It is very common to have two or more lead-acid batteries in parallel, with no fuses between the batteries - but you MUST have a fuse close to the batteries, between them and other wiring in the boat/vehicle. For marine use, ABYC says the fuse must be within 7 inches of the battery.
Do I need a fuse to fuse a battery?
In between batteries (unless regulations require) it is not necessary. Fusing is for wiring not so much equipment protection. The bms takes care of the battery as you said. There is a decent product that acts a a rapid disconnect and fusing, look up the mersen fuse disconnec t. There is quite a range of them for different amperages needed.
Does a string fuse protect a battery?
A: yes, when one battery in a string has a problem, it will be protected by the string fuse (so the other batteries won't discharge full power into this string). Also, the string fuses prevent overload on one of the strings, while a fuse for the complete set wouldn't protect a single string. Sorry, I might be a bit confused at the post.
Where should a battery fuses be placed?
This applies to both the power-carrying circuits and the balancing sensor wires. This is a good idea even where it is not a requirement for safety. We suggest fuses be placed typically less than 10-15 cm (8 in) from a battery terminal — the closer the better. ALWAYS place the fuse near the battery.
Is fusing a battery a good idea?
Fusing is for wiring not so much equipment protection. The bms takes care of the battery as you said. There is a decent product that acts a a rapid disconnect and fusing, look up the mersen fuse disconnec t. There is quite a range of them for different amperages needed. What is the bank powering? What size wiring as well?
How do I connect my batteries?
The additional components, terminals and wire lengths all introduce potential failure points and resistive imbalance. We would recommend the traditional short cable interconnection between the batteries with positive and negative connections at opposite ends.
Most of the current will therefore travel through the bottom battery. And only a small amount of current will travel through the top battery. The correct way of connecting multiple batteries in parallel is to ensure that the total path of the current in and out of each battery is equal.