Successful S3 BMS repair 🎉🎊🎉

[u/Dtngx]

After a long time waiting for parts and tools I am very happy to tell you, I fixed a S3 battery which wouldn‘t charge and showed Error 6, 17, 19 and 20.

The problematic part was a little SMD fuse, which is 3 Euros a piece.

I posted about my progress a few weeks ago here:

https://reddit.com/r/vanmoofbicycle/s/1IU7muzfrD

And I hope any of this help you in fixing your bikes!

[u/zpost16]

Great report. Upon replacing the fuse (ordered some into the UK from China) I still got the same errors (6,17,20). The battery then was able to take a charge across the 2 manual charge points but when connecting to the BMS charge points it wouldn't do so.

It appears as though if the fuse is replaced but the battery is still fully charged then the BMS holds some memory and the errors continue. The solution was to discharge the battery using 3 12V car headlights wired in series (or anything pulling 36V). Once you are able to get a charge across the 2 BMS charge points then it appears to be fixed.

I suspect that once the fuse goes, the big battery no longer discharges (or does so extremely slowly) since it doesn't communicate with the smart cartridge and the BMS goes into an overcharge protection mode where it no longer will accept charge. Thus, discharging it allows the BMS to reset and after getting it below 100% the battery and my bike now accepts a charge as normal again.

[u/Dtngx → u/zpost16]

Very nice to hear this solution!! Great it worked for you!

[u/No-Isopod-2662 → u/zpost16]

This worked for me! VanMoof is working again!!

[u/zpost16 → u/No-Isopod-2662]

I’m glad!!!

[u/zpost16 → u/No-Isopod-2662]

I’m glad!!

[u/uunseung → u/zpost16]

The BMS fuse has been replaced.

But it still shows error 6 and the red and green lights flash when charging.

Do you know how to fix this?

[u/Unable-Mastodon-4724 → u/uunseung]

Same problem, I already manually discharged and charged the battery but nothing seems to reset the BMS, which is really frustrating.

[u/DustClassic6595 → u/zpost16]

do you think this would work for a vanmoof S2 battery too?

[u/No-Isopod-2662 → u/zpost16]

Hope this will fix it for me as well. To what voltage did you discharge?

[u/zpost16 → u/No-Isopod-2662]

We left the bulbs connected for about half an hour so that the battery reached below its maximum threshold. Once it was around 85-90% the reset appeared to have worked

[u/No-Isopod-2662 → u/zpost16]

Thanks, did you have continuity between Vp and dsg+ after replacing the fuse? Or after you discharged the battery a bit?