BBS02B intermittently applying power during ride - HELP!!!

bpmessenger

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Jun 9, 2022
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Hi all. Hopefully someone can help me here (apologies in advance for the long post but will try to give as much detail as possible)

I have a BBS02B 750W which was fine for the past few months (bought maybe a year ago, max). Recently, when hitting the throttle, or pedaling, the motor has started applying power and not applying power, repeatedly. Essentially jerking the bike forward in little increments. like hitting the throttle over and over on and off.
  • When lifting the back wheel off the ground it seems to spin no problem (though even on 4 it seems somewhat slow).
  • Every so often when it gets it rolling it'll hold power at the proper speed, but generally when pedaling up to speed it still jerks on and off
  • I drive it in a pretty easy gear/higher RPM so to let the motor spin up and limit the initial torque required.
  • I have noticed recently a "Error 30" coming on screen mid ride (then disappearing). Sometimes I can fix it when when a cable could be jiggled near the motor? Though the bike and display never shuts off and still provides power with the error showing- i am afraid one of the controller's wires between the frame and motor could be crushed? - battery line has no compression
  • I've read it could be low voltage on the battery, but the battery is new, always topped off over night and never ridden below 3 cels.

Key Stats & Tests
  • The battery is only a few months old
  • 850 miles total on it and the motor
  • Ride it 3x a week for 7.5 mi at a time 2x a day
  • Plugged in a new display and no difference
  • Changed the harness cable and no difference
  • Felt like a faulty break lever but likely not.
  • I have a spare controller to install, but that would be a huge pain to re wire and solder if it's something else.
  • The motor may also need a stabilizer since it drops and flips up during application of power, but that never was an issue before and I'd assume it would still run.

Please help as this is my only means of commuting!
 
bpmessenger said:
I have a BBS02B 750W which was fine for the past few months (bought maybe a year ago, max). Recently, when hitting the throttle, or pedaling, the motor has started applying power and not applying power, repeatedly. Essentially jerking the bike forward in little increments. like hitting the throttle over and over on and off.
Does anything change on the screen during these moments?


  • When lifting the back wheel off the ground it seems to spin no problem (though even on 4 it seems somewhat slow).
  • Every so often when it gets it rolling it'll hold power at the proper speed, but generally when pedaling up to speed it still jerks on and off

  • That could indicate a problem only under load, which may mean the battery is dropping under load enough to trigger LVC on the BBS02. You'd probably see this on the display's battery meter, if it lasts long enough to show up, but if the meter has slow averaging, it won't change fast enough to show you this. In that case, you'd need a fast-enough-refreshing voltmeter display on the battery wires to see it. (an analog voltmeter would, for instance; many but not all digital ones probably would; some might have slow enough refresh to not always catch quick voltage drops).

    [*]I have noticed recently a "Error 30" coming on screen mid ride (then disappearing). Sometimes I can fix it when when a cable could be jiggled near the motor? Though the bike and display never shuts off and still provides power with the error showing- i am afraid one of the controller's wires between the frame and motor could be crushed? - battery line has no compression

    I think 30 is a comm error (you'd need to check the manual or one of the threads here on ES about BBS02 error codes). If it is, then you could have a connection problem between controller and display. That is most often at the actual connector, but could be in a cable itself, usually near where it exits either the connector base or the motor casing.

    Sometimes it's a corrosion problem at the point where this cable plugs into the controller inside the casing, if it's not soldered directly to the board.

    [*]The motor may also need a stabilizer since it drops and flips up during application of power, but that never was an issue before and I'd assume it would still run.
    But the movement may have damaged the cable at any point where it gets flexed during this motor movement.
 
Thanks for the reply here!

To answer your questions. The display generally doesn't change for anything out the normal when this happens. However last night when testing I got a pretty weird out of battery icon thrn it could come back, I restarted and that didnt happen again

I believe it could be the controller (as well?) as you mentioned due to the error 30. Which was much more frequent in turning on last night to point where the bike just didn't even get power to that pedals (but would turn on)

I disassembled everything last night and found that the controller wire was terribly smashed where the motor hits it, to the point that some of the wires internally were hanging on by a thread if at all. I cut out the bad section and re soldered all the tiny connections back together. As of now (haven't ridden it) it seems to have gotten rid of the error 30. I'm waiting on an extension cable to re mount everything (too short after cutting the bad spots) hopefully this error 30 was the root of everything and the battery is OK. Will find out this weekend.
 
So I found that a bunch of harness wires were crushed so I re soldered them together and everything worked well.. Until this am..

I don't get any comm error 30 and all the wires are still in tact and isolated from each other. I apply the power and the bike revs, but then goes into this "dying battery" type of mode where it doesn't apply power anymore with load.

Even when lifted off the ground. The wheel revs uo then the crank spins slooollllwly. I take remove the throttle, give it a second, and it does the same thing. Thoughts??

Video attached at link below
https://drive.google.com/file/d/1YcsM_OdGdEDMfKxPhbLsCyrplz_wmUby/view?usp=sharing
 
bpmessenger said:
I don't get any comm error 30 and all the wires are still in tact and isolated from each other. I apply the power and the bike revs, but then goes into this "dying battery" type of mode where it doesn't apply power anymore with load.

Even when lifted off the ground. The wheel revs uo then the crank spins slooollllwly. I take remove the throttle, give it a second, and it does the same thing. Thoughts??
What does the battery voltage read (both with a multimeter, and on the bike display) when it does this?

Does it drop at all during the throttle-up, vs just sitting there?

If it does, it's probable that the controller is detecting this and going into a protection mode. It could be that the controller has a wrong setting (which may or may not be visible on the display; just changing the LVC setting to something else, saving, turning it off, then back on, then changing to what it should be for your battery, then saving, turning it off, then back on, might fix that; or a full reset of the settings and then a power cycle, then resetting it back up and another power cycle).


If the system does the same thing even with the chain removed from the crank chainring (so there is no connection to the wheel, and thus less load), it means it's not likely caused by an "overload" being sensed (even if there isn't really an overload). It's likely the battery doesn't sag in this case, as well, so it's probably not the LVC.

Similarly, if it happens also with very slowly increasing application of throttle (vs sudden full application), it's probably not the loading or battery sag.

In those cases, it could be that it a sensor is not providing the correct input to the controller, such as a wheel speed sensor (at the wheel), or a motor / gear speed sensor (if there is one, it'd be inside the motor casing).

I don't remember which sensors the BBS02 system has / uses, though.

It's also possible that one of the wire damages shorted something together (battery voltage to a data line, etc) and permanently damaged a part; this could be at either end of that wire...not knowing which ones, if any, ever shorted together, I can't say which parts it might be. But if the throttle and display wires both go thru the damaged area, either one (or the controller) could be damaged.

If it's a throttle problem, it's easy enough to verify, as the voltage it outputs over it's range will be wrong. It should be somewhere around 0.8v-1.something volts at it's "off" state, and smoothly increase up to around 3-4.something v at it's highest point. If it goes up to 5v on the output, and the controller only shows this problem at that point, it means the throttle is giving too high a voltage and the controller is protecting against a throttle fault.

A display or controller fault would be harder to diagnose. :(
 
How would i test the battery voltage adn all the below with a multimeter when it goes? Any instrution would be super helpful. I dont have a complicated display so unfortunately no way to really tell there.

I have a new controller i may just try to install tonight and see where that goes....
 
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