Bafang 750W cuts out every 10 seconds

[daviddlv]

My company rents bikes. We purchased dozens of Bafang 750W over the past 3 years with no issues. Last week we purchased 10 Bufang 750W mid motors from an Amazon vendor. 5 of them work fine. However, on 5 of the others they cut out every 10 seconds. The display stays on, but the motor just stops working. The only way to get it to start working again is to disconnect the battery and reconnect the battery. But the motor only runs 10 seconds. Only error code on display is 21H as we do not have speedometer installed. I hooked up the Bafang programming software and the motors that are cutting out every 10 seconds have identical settings to the ones that are working. The LVC is set to 41volts. I tested with several batteries charged 100% to 53volts.

Any ideas what could be going on with these 5 motors? Could 5 be defective? I'm stumped.

 

[DaLanMan]

I have to say it...

Did you try turning it off and then back on again?

Have you recently patched a microsoft product?

If it is a variable event on just some units, can you swap out controllers etc with one that is not having the issue, that would at least isolate it down to what component is glitching

 

[Papa]

Last week we purchased 10 Bufang 750W mid motors from an Amazon vendor. 5 of them work fine. However, on 5 of the others they cut out every 10 seconds.

Have you contacted the seller to resolve the issue(s)?

bafang error 21H - Google Search

 

[Maciek]

5 out of 10 don't work, sounds like quality control problem. Send them beck where they came from and cancel payment....