Wire gauge for parallel battery jumpers.
Method 1 (typical):
Wiring 12V 100 AH batts in parallel + to + to + to load yields 400 AH @ 12 V. Negatives connected in the same way to ground. Seems to me the first jumper needs to carry 100 A, the second 200 A, the third 300 A, and the connector to load 400 A to supply a 3000W inverter (with T450 fuse within 7 " of the final battery in the string). Camping World installed a 2 battery system and used 2/0 for the jumpers and 4/0 to load to handle maximum static load of 3000w/12V=250 amps and up to 400 start-up amps.
I replaced the 2 lead acid batteries with 4 12 V 100 AH lithium iron phosphate batteries. This option connects each positive pole to a bus, then the bus to load. Same for the negatives. Each jumper would then only need to carry 100 A (unless one or more of the jumpers connections fail). This was recommended by the manufacturer of the batteries, since the terminals are tightly packed in these 4 cell batteries and better to run each lead straight off the poles rather than try to use jumpers between poles as in method 1. The jumpers are 2' total length (positive plus negative leads together) to the buses. The manufacturer recommended 6 AWG, which seemed small. I use 2/0 for the jumpers and 4/0 for the buses to inverter.
Would appreciate comment, corrections, criticism(s)
THOR TR23 RV