html