BBS02B -Cuts out; screen stays on - no error lights

DerZwen

1 µW
Joined
May 20, 2020
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2
Morning All,

After a year of fairly light (less than 500km thanks to home office cutting down on commuting) use my self build decided to throw up a weird error, tried searching far and wide but couldn't find anything that covered the exact same issue.
Riding a BBS02B 750w with a 52V 17.5ah battery (Samsung 35E Cells) it now started to cut out after about 5-10 mins of use. the screen stays on and the speedometer still shows the current speed but both thumb or PAS are a no show. there is no resistance when rolling backwards and after turning the battery off for a few minutes it will happily again work on both thumb or PAS but will stop working sooner than the original start up. I had it sitting with the wheel lifted up and it would happily spin on thumb without cutting out, so I guess me adding weight and with that extra load is the issue, the motor itself does not get beyond slightly warm to the touch after it cut out. There is no error code or light shown, I checked for water ingress and reseated every connection, both on the cable and from the controller to the motor.
I reached out to the battery seller and they said because the screen is still on all the time the battery is unlikely to be the issue. but I also read that if the controller would be the issue it would not work to begin with, so I am at a bit of a loss here as two where the fault lies, and replacing parts till I find the one bit that might be wrong seems not financially wise.

Any Help is appreciated.
 
Check the battery plug for problems.

Do you have any way to view real time voltage? Here's a meter I've used:
https://www.ebay.com/itm/224285773024

If your battery sag is really bad, you may be triggering the low voltage cutoff in your controller. That seems unlikely for a 52V battery that isn't cutting itself off, but it's a possibility.
 
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