I have an ebike with a 1500 W mid-drive Bafang motor and controller. The assist mode will frequently cut out and the only way I can get it running again is to repeatedly pump the thumb throttle button. But even then, it doesn't last for long and I have to do it again. The bike isa Velotrix and is about 4 years old with only about 100 miles on it, so it's out of warranty. Has anyone else had this problem with the Bafang mid-drive?
Intermittent problem
- Thread starter Artie
- Start date
slitespd
Member
- Region
- USA
Does the bike have brake lever motor cut off? If so, could a brake lever be sticking a bit and the aggressive throttle closes the contact again?
Gionnirocket
Well-Known Unidentified Member
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- Y. O.
25 miles a year... Man you're tearing it up! 
As stated I'd check the brake cut outs. They're not necessary for the bike to work so you can try unplugging them near the levers.
Also check the speed sensor magnet
Then I'd go over all the connectors... intermittent many times means a loose/poor connection. Maybe one is fouled with a little oxidation and you can use some contact cleaner
Do you get any errors on the display?
As stated I'd check the brake cut outs. They're not necessary for the bike to work so you can try unplugging them near the levers.
Also check the speed sensor magnet
Then I'd go over all the connectors... intermittent many times means a loose/poor connection. Maybe one is fouled with a little oxidation and you can use some contact cleaner
Do you get any errors on the display?
Chargeride
Well-Known Member
Are you pumping the throttle with no response from the drive?
PCeBiker
No-Hands No-Pedaling No-Credentials
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- Canada
I'm thinking perhaps a bad cadence sensor?
If your ebike responds to the throttle (perhaps without the pumping) then it may be a slipping or binding cadence sensor?
Does everything work properly when just using the throttle?
(There's a time delay for throttle response)
You might just have a slipping/binding/dirty cadence sensor?
As far as I understand it, the throttle overrides the cadence sensor, But the throttle has a computerized time delay.
(I hate computer control)
Try holding the throttle full and see what happens.
If your ebike runs normally under throttle control (keeping the time delay in mind) then it's probably a bad cadence sensor or it's connection.
If your ebike responds to the throttle (perhaps without the pumping) then it may be a slipping or binding cadence sensor?
Does everything work properly when just using the throttle?
(There's a time delay for throttle response)
You might just have a slipping/binding/dirty cadence sensor?
As far as I understand it, the throttle overrides the cadence sensor, But the throttle has a computerized time delay.
(I hate computer control)
Try holding the throttle full and see what happens.
If your ebike runs normally under throttle control (keeping the time delay in mind) then it's probably a bad cadence sensor or it's connection.
PCeBiker
No-Hands No-Pedaling No-Credentials
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- Canada
25 miles a year... Man you're tearing it up!
I felt bad about procrastinating until summer to go for my first ride.
I put 200 km on my ebike in the last week.
Gionnirocket
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PCeBiker
No-Hands No-Pedaling No-Credentials
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EDIT:
Mid-drive Bafangs don't have cadence sensors. (as far as I know?)
But I'm pretty sure that there's a sensor in a mid-drive motor to check for pedal/crank rotation?
I had my Bafang mid-drive running with no speed sensor installed.
But it seemed to know when I was pedaling, and kept PAS activated?
I'm only interested in using my throttle, so I shut the PAS off.
The throttle always worked when I didn't pedal.
Using PAS, if I stopped pedaling, the power would cut out.
Chargeride
Well-Known Member
Lets get back to basics, is this an Ultra bafang mid drive?
PCeBiker
No-Hands No-Pedaling No-Credentials
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- Canada
For reference, my mid-drive is a 750 Watt BBS02B, but I'm 99% sure that every Bafang mid-drive has some sort of crank sensor that enables PAS.
So if the controller thinks that your not pedaling, it will turn off the power.
Gionnirocket
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I doubt it
I believe if anything it's 500w.
I doubt it's a BBS* version of a Bafang
If on a Velotric it's probably one of the OEM motors which means the axle incorporates both the torque and cadence sensors.
Anything is possible but a 4 year old bike that's been pretty much sitting... We need more info and I'd start with the simple and more common issues.
I also think his throttle input temporarily fixing things is probably coincidental.
I'd also take a look at the battery and make sure it's fully charged and working correctly. It may not have been stored correctly
PCeBiker
No-Hands No-Pedaling No-Credentials
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- Canada
Plus they would be better protected inside the motor housing, so a loose/poor connection would be less likely.
The cadence sensor for my hub motor is prone to getting clogged with dirt, and wearing out.
It's also externally wired, so a loose/poor connection is more probable.
stompandgo
Well-Known Member
- Region
- USA
I swear there was a brand called Velotrix that doesn't exist anymore. I could be full of it, though.
Gionnirocket
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PedalUma
Well-Known Member
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- Petaluma, CA
Most factory hydoro levers have an 8mm adjustment screw at the electrical signal input. It could be as easy as one-quarter turn out. I am trying to not show off in front of a customer and fix their bike in 7 seconds. Go have lunch and come back is better.
Gionnirocket
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He should have an indication on the display if that's the problem... but I'm guessing he'll be back in 4 years
PedalUma
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- Petaluma, CA
When the customer has spent two weeks on a problem and you fix it in seven seconds right in front of them it just makes them angry and they do not want to pay. But if you do exactly the same thing while they are gone for 45 minutes having a burger and shake, then you are a genius and so fast. They will not only pay, but also give a tip, and a five-star review.
Chargeride
Well-Known Member
No worries mate, get yourself a burger and it will be fixed when you get back.
PedalUma
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- USA
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- Petaluma, CA
I have had people come in with a non-working throttle. You can see the red or yellow of the connector. And it is so hard not to to just plug it in all the way on the spot. At times it is just hanging there, totally open, and they can't figure out what could be wrong. Then there was one lady who saw a video on tightening brakes, so she pulled out the barrel adjuster a few turns at her caliper and fluid came out.
