Ezze sprint suddenly half power.

[MalcolmW]

Hi guys,
After a couple of delightfully trouble free years my Sprint has gone on to half power. Here are the facts.
Battery perfect and charged, green light stays on when on full load. Would normally go to yellow after a short while or heavy load.
If I stall or heavily load the motor and open throttle I still get green but 3 flashes from the diagnostic light. (I have checked that the brake switches are not stopping the motor)
I suspect that the motor is not drawing the full current. The motor rotates smoothly under power.
Can anybody point be to instructions on the next stage of testing? I am electrically knowledgeable enough (not bragging) to do the necessary if I know where to find some instructions.
Grateful for any help
Malcolm White

 

[Deleted member 4366]

It sounds like a throttle problem, or is it doing it with the pedal sensor too. If it's the throttle, it could be that a magnet has fallen out.

Whatever it is, can you check the no-load speed with a cycle computer.

3 blinks means something to to with the battery level gauge, so check any wiring to it.

 

[Cyclezee]

Hi Malcolm,

The diagnostic code does indicate the brake cut off and suggests that you check the wiring and the LED battery gauge. It sounds like you have already done this and probably followed D8veh's advice too.

The most likely culprit is a wiring issue.

You may find the service manual helpful and you can download it from our website here Downloads - electric bikes and conversion kits

 

[MalcolmW]

I have open circuited the brake switches. It also does it with the pedal sensor which I don't normally use.
I will check the throttle, should be easily disassembled, unless you think the fact that the fault is still present using the pedal sensor means its something else. As to no load speed, there is barely enough power to keep it rolling on the flat.

 

[Deleted member 4366]

Unlikely to be the throttle if the PAS has low power too. Is the motor still as smooth as it was before?

 

[MalcolmW]

Unlikely to be the throttle if the PAS has low power too. Is the motor still as smooth as it was before?

The motor is smooth and free-wheels perfectly.
Checked inside battery gauge, no wires off. Cant see how to disassemble throttle but will delay on that one.

 

[MalcolmW]

Thanks to all for the help. I decided to remove the motor wheel and all the electrics for further investigation. I found this very difficult and began to realize that these early Sprints were a bit like a car with the bonnet welded shut; The cabling was routed right from the inside of the wheel, through bosses on the frame to an impossibly inaccessible jungle under the bottom bracket. But you know all this.
Some of the engineering was first rate but the bike could not be considered a proposition; any repairs would not be economic. The plastic used in many parts was as brittle as pitch and the weather proofing was primitive.
I have removed as much weight as possible and intend to retire it to a grandson in Cheltenham which is flat. It will make an excellent pedal cycle shopper.
Thanks for all the help over the few happy years.
ps Anyone want buy a two year old 36v 9ahr LiFe battery. little used and improving all the time?
Over and out