Motor has Weak Power

[lexprince]

Greetings,

I have a new 48v, 1000w front wheel GM.    I have a problem.  I installed the eBike kit and after getting it all hooked up the wheel turns with power but will pull me to about 10 miles/hr.  It has very little torque and does not go any faster.  The motor also seems to vibrate a little and or have some intermittent pull (i.e. I would not say it is a smooth pull). I bought a 51.2V, 9Ah, LiFe battery to power the bike.  Everything is hooked up correctly and I took pains to be sure all wiring is correct and connected.  I even took the motor appart to be sure there the wires are properly connected inside the motor.  Any suggestions or ideas will be greatly appreciated.  I want this eBike to work!

David

[alsline]

Hello David, I have the same motor with a 48/20ah battery it tops out @ 59.7v hot off the charger makes 39 mph without load and will do the best part of 30 mph with my lump on it 220lbs. Do you have access to a larger battery for comparison? are you using a cycle analyst? its quite possible a cycle analyst could be set up incorrectly causing your problems,  just a thought. I'm sure there are many on here who can help you, appart from my two penneth I don't know what else to suggest, good luck with it David, Alsline.

[Gregte]

If you are only measuring 51.x volts with a full charge then it sounds like you have a dead cell in the battery.

What kind of battery are you using. I have never heard of LiFe. Do you mean LiFePO4 or Li-Ion or maybe LiFe is something I just have not heard of.

[lexprince]

Gents,  Many thanks for your replies.  I do not have a cycle analyst hooked up.  And yes, I have a LiFePO4 battery that registers exactly 51.2v output on a full charge.  But even if there was a dead cell in the battery would that cause such a major power reduction?  This bike barely takes me out to 10 MPH.  Very disappointing.

David

[lexprince]

Technical Analysis Requested:

I just had the motor described above checked out by an eBike dealer who is very knowledgable.  We didn't have time to open up the motor casing, but he said the noise the motor is making when power is supplied is not good, and the wheel makes an intermittent hesitation when operating, so he said that definitely indicated a mechanical problem in the motor itself.  We also checked out the continuity in the motor harness wires and found no problems. 

If anyone has some insight into what the problem is with this motor that would be very helpful.  Thank you.

David

[Helgeo]

It is possible that one of the magnets inside the motor has come loose. But that would likely cause a more serious problem.
I would try to measure the voltage under load to see what happens.

Will the motor spin faster without load? Like if you lift the wheel from the ground.

[Bikemad]

If there is no noise from the motor when it is spun without power, this could indicate and electrical fault rather than a mechanical one.

It could be a fault with one of the hall sensors, if you have the BAC-282 cruise controller you should hear 2 beeps indicating a problem, and then you would be running it in sensorless control mode.
(I don't know how running in this mode effects the power or smoothness of the motor).

How to work with motor hall-sensor malfunctions:
The controller will detect motor hall-sensor failure and make 2 beeps of sound, and then it automatically
enters into sensorless control mode. Turn the throttle to run the motor. You may need to push/pedal the
ebike or vehicle a bit in case the motor does not move from stall (This is sensorless control limitation, but
happens seldom).

There might also be something helpful in either this post or this one.

It might be a good idea to re-check all the obvious connections again.

I must have checked the connections a hundred times and never noticed the plug from the wheel with five wires from it had one wire that had somehow sliped around to the out side of the plug.

Alan