Bosch Powerpack 400 - Never seen strange BMS behavior

[Fric]

Hello,


I have a Bosch powerpack 400Wh that simply does not accept charge neither receives charge.
I've opened it and it has a really strange behavior, something I’ve never seen previously on a Bosch BMS.


The problem is the following: If I connect the pack to a bike, the bike does not turn on. If I connect the pack to a charger (already tested with multiple chargers) it starts charging for 1 second (i can measure the voltage going up) and it immediately stops charging.


I was able to shot some pictures and some videos of it to better clarify what is happening.


On this video I show the full procedure:

1. Connecting the B+ to the BMS
2. Connecting the large connector
3. Connecting the small connector
4. Connecting the charger to the pack

New video by Goncalo Rijo

photos.app.goo.gl

The third light blinks but then it stops and stays forever like that, 0 current drawn and 0 energy into the battery.


Some notes:

• The BMS seems to be in pretty good condition (no physical or water damage).
• I've pressed the battery button for 5 seconds, 10 seconds and even 20 seconds. the result is always the same, it does not charge or discharge.
• I've tested a lot of different combinations on the order how i connect the cables and the result is always the same.
• The cells are all at 3.7V except one set of 4 that was at 3.65V and i've mannually charged it back to 3.7V.
• I've tested it on a purion bike and the purion does not turn on. I've also tested it on an intuvia bike and the display turns on but does not detect the battery, it uses its own internal battery.

Does anyone faced a something similar? Or have any kind of suggestion on how can i further debug the problem?


Thank you

 

[Batteryrepair]

It happens, can be a MCU error. Replace with donor BMS. It's not the can bus nor the 5V DC converter. The Schottky diode is also still ok.

 

[Fric]

Understood. Thank you for your reply!

I've tested continuity on all cables from the box to the connectors on the BMS and they are all working correctly. Also diode is working accordingly on the continuity test. The regulator seems to be also working, i have 5V on the board and it turns on.

One question, do you know if it is possible to reset the MCU?

An when you talk about a donor BMS, do you know where can I get a bms in Europe?
I don't have any spare one, just the battery for the bikes me and my family own.

I was even thinking in something like bad cells that just bump the voltage too much while being charged and the BMS turn it off as a safety measure, but i've tested them extensively and they are all fine.

 

[Fric]

Got a new BMS from a friendly user on this forum, replaced it, and it is working correctly.

Also took the change to recell the pack with new Samsung 33G cells.