BMS wire length question

[Ldc_NH]

Hello

Do BMS wires all need to be the same length? I have built four 48 volt batteries to date and always made all wires the same length. The process is time consuming and you end up with lots of extra wire to hide. I have done the same thing with my separate active balancers, again time consuming and lots of extra wire. In all cases I had used Overkill 100 amp BMS and a separate 5 amp active balancer.

I am about to build some new batteries, this time I will be using the JK invertor BMS 150 amp with 2 amp active balancer built in. I would really like to make all wires just long enough to meet up with their prospective batteries and avoid adding a lot on extra wire. Can I do this?

My understanding of the battery positive and negative run to the busbar and charge controller should be the same length for all batteries. Is this still correct?

Ldc

 

[LakeHouse]

I would really like to make all wires just long enough to meet up with their prospective batteries and avoid adding a lot on extra wire. Can I do this?

Yes, this is fine. These wires main job is just measuring voltage, which they do with no current flowing, so length and resistance don’t matter. And even when there is some current for balancing, the JK BMS will stop current flowing to measure voltage, then restart the balance current.

My understanding of the battery positive and negative run to the busbar and charge controller should be the same length for all batteries. Is this still correct?

This is less important for LFP than it is for Lead-acid. You’ll still find lots of militant opinions here that they must all be the same, but in my personal opinion in most cases for LFP if the difference is reasonable and you have appropriately sized wiring, it’s not going to matter much.