Assistance cuts out (different problem)

[Black Dog]

This is not related to williec79's issue (at least I doubt it) -

http://www.pedelecs.co.uk/forum/threads/problem-assistance-cuts-out-intermittently.21703/

- but reading that thread prompted me to post this query. Occasionally, the electric assistance cuts out for a moment, and then resumes almost immediately. This always happens when climbing a very steep hill at perhaps 4-6 mph, and the 'miss' in the assistance is enough to cause a bit of grief, as the bike slows down almost to a halt and it's an effort to get it going again. The obvious cause would be a momentary pause in pedalling due to the strenuous nature of the climb, but I am sure it isn't that for two reasons - 1) I have observed the problem with this in mind and I am certain that my pedalling is smooth and consistent, and 2) when I stop pedalling under normal circumstances, the motor continues to assist for 1-2 seconds after I stop, whereas this break in the power is instant, and probably only half a second. But it interrupts the ride and it's annoying. It only happens on steep hills in the lowest gear when I am pedalling hard (cadence 80-90 or so). My hands are nowhere near the brake levers, so I am sure it isn't that that cuts the power.

Bike is a Wisper 905 Classic with Dapu rear hub motor. It's not a massive issue, as it only happens less than once per journey (say once every 25 miles approx.), but the bike is less than a year old and under warranty, and I am taking it back for a service soon, so it would be good to know if something was wrong so I could get it fixed. Many thanks for any opinions or advice.

 

[KTM Bike Industries UK]

Why don't you ask Wisper?

 

[Deleted member 4366]

In those conditions, the current will be at its maximum. It could be a bad connection anywhere on the main power lines from the battery cells to he motor. It cold be over-current protection or under-voltage tripping. What do he battery LEDs show at the point of cutting out? Does it do it at all states of charge of hr battery?

 

[Black Dog]

Why don't you ask Wisper?

I will, if necessary, but I thought I would ask here first, in case there is a reply like "yes, they all do that, you need to do xyz", and I can sort it simply. It's going back to the supplying dealer for a service soon, and if they can't fix it I will contact the manufacturer. Thanks for the advice.

Also: if we all went straight to the manufacturer with any queries, there wouldn't be much of a forum here

 

[Black Dog]

In those conditions, the current will be at its maximum. It could be a bad connection anywhere on the main power lines from the battery cells to he motor. It cold be over-current protection or under-voltage tripping. What do he battery LEDs show at the point of cutting out? Does it do it at all states of charge of hr battery?

Yes, it's only when the motor is working very hard at low speed that it happens. Bottom gear, steep hill, maximum effort from the pair of us. All battery states, although the battery rarely gets below half as I charge it every round trip (27 miles). I haven't looked at the battery LEDs when it is happening, as it's momentary, and the LEDs are hard to see anyway unless it's dark. I would think under-voltage was unlikely, but over-current possible.

However, you've made me think. It hasn't happened recently, and ... I have been going out on my push-bike at weekends for the last month, trying to get fitter so I can use the touring bike for work instead. I have noticed a huge improvement in my leg strength and endurance - so much so that six hills that I used to ascend with difficulty in bottom gear when I started riding it (and where the cut-outs happened) I am now getting up in the third-lowest gear, faster, and with a lot less strain. Also, now I think about it, there was a horrible grating whine from the motor when I was climbing the steepest parts at about 4 mph, which felt like I was asking too much of the bike. I haven't heard that noise recently. The lack of noise, the lack of cutting-out, and the push-bike training have all happened at around the same time. And the bike is running (or seems to) faster and quieter than ever. Perhaps it's not a case of the bike getting better, but the rider getting fitter. The idea of the controller protecting the bike from over-current makes perfect sense. I think I'll call that 'solved' until it happens again.

Many thanks for your input.

 

[Wisper Bikes]

Hi Black Dog, and thanks for your help Dave.

It does sound like the thermal cut out may be trying to trigger, this happens when the motor gets too hot and protects the motor from Damage.

If you have any further difficulties please give us a call or email me directly.

All the best and happy cycling.

David

 

[Black Dog]

Thank you for the response, David. I'm fairly sure in my mind that this is the answer. As long as I stay fit (ish) it shouldn't happen again, I hope. I will contact you if I have any concerns.

 

[Wisper Bikes]

Thanks Black Dog, enjoy the weather!