soon turned into a failure, due I assumed to a faulty cell or group causing excessive voltage sag under load and the BMS cut out even though the off load voltage was around 35V or more.
TL:DR - very happy with Yosepower's service
Longer Version
The battery was 9 months old and Yosepower sold it with an 18 month warranty so I emailed them with a reasonably full account of the problem.
I have to admit not with any great expectation of success, but was pleased to receive an overnight reply from Winona (!). She asked me to repeat the charge/discharge cycle which I did and the following day she authorised a repair at their facility in Germany (one Albert Fischer).
That caused a slight problem in that no courier seemed willing to accept a lithium battery at anything like a reasonable cost so I emailed Albert who suggested leaving it the rear rack with the controller and wiring and declare it as Li battery contained in equipment (which it sort of was) as that apparently has a lower hazard category. This turned out to be true and UPS were happy to deliver it to Germany for £20.
Slight delay for the Xmas break but Yose emailed me saying the battery could not be repaired and that they will refund me in full for the original purchase price, as they no longer supply that particular unit. I was quite satisfied with that as I always had suspicions about that battery - it was fitted to my wife's MTB - it never seemed to last as long as my own Yosepower battery (in the Hailong package) which continues to perform faultlessly.
The replacement arrived today (same HL packase as mine which is convenient) and she now has a working e-bike again, so a thumbs up from me.
OK it failed but things occasionally do, what matters to me is how the supplier deals with it.
If a Li battery doesn't explode underneath me I count that as a win personally
Would like to read about other's experiences
