Help! Intermittent power on GSM mid drive

[EmSeeDee]

Hi, all,

I’ve been happily using a GSM 250W mid drive kit on my hub geared utility bike for the past 5+ years, but this morning it started to play up. It’s fine for 20 seconds or so, and then the assistance cuts out for 2 or 3 seconds before returning to normal and then the good/bad cycle repeats. There is nothing unusual on the display, I wasn’t going anywhere near the max speed and the battery seems healthy.

Where would I start looking for a fault? (I’m fairly confident/competent with things mechanical and electronic).

thanks

Mike

 

[Nealh]

The GSM had many a fault with heating issues so either controller or likely the windings got to hot and some thermal cutout/loss of performance, I suspect the issues are pretty much like the tsdz2 issues with heat.
I had two GSM 5 years ago and both were crap reliability wise though good like most things when they worked, #1 managed 250 miles before failure & #2 lasted way less then that. One reason why they eventually stooped producing them and Woosh stopped supplying them.

 

[Nealh]

Hold your hand on the motor next time it cuts out and see if it is warm tot he touch.
You have done very well for 5 year usage.

 

[EmSeeDee]

I did 15 miles on it a few days ago, in quite hilly terrain, so I suppose it’s possible that I’ve cooked the controller. Certainly didn’t get hot this morning - I only did a few hundred metres before I noticed the problem. Is it likely to be the controller, or the motor windings? If the controller, would an external replacement work, or am I really looking at a new complete kit. I’m assuming that gsm parts aren’t available.

 

[Nealh]

The power loss might be cooked windings, cooking demagnetises them thus the power reduction/loss. One would need to open the motor to check if the cooper windings are burnt.

My two were heat issues both motors got very warm and one reason why they stopped making them.
Woosh might be able to help ?

 

[Nealh]

Anotherkiwi who is a member but no longer posts as he is now on a German velo forum, he used a KT ext controller and PAS on his GSM after it failed. So it may be a controller fault, I suspect it is more then likely a mosfets issue with heat.

 

[EmSeeDee]

Anotherkiwi who is a member but no longer posts as he is now on a German velo forum, he used a KT ext controller and PAS on his GSM after it failed. So it may be a controller fault, I suspect it is more then likely a mosfets issue with heat.

That's helpful. I had a look inside the motor unit today, and there's no obviously sign of anything overheating, although most of the electronics are potted up so I can't get a good look. It's quite clear that there's no way of replacing the internal controller with a similar unit because of all the potting compound, and there are some signs of wear on the nylon gear, so perhaps it's time to call it a day with this motor rather than throw good money after bad.

For the time being I've converted the bike back to its original (non-powered) condition, and I'll just have to use my converted Brompton if I want to ride electric. I'm going to be off the road for most of the next 6 months (2 new knees) so I'll probably wait until the autumn to decide on next steps.

Mike