My Magic Pie stops under load

[keratea]

Hi to everyone.
I am a happy Magic Pie rider for about 1 1/2 years.
I have down already about 2000 Km and the only problems was the internal controller, but
when I changed it with an external one the problem solved.

A week ago I was riding my bike in a heavy raining day and the motor did some stops for
a few seconds and I did not took any other attention.
From that day and after when I push hard the throttle the motor stops.
When I turn off and then on the battery key it starts again, but I am riding with not full throttle.
I did another test. I pushed the throttle slowly from minimum to maximum when I was not on the bike, I felt the power of the motor more and more, but when the power was about 70% the motor started to make cut offs repeatedly, and was doing like a street hummer.
After a few seconds the motor suddenly stopped. Then I had again to turn off and on the key battery.
Please let me know if someone had same problem where must I look first?
Is it an electrical problem? The hall sensor?The throttle?
Finally when I put the wheel on a stand it accelerates o.k. and seems not problem.Only
under load had the problem and remember it happened after a raining day out there...

Thank you http://goldenmotor.com/SMF/Smileys/default/smiley.gif


 

[Bikemad]

Unfortunately, it sounds like your cutting out problem is being caused by the battery, not the controller.

Do the LEDs on the throttle control go out completely when the motor cuts? if so it could be a poor connection on the battery plug, or possibly a faulty group of cells within the battery.

Your 36V battery consists of 10 groups of cells which are individually monitored by the battery management system (BMS).  If the voltage across any of the groups of cells falls below a predetermined level, the BMS will automatically disconnect power to prevent the cell voltage from going too low and causing permanent damage.  Normally, this would only happen when the battery was almost completely discharged. But if one of more groups of cells has become faulty, this could easily cause the voltage to fall too low on the faulty group/s of cells when the motor was under load, even with a fully charged battery.

As you've mentioned that this problem only started after being used in heavy rain, I'm wondering whether water may have got inside the battery and somehow affected the BMS circuit board, producing a similar effect, or perhaps the water might have somehow affected the cells themselves.

In order to try and confirm the cause of the problem you would need to check the voltage across each of the cell groups while the battery was under load, to see if one group was reading significantly lower than the others, but that's not going to be an easy thing to check.

Alan