Bafang BBS01b low power with low cutoff cadence

marshall2389

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I've had this motor for 2.5 years and it's worked very well. In the last few days it has been acting funny. Half the time I turn it on I get no assist. The display reads full battery voltage, but no assist. The other half of the times the assist will kick in. However, it's only providing about half the power it normally does. My display doesn't show motor current or power, but the 3 amp setting is unnoticeable and the 15 amp setting feels more like 6 amps.

Any ideas?

The battery connector looks fine. I would think if it was a connector issue then the voltage seen by the display would go way down when lots of current is being drawn by the controller. However, the voltage on the display doesn't change when the motor is powered.
 

Capt Kirk

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Just really curious, but is it the original battery? Can you get a voltage reading off the battery with an external volt meter? And does it have a throttle and how does the motor respond when using it?
 

marshall2389

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It is one of two batteries I had made. Each are 36V-21Ah Panasonic 18650 cells in a Sea Lion (I think) case. I can't get the battery voltage with a voltmeter while using the system. However, the C961 display shows the battery voltage in 5 increments. The motor has been acting funny while the battery voltage has been at 3-5 out of 5 bars. The voltage hasn't dropped unusually for the loads.

No throttle.
 

Capt Kirk

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You are saying there is no throttle right? How many hours approximately does the motor have on it? Does it generate any noise? Is it possible that the motor gear drive train needs to be regreased? Sorry for all the questions, but I am trying to get a picture of your problem, and trouble shooting requires tthe elimination of everything that works right to get to a solution. The one possible solution is to pull the controller out of the motor, and install a new one, I do not like to "shotgun" a repair, but swapping known good parts helps eliminate possible problems. Anyone else out there have a similar issue??
 

marshall2389

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Yes, no throttle.
Probably 7 hours at 15 amps (the maximum setting I have programmed. The controller says it's a 20 amp controller). Only at less than 65 rpm cadence briefly while accelerating from stops. The rest of the time I ride between 80-95 rpm (155 mm cranks).
Around 800 hours at 3 amps. Again, only below 65 rpm accelerating in my lowest gear from a stop. The rest of the time between 80-95 rpm.
No unusual noise. I will be opening up the motor when some parts come. I'm swapping out the rotor/stator to get a higher no-load rpm.
When I open it up I will test the MOSFETs with my multimeter and regrease all gears (with Mobilgrease 28, apparently safe for nylon gears).
I think it may be the display. I used an Android phone with a Bafang app as the display and my kit worked normally. Since replugging in my display, the kit has acted funny or not at all three out of the last 7 rides.
 

Hoggdoc

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Yes, no throttle.
Probably 7 hours at 15 amps (the maximum setting I have programmed. The controller says it's a 20 amp controller). Only at less than 65 rpm cadence briefly while accelerating from stops. The rest of the time I ride between 80-95 rpm (155 mm cranks).
Around 800 hours at 3 amps. Again, only below 65 rpm accelerating in my lowest gear from a stop. The rest of the time between 80-95 rpm.
No unusual noise. I will be opening up the motor when some parts come. I'm swapping out the rotor/stator to get a higher no-load rpm.
When I open it up I will test the MOSFETs with my multimeter and regrease all gears (with Mobilgrease 28, apparently safe for nylon gears).
I think it may be the display. I used an Android phone with a Bafang app as the display and my kit worked normally. Since replugging in my display, the kit has acted funny or not at all three out of the last 7 rides.
I would give a call to Luna cycles in Southern California and run this past them they may have an idea they are real big in your type of motor system.
 

Nelson37

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So, you replaced the display, it worked fine, put the original display back on, and it malfunctioned as before, and YOU THINK IT MAY BE THE DISPLAY???????

It IS the display. R & R one more time for absolute certainty, but it's the display.
 

marshall2389

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Turns out it was the battery connector. The connection between the high wire and the pin inside the Anderson connector was just loose enough to cause the aforementioned systems. This became obvious when, after hitting a good bump, the assist system and electric lighting/indicating system went down. The 12 volt converter for the lighting system connects right after the battery connection. So, since they both went down, it meant the battery connection or the battery itself (maybe BMS) were the source. I re-did the Anderson connector and it's been all good since.
 

Nelson37

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My mistake, I glossed over the critical piece of information in the last post. "three out of 7". Less than 50% of the time. Intermittent problems are almost always a loose connection or broken wire somewhere. Original posts indicated the problem was constant, as in EVERY TIME.

I did say to repeat the Remove and Replace a second time to be sure, however I failed to read carefully.
 

BBassett

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It's nice to have spare components when trying to troubleshoot something. I bought a backup BBSHD, two spare controllers, gaskets, and backups for most of the internal parts. The 1st thing I do is reinforce the wiring harness and tailor it to my bike using adhesive-lined heat shrink tubing, both backup controllers are ready to go to replace or for test purposes. I am going to tempt fate here and say that once you have a quality install with quality components the BBSXX series is seriously reliable. I've used 2 motors and have ridden over 37K miles. Stay safe.
 

marshall2389

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It's nice to have spare components when trying to troubleshoot something. I bought a backup BBSHD, two spare controllers, gaskets, and backups for most of the internal parts. The 1st thing I do is reinforce the wiring harness and tailor it to my bike using adhesive-lined heat shrink tubing, both backup controllers are ready to go to replace or for test purposes. I am going to tempt fate here and say that once you have a quality install with quality components the BBSXX series is seriously reliable. I've used 2 motors and have ridden over 37K miles. Stay safe.
Yep, my issues have always been my poor connectorizing skills.
 
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