Rear hub motor cutting out after stopping

[NOTTNICK]

My wife has a rear hub motor. It has started cutting out after I stop and it sometimes takes quite a long time until the motor kicks in, a particular problem on steep hills.
I have the same setup on my bike (larger wheels).
I have swapped the controller units over and also the batteries but it is still happening.
The wiring look looks OK, I can't see any damage.
The sensor on the bottom bracket that detects the chain ring motion took a knock about a year ago, but I have checked it over and it is running close to the magnetic ring. It is strange though that this is intermittent and only after stopping.
I think the motor is a Bafang, or a Bafang clone.
Our bikes are now getting on a bit but we love them.
My question is: Is this likely to be a motor problem? Or a wiring problem? Has anyone else experienced this?
Any suggestions?
Thanks

 

[saneagle]

My wife has a rear hub motor. It has started cutting out after I stop and it sometimes takes quite a long time until the motor kicks in, a particular problem on steep hills.
I have the same setup on my bike (larger wheels).
I have swapped the controller units over and also the batteries but it is still happening.
The wiring look looks OK, I can't see any damage.
The sensor on the bottom bracket that detects the chain ring motion took a knock about a year ago, but I have checked it over and it is running close to the magnetic ring. It is strange though that this is intermittent and only after stopping.
I think the motor is a Bafang, or a Bafang clone.
Our bikes are now getting on a bit but we love them.
My question is: Is this likely to be a motor problem? Or a wiring problem? Has anyone else experienced this?
Any suggestions?
Thanks

What bikes are they? What control panels do they have? What type of pedal sensors?

 

[NOTTNICK]

 

[thelarkbox]

The static part of the pas sensor looks damaged to me? I have 2 x similar sensors fitted to bikes, both have the sheet steel aspect fitting flush to the plastic sensor housing, In the above pic the sensor housing looks as if its been snagged and pulled off on one side..?

my partial ( and possibly wide of the mark) understanding of pas sensors is the controller picks up on the PATTERN of the pulses produced by the spacing in the ring, so any interruption of that could stop the bike from restarting on que.

 

[NOTTNICK]

Hi thelarkbox. I am sure it is the sensor now. It did get knocked badly several months ago when the chain got tangled up.
It sounds interesting what you say about the pattern though. I shall swap over the dynamic rings just to double check that there isn't a magnet that has dropped out. That is the only part I haven't swapped in trouble shooting.
Assuming it is the sensor, are replacements available? I am sure I won't get the same type (or will I?). If they are fairly generic in how they function, I am sure I could find a way to get something else to fit. I have no idea where to look though - any suggestions as to where to go?

 

[thelarkbox]

ebay or ali-express for the cheapest Chines direct import 1-20 weeks,, tho these days they give honest delivery estimations.. you just have to read them.. 'Pas sensor' is enough to start a search

Some controllers need the pas sensor identifying in the settings usually by magnet count, so getting a like for like replacement generally avoids ay issues there..

pricewise £2-7? if buying from china £15-20 for prompt delivery next day or 2. my similar sensor via yose-power last summer was £15 courier delivered iirc (2-3 days).

be mindful to get the same plug/connector fitting.

 

[saneagle]

That's a terrible design of the sensor arrangement. |It'll get dirt in it, which will wear through the plastic, which is probably what's happened. It might be an idea to replace that with a conventional pedal sensor.

 

[NOTTNICK]

It might be an idea to replace that with a conventional pedal sensor.

That sounds like an excellent plan. Are you able to advise further please. Looking at the design of the cabling etc. It looks like I'll need to cut the current wiring on the Bottom Bracket and add a connector anyway.

 

[thelarkbox]

The sensor OP currently has is just secured behind the bottom bracket retaining ring, and can be orientated in any location, not just the underside of the bike. and is a bit of an extra pita to fit.

If opting for an alternative style, check the crank/axle diameter before committing to the all in one left side sensors as if your bikes crank is Over 17mm in diameter the all in one sensor can foul, rotating with the crank until halted by cable tension pulling on the lead and delaying both pas start and stops by a varying length of time. - why i had to switch to the same style as OP is having problems with..

If OP's bike crank is engineered to better tolerances than mine and is 17mm or a tad less, Then the all in one and cheapest pas sensor option is a viable option, and while the crank size issue is probably not relevant here? if it goes unsaid??

 

[NOTTNICK]

All advice appreciated. I have ordered a simple PAS kit on Ebay for £7. I think the sensor might just swap over although I will need to rig up some solid / waterproof cable connector under the Bottom Bracket as there is no way I can get access to anything like a controller unit. I'll see what happens. Thanks