Bike occasionally cutting out

[andyc]

I have a 3e mountain bike that I use for urban cycling several times a week, up to 7 miles at a time (often less), sometimes with heavy panniers, sometimes up steep hills. Have had it 2.5 years, got it second hand, little used and battery well looked after (from what I could tell). It has been great to ride (much better than my previous Ezee Torq which was stolen). Recently it has failed to assist when I start off on a ride but after 5-10 secs does assist and then cuts out very shortly after, then soon kicks in again and is usually OK for the rest of my ride, but is sometimes slow to assist from stationary. The last time I used it, it also cut out completely when I was riding it - this seemed to be when going up a steep hill, it did then eventually kick in again.

Any suggestions as to what I might do to rectify it?

 

[Nealh]

Voltage when fully charged ?
Approx range from a full charge ?
Battery type ?
Cutting out on hills is a classic battery voltage sagging under load which suggests some cells may be out of balance/loosing capacity, the age of the battery could be an indicator to this problem.

Other likely candidates are if on flat ground are the pedal assist sensor/magnet position located under the bottom bracket, should be 1-2mm gap and sensitivity of brake sensor if fitted.

 

[Deleted member 4366]

The key switch is a prime candidate. Check the solder joints on the back of it. It's probably a good idea to resolder them anyway with plenty of heat and time to make sure it's properly fused.

 

[andyc]

Thanks guys.
Voltage when fully charges 42.7v. Ben Yuan Battery 37v/18AH Not sure of range as I try to keep it topped up.
Yesterday I noticed that it seemed better on the high setting (I usually try to use it on low or medium to get more exercise) - it went up a reasonably steep hill fine when on the high setting! Today I cleaned what I think is the sensor (against the large front chain cog), also cleaned the wheel inside the cog that is aligned to the sensor. Went out this evening, but only for a short run and it seemed much better, so fingers crossed it may have rectified it.

The key lock is in the battery - I had got the impression that going inside the battery should only be done by someone who knows what they are doing....True?