Hi, I'm from France, so please excuse my bad english...
I've got a regen 36V500W and it is working great.
A neighbor of me bought a 36V250W motot kit with batteries.
And the same happened:
Worked great a few km, but then make noise and cut offs, like bad battery, then doesn't worked anymore.
We have tested every of his component on my system and mixed things to be sure to test everything out.
Result: a bad twist and a defect controller!
I don't find the relation between the twist and the controller...
BTW on his battery when fully charged, there is still an illuminated led, that stays always on even after a very long charge...Dead Cell?