Charging with two BMS, one not powered

Alexand

New member
Joined
Apr 17, 2020
Messages
4
Hi,

Q1: Can I connect my ebike battery without-line-balancing-BMS to a second, completely different, line balancing BMS in parralel?

I have a battery pack (Gazelle innergy orange) with 2 seriously degraded parallel groups (0V and 0.5V, while rest is 3.2-3.5v). I want to first try bringing these back to life and then use line balancing to keep the pack healthy with second BMS to only charge. Then keep original one to power motor because it has data connection with it.
Q2: Can I use a one cell charger to the broken group while the pack is still connected to a BMS?

If bringing the pack back to life does not work I need to replace the cells without disconnecting the BMS or it needs to be coupled again to the bike by SW that I don't have (something early-Gazelle ebikes specific I read). One battery will only work with one bike.

Q3: If I do connect both in parralel, do both need to be powered? Or can I only power the line balancing one to charge?
There are many threads on using 2 BMS in paralel or series to achieve higher charging current or voltage, then both are powered.

Any advice on this problem or other questions I should be asking?

Btw.: Don't buy a second hand gazelle innergy orange. Non balancong BMS, coupled with one bike by dealer, water can get in to battery lock mechanism (plasic block on insde broke off without my tinkering started), inside everything is stuck together with 4 silicone lumps on edges and the length of the pack is not supported in middle at the the connections (though seems to have held well), some connection seem not well insulated enough to my inexperienced eye.

Thanks in advance!
 
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