Help with older BIONX 36 V battery rebuild with bms added

notcynical

New Member
Region
Canada
Hi,
New member here and really appreciate the forums. I'm trying to rebuild an older 36V Bionx battery with a 5.2 board and wanted to add a proper BMS balancer since the original doesn't have that function. No problem building a 10s battery and wiring the balancer to it, but now I'm at the point of having reconnected to the Bionx board and need some help. I tried to follow a Dr Battery youtube video but he goes too fast at the important spots and doesn't properly show and explain his work so this is the configuration I think he did, but not 100% sure. When I tested this version with the pack I built, the charger went into charging mode and when I hooked up the battery to the bionx dock it powered up the g2 console and functioned properly. I'm just hoping there's a few battery experts on here who can tell me if I've done this BMS addition right or If I've created a potential fire hazard.

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Cormode

New Member
Region
USA
Hi,
New member here and really appreciate the forums. I'm trying to rebuild an older 36V Bionx battery with a 5.2 board and wanted to add a proper BMS balancer since the original doesn't have that function. No problem building a 10s battery and wiring the balancer to it, but now I'm at the point of having reconnected to the Bionx board and need some help. I tried to follow a Dr Battery youtube video but he goes too fast at the important spots and doesn't properly show and explain his work so this is the configuration I think he did, but not 100% sure. When I tested this version with the pack I built, the charger went into charging mode and when I hooked up the battery to the bionx dock it powered up the g2 console and functioned properly. I'm just hoping there's a few battery experts on here who can tell me if I've done this BMS addition right or If I've created a potential fire hazard.

View attachment 98511
I don't see anything particularly wrong with the approach. Your biggest risk will be an accidental short in the new wiring, so carefully check for pinch points as you reassemble.

I assume the new BMS also has the ability to cut off the charger if any one cell goes over 4.2.

You drew the positive to the new BMS as a single line. The label suggests it is actually 10 lines, which is correct.

There is something to be said for routing the negative line to the original BMS through the new BMS P- port. The old BMS has a low voltage alarm / cutoff, but that is whole pack, the new BMS should also be able to cut power on a single cell group going too low.

As I recall the thermistor on the original BMS is just wired to the charge port so the charger can back off current in response to high temp.