I have a drop-in Lithium (100 amp BattleBorn) under my Van's driver's seat along with 75/15 MPPT, distribution fusing, BMV 702 etc, all packed in there.
I am now adding a second battery which will go under the passenger seat and so I will have to run cables under the carpet to connect the two batteries in parallel.
I know that I need to reduce the resistance between batteries as much as possible, I am looking into running multiple #4 cables to keep the bulk under the carpet acceptable.
I also believe that due to the routing, that I should fuse the positive on both ends that connect the "remote" second battery to avoid any potential danger due to shorts that may occur in accidents or whatever. If the two batteries were adjacent, I would not consider fusing.
Does this sound correct? I'm thinking of using an 80 amp terminal mount fuse off of the new battery and then adding a similar rated breaker where the linking cable connects to the "old" battery under driver's seat. This will also allow me to disconnect the two for any maintenance work and to give me a chance to charge each separately on ocasion to make sure that both are topped off and get their cells balanced correctly.
The rest of my system is fused already between the "old" battery and the house wiring charging etc.