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Bosch ebike battery communication protocol

I'm trying to repair a bosch ebike battery (specifically a "powerpack 400").


The battery cells are all in perfect condition, but the BMS board has died. so I need a new BMS. (pretty much every single component has been fried)


Here's the problem: the Bosch BMS has an extra 3-pin connection that allows it to communicate with the ebike drive system, so using a normal "dumb" BMS board from Amazon or Aliexpress won't work, since of course the bike will only work if it can communicate with the battery.


I don't think I need to mention that of course, this Bosch BMS cannot be obtained, even by a proper Bosch certified bike shop. I've been trying to hunt one down for weeks now, without success. 



Now because I don't want a perfectly good battery to go to waste and a new 500+ euro unit to be bought, I really want to fix this. What I need to do is somehow fake the communication from the BMS with some kind of microcontroller that I can put in the battery. I'm quite experienced with electronics and microcontrollers, but I have no clue what kind of communication protcol the bosch system uses. I've seen some comments online that the battery uses CAN bus, but even if that's true that's still too little information to spoof the BMS. Therefore I'm hoping someone here knows some more details about the communication protocol these battery packs use or where to find this info, so that I can try and rig something up to make the bike think there's a proper Bosch BMS in the battery.


Thanks in advance!

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