Motor not driving after wet

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zunnyhh   1 µW

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Motor not driving after wet

Post by zunnyhh » Nov 24 2020 4:10pm

Hello everyone,

First of let me apologize as my technical knowledge is very limited, and I dont really know all that much about electrical bikes.
However, a couple of days ago I forgot to place my electrical bike under roofing when it was raining outside and after that I've not been able to get it to run.

The battery was not in the bike whilst it was out, and the display turns on, the buttons to change the power/throttle(?) responds and what I think is called parking assist works when holding the (-) button, so that indicates that the display is atleast able to communicate with the motor.

The issue seems to be that it's not registering that im pedalling. I've so far tried unplugging every connection I've been able to find as well as replace the sensor thats located on the gears, I belive it's called PAS sensor as the light on the sensor was not lighting up.
That didn't change much and the bike is still not registering anything on the speedometer & odometer.

The bike is a couple of years old and what it could read out is that it's a Bafang FM G31 250V DC36V 250W motor.

Any kind soul our there that perhaps could give me some pointers? Also there are no error messages on the display

markz   100 GW

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Re: Motor not driving after wet

Post by markz » Nov 24 2020 5:02pm

Hello, yes I am a kind and caring soul

Is your ebike a diy kit or was is it a store bought ebike whether local store, online store, alibaba store, aliexpress store, Sondors store, mall store, ebay store, guys garage store, basement store.

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Dauntless   100 GW

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Re: Motor not driving after wet

Post by Dauntless » Nov 24 2020 8:56pm

I would want to leave this to real experts, but they're not responding.

Does the shaft still turn? And do you know if it was this hard before? The shaft and bearings can be affected.

Water can break down the insulation of the windings, so you get shorts heavy current draw, etc.

Rainwater is contaminated, made worse by the roof. This could be bad. If you have let the motor dry, that is worse. You might want to flood them in fresh water for awhile. You would need to take the motor apart to clean it. There are ways to test the windings afterward and you need someone knowledgeable to explain that.

From there any connection on the bike is suspect. Hard to say from a distance what's really going on, afterall.

I feel some doubt about you getting that motor going again, but not really something you should take me as the final authority on.
Any sufficiently advanced technology is INDISTINGUISHABLE FROM MAGIC!
- Arthur C. Clarke

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E-HP   10 MW

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Re: Motor not driving after wet

Post by E-HP » Nov 24 2020 9:58pm

zunnyhh wrote:
Nov 24 2020 4:10pm
The battery was not in the bike whilst it was out, and the display turns on, the buttons to change the power/throttle(?) responds and what I think is called parking assist works when holding the (-) button, so that indicates that the display is atleast able to communicate with the motor.

The issue seems to be that it's not registering that im pedalling. I've so far tried unplugging every connection I've been able to find as well as replace the sensor thats located on the gears, I belive it's called PAS sensor as the light on the sensor was not lighting up.
Does your bike have a throttle, or does it only work using the pedal assist? If the "parking assist" function is the same as some controller use as a walk function (3mph or so), and the wheel is turning, then I think you can rule most things out except the PAS sensor. Check the clearance between the disc and the sensor to make sure it's as close as possible.

If you have a throttle, and that's not working either, then I might suspect something with the controller and the 5V circuit, maybe getting wet or fried. Can you provide pics of your PAS sensor, your controller (label) or model numbers?

Welcome to the forum :thumb:

zunnyhh   1 µW

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Re: Motor not driving after wet

Post by zunnyhh » Nov 26 2020 7:30am

Hello everyone and thanks for your replies!

I've done some more testing and the new PAS sensor seems to be working however its acting quite strangely.
Previously before the bike malfunctioned it would assist when slow peddaling.

But after the new sensor was installed it seems to operate in the opposite way, when peddaling fast on low gears it gives 100% power, but when going up to the higher gears and the pedalling goes a bit slower the assistance becomes almost non-existant..

The speedometer/odometer issue seems to be a wire/connector thats not working properly as we were able to get it to work for some amount of time.

Also @E-HP it only has pedal assist.

So current situation: Bike is working but not as expected :lol:

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