MP3 failure - throttle gauge flashes twice then motor doesn't work

[REV Bikes]

Hello Brains trust,
We have a customer with a new MP3 (20") that is being installed in a velomobile to be entered into a 24hr electric bike race by Holmesglen TAFE(technical college).
They have a motor that after installation (2nd time installed as the first wheel we gave them was terribly out of balance) would not work.
They plugged it in then switched it on.  The throttle battery gauge flashed twice then the lights went out and the motor would not work.
I'm going to see them today but would like some help problem solving their issue.
Can anybody help?

[Bikemad]

Hi Rebecca, I expect this reply may be too late to help you now, but I'll post it anyway just in case.

First of all, check that the measured battery voltage is above 36V and below the acceptable maximum of 60V.

There are several things that could cause this problem, these include a faulty throttle, a faulty power switch contact or a poor connection somewhere between the battery and the controller.

If you are able take your bike and battery with you, it might be easier to diagnose the problem by trial and error by substituting certain components, or even by plugging your main harness into the motor to see if the problem is on the motor harness, main harness or somewhere on the battery supply circuit.

Alternatively, if you have a spare motor kit, or main wiring harness and throttle control (preferably one that you has been tested) you can simply plug it into the motor harness and see if the throttle and battery gauge lights work properly:

• If everything works, reconnect the old harness and substitute the old throttle with the new one. If it works, the old throttle has failed. If it doesn't work, try connecting the new harness with the old throttle to see if the fault is in the main harness itself.
   
  
• If the new harness and throttle make no difference, then you will need to check for the expected battery voltage at the battery plug connection. If the voltage is correct, but the battery gauge lights still don't work then I would then say that a poor connection within the motor harness could be causing the problem.

Please let us know what you find.

Alan

P.S. Check out this post for another simple test that you might want to try.

[Jemen]

Hi R!
I got almost the same trouble yesterday. With no load on motor battery gauge lights fine.
Try to give a little power and all stop. In my case it was battery switch.
Battery switch was bad built so it was burned out. I soldered it away and put it in pieces.
Bottom part in switch was not proper insert so it result in bad connection between moving plate and bottom plate.
Se pictures.
Jemen out and ....

[REV Bikes]

Thanks for your help on this one guys.
We ended up replacing the controller, which was a great learning experience for the students.  Gave up on trying to work out exactly what the problem was.
Hope your biking well