[jobsdone]

Hey folks,

so I got this battery recently. It is from a Tier scooter -- a Swap Battery Ninebot NFBP4814B 13INR22/71-3.

My multimeter shows no significant voltage at the cables. I assume that the BMS need to be activated. Does anyone know how to do it?

[jobsdone]

I made some progress:

If I connect the black wire (GND) to the white wire, the multimeter shows shortly after 48V but drops it after 2-3 seconds. I guess this is something like an activation line? Maybe the yellow and green wires expecting some (CAN?) messages to actually activate the power output persistently? Any ideas?

[alkyrion]

About that battery: The whole scooter runs on a CAN bus, and as such, the battery needs to be activated via that bus.
Normally, this is how the thread would end.

However, I am reverse-engineering one myself, so here's what I can tell you so far:
The whole battery is cast into a brittle silicone, so it's 100% waterproof and an absolute b*tch to open. I spent a whole day on it.

Luckily, they didn't secure the STM32G0B1 (that is the main microcontroller) and even left a debug header on the PCB.
This means I was able to dump the firmware, and I'm currently working on reverse-engineering it, as soon as I know how to talk to it via CAN, I'll post an update.

[alkyrion]

Oh, and the small three cables are CAN high, CAN low and CAN ground. CAN ground is white, but I'm not sure about the other two, but that should be solved with a quick google search.

[jobsdone]

Amazing! Thank you for clarifying.

Btw.. CAN has no "ground". CAN is a differential signal. You only have / use CAN high and low. I think the white cable is the activation line.

Can you please share the firmware dump with me. I would like to help you with the reversing.

[aaronbrimmer]

Any update on any progress on the CAN? I'm in the same place and got one of these batteries.

[jobsdone]

I haven't made any progress since @alkyrion doesn't share the firmware dump.

[Y0SH1zzzx]

Actually to get it to activate is easy, connect yellow and white wire to the red positive one and green wire to the black one that way you will be able to use the battery.

[jobsdone]

Are you sure this won't grill it?

[Y0SH1zzzx]

I've had 2 of them and it has worked, just don't short plus and minus and it doesn't matter what you do with those other ones.