Loss of power on new black pie vector 20 inch front wheel

[Crancurt]

When I first connected my 48volt battery, throttle and accessories to the black pie 5 front wheel I picked up the wheel off the ground and pressed down the throttle. With no load on the wheel spinning in the air the speed on my speedometer read 50.6kph.  After a short test ride up and down the block and turning it on and off when I lifted the wheel up it said the same speed.   The next day before taking it out for its first real ride I lifted the wheel of the ground and the speedometer only read 28-29kph when spinning with no resistance and no longer had the same speed or acceleration that it did the first day by a significant loss

[Bikemad]

Hi Crancurt andto the forum.

If you haven't changed any of the controller settings using Bluetooth or USB, it could be a problem with either the +5V supply to the throttle or the throttle itself.

I suggest that you first check the voltage of the +5V supply from the controller, which you should be able to do by placing a voltmeter across the Red and Black wires on the pedelec connector (or the unterminated wires on the motor harness if pedelec connector is not fitted).

It should be around 4.5~5V, but if your voltmeter is showing less than 3.5~4V try unplugging the motor harness from the main harness and measuring it again.  If you have the Bluetooth dongle plugged in, try unplugging it to see if it makes any difference to the +5V supply.

If the +5V supply is below 4V with the Bluetooth dongle and main harness disconnected, I suspect that it might be a poor +5V voltage regulator in the motor controller. If this is the case, the controller will probably need to be replaced. 

Alan
 

[Crancurt]

Hey, Thank you for your response.

I haven't changed any of the settings. I got a brand new multimeter and tested the wires you mentioned. The first test with everything connected read 3.1 volts.  I unplugged the motor harness and It read 5.0 volts.  I plugged the harness back in and unplugged the throttle and it read 5.0. volts. With the throttle plugged back in it read 3.1 again. Does this mean the throttle is the issue?

[Bikemad]

3.1V is definitely too low, The throttle signal output needs to be 3.25V or above in order to produce full throttle. If you only have 3.1V going into the throttle, the output from the throttle is likely to be even lower.
This would definitely explain the decrease in speed and acceleration that you have experienced.

It will hopefully just be a faulty Hall Sensor in the throttle that is overloading the controller's +5V supply, but you won't know for sure until you actually replace it. Make sure that you get a 48V replacement  throttle to match your battery, as the 24V and 36V throttles will get very hot on a 48V pack.



But, if the fault is still present with a replacement throttle, I would then say it is being caused by a weak +5V regulator, which is an integral part of the controller. 

Alan
 

[Tommycat]

Just happen to have a chart that illustrates this...   





The throttle's hall sensor integrated chip on average will drop the output voltage @ wide open throttle by about .6 volts DC over a range of lower than normal input voltages.

Perhaps another check for a shorted Hall sensor would be to check it's current draw. It should be typically less than 7 milli-amps.

For more detailed information on operation and troubleshooting see...  Guide to Hall Sensor Throttle operation, testing, and modification.


Regards,
T.C.