Help! Where's my power gone?!

[Peter Mc]

Hi, I hope someone can help or maybe point me in the right direction ...

I've got a Raleigh Velo Trail, which has a 42v system with a generic front hub motor and a TMM torque sensor.

Since it came out of winter storage, it's just not producing any power. If I load up the torque sensor (with the front wheel off the ground), the wheel rotates, but taking maybe 20 seconds to complete one revolution. Even then, it turns very roughly, as if the supply to it is pulsed maybe two or three times per second. Crucially though, it does rotate through 360°, potentially exonerating the motor hall sensors and the controller MOSFETs.

Rightly or wrongly, I briefly shorted the signal wire on the torque sensor to its own +ve feed as a means to bypass it. The wheel turned a little faster than when loading up the torque sensor, but still very slowly and very roughly.

I've no reason to suspect the battery (it charges normally and holds voltage indefinitely), and I've forensically examined the controller internally and externally, and all of the wiring, plugs and connectors.

Any help would be gratefully received.

 

[vfr400]

You get that when the controller is not firing a sychronising the power pulses correctly. There are a number of possible causes, but using logic, if it was working OK when you put it away, some are more likely than others, so, I'll put them in the sequece of likeliness bearing that in mind:
1. Motor phase wire connection bad (motor connectors)
2. Hall wire connection bad (motor connectors)
3. Motor cable damaged.
4. Hall sensor blown or faulty.
5. Mosfet in controller blown.

Whatever you do, don't attempt to run the motor for any length of time when it's doing that otherwise you end up with blown mosfets. Often, people get a faulty connection, which causes the bad running, then they try and clear it by running the motor, but running like that causes massive currents that the controller can't cope with.

If after doing a visual check of those things, it still hass the problem, you'll have to do an electrical check that the halls are switching and mosfets not blown.

 

[Peter Mc]

Hi @vfr400, many thanks for your fast response and good guidance.

I think I can eliminate causes 1 and 3 above, as I've conducted continuity tests and visual inspections, but it sounds as if I've been naïve in assuming that the Hall sensors and MOSFETs could be sound given the symptoms. I'll run tests on each of them and report back.

Many thanks once again.

Best regards

Peter