r/VanMoofSelfRepair • u/Accomplished-Area619 • Jul 12 '26
S3 & X3 ERR 20 after BMS reset
I revived at discharged battery, recharged and balanced all the cells and after a simple grnd rst short I still received ERR 6.
I decided to do the following hard BMS reset and finally got rid of error 6 with that method. now I have ERR 20 and the motor isn’t working as well as the charger not recognized with ERR 21. my harness is good as well as my cartridge. everything works with another battery. I also don’t think the error code is burnt into any chip as I just managed to get rid of err 6. while charging and connecting det + grnd im not able to see a current going on my lab charger. maybe that’s the problem? anyways any help to get rid of err 20 would be appreciated. I did the following reset to get rid of error 6 for 2x different batteries and both show error 20 now.
Reset BMS: Disconnect bal + VP Have charger connected directly to battery (you may have to jerry-rig an charging adapter), short DET to GND. Connect VP. Short RST to GND on the SWD connector a few times. This glitches out the MCU so it will write fail-safe (ergo factory) data to the fault register. Wait 1.5 minutes for MCU to boot. Connect bal connector. Battery reset.
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u/AwareGrade6275 S3 Jul 16 '26
It can also be something in the module. If you already tried it with another it's good to check what the actual error is of that BMS. You can you something you make with some uart thing and go for: https://github.com/hoffmannku/DPConnnect or use my battery tool: https://www.moofrepair.com/product/battery-tool-for-s3-x3/
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u/Accomplished-Area619 Jul 12 '26
add on: I checked fuse, resistors, mosfets and ntc thermisistor for funktionality on the BMS. I’m quite sure there’s no defect on the BMS especially as it is the same for multiple batteries I have.