BBS HD power cutting off and on

[rgvkid]

hi all,

my bike has now become unuseable, sadly. motor has only done about 400 miles.
issue started with the PAS level changing by itself, especially (and probably exclusively) when using the throttle. what then started happening is the motor cutting off and on, sometimes only very briefly, other times the motor cuts and then only briefly cuts on/off again.
when it's happening, either the throttle works or it's non-responsive, doesn't seem any pattern to it.
on a test drive few weeks back, after dismantling button pod for PAS, it then performed fine until i used the throttle, then PAS would jump about, motor would cut etc.

i've swapped out the throttle, main wiring from where motor plugs into it, changed display and button pod, removed battery to check connections etc. and can't find anything that would cause this.

if anyone has any ideas at all, they would be much appreciated, as i'm coming to the conclusion it's something in the motor itself as i've replaced almost everything else.
i suspect it's not the battery, as the display never flickers/switches off , it remains on whether motor working or not. i suspect if it was a battery power/BMS issue the display would flicker etc.

bizarrely yesterday when i fitted new display and button pod, took it for ten min test drive and it performed as expected, not a glitch. yet this morning tried to use it for work and got a few mins from house before motor hesitated a few times, then started cutting out entirely.

thanks,
colin

 

[Nealh]

One would suspect a faulty controller , any error code.

 

[trevor brooker]

When I fault finded I found it best to replace one part at a time.

I had an intermittent fault with my BBSHD that caused it to stop working. It turned out to be battery fault, but every test I did on the battery showed no problems.

So easiest part to replace is the battery, then the controller.

I got a no name cheap battery from ebay just to test my problem & found it cured it.

 

[rgvkid]

Thanks for replies, no error codes at all. Have literally replaced or unplugged everything apart from battery and motor. The battery was quite a dear one and I would hope its not that, but wouldn't rule it out.
I do have a spare motor which had faulty Hall sensors, so could conceivably swap controller. It's only done 400 odd miles, so find it hard to believe anything physically wrong with it, seems fine when it's actually working.
Any other suggestions more than welcome, but I think it has the be something in the motor, presumably the controller.... Or maybe battery as u suggest, tho fact display remains constant throughout when motor cutting off and on suggests to me not battery power issue.
Cheers

 

[matthewslack]

 

[rgvkid]

hi all, so has anyone come across a wonky controller which doesn't show error codes ? looks easy enough to replace and i do have a spare, but would be good to know before spending the time if this is the likely issue, considering i've replace everything else outwith the motor. cheers,

 

[matthewslack]

Rereading the thread, a bit of a long shot...

It worked for a while after display and buttons replaced. That would have split and reconnected various connectors, and the disturbance might have temporarily cleared a poor contact fault.

Worth exercising the same connectors again?

 

[rgvkid]

thanks for that, i changed back to original display and the fault was still there, tjhen back to new display and still had the issue. so not sure if just hit lucky for initial test with new display/button pod, weird though that it worked perfectly for a ten minute test where i was off and on throttle, changing PAS etc, yewt next day got literally minutes from the house before it hesitated a few times, then got worse to the point that motor barely cutting in, over a period of a minute or so going from hesitation to mostly not working.
i think next step is to replace the controller, as this looks relatively easy from youtube videos.
and if it's not that, then gaaaaawd only knows
cheers

 

[saneagle]

thanks for that, i changed back to original display and the fault was still there, tjhen back to new display and still had the issue. so not sure if just hit lucky for initial test with new display/button pod, weird though that it worked perfectly for a ten minute test where i was off and on throttle, changing PAS etc, yewt next day got literally minutes from the house before it hesitated a few times, then got worse to the point that motor barely cutting in, over a period of a minute or so going from hesitation to mostly not working.
i think next step is to replace the controller, as this looks relatively easy from youtube videos.
and if it's not that, then gaaaaawd only knows
cheers

The only thing that goes down with use is the battery.

 

[rgvkid]

Hi, so are you suggesting it could well be the battery? I can try charging it and see if it behaves when fully charged.
Main reason I didn't think it was battery is its a decent quality branded cell battery, and also that the display remains solid, doesn't flicker, doesn't power cycle etc. Which suggested to me the issue lay elsewhere.
Cheers

 

[Woosh]

thanks for that, i changed back to original display and the fault was still there, tjhen back to new display and still had the issue. so not sure if just hit lucky for initial test with new display/button pod, weird though that it worked perfectly for a ten minute test where i was off and on throttle, changing PAS etc, yewt next day got literally minutes from the house before it hesitated a few times, then got worse to the point that motor barely cutting in, over a period of a minute or so going from hesitation to mostly not working.
i think next step is to replace the controller, as this looks relatively easy from youtube videos.
and if it's not that, then gaaaaawd only knows
cheers

the fault is not clear cut from your description. I would temporarily disconnect the brake sensors then speed/gear sensor when the motor starts to misbehave and test only using the throttle. That would remove a few variables.

 

[rgvkid]

thanks, should have said i've disconnected throttle, gear change sensor and brake sensor/s one at a time, and the issue was still there using PAS only with no external sensors connected.
cheers,

 

[Woosh]

you have now reduced the possible candidates to: pas sensor inside the motor, Hall sensors and controller. Next step: use the throttle to remove the PAS from the suspects.

 

[rgvkid]

thanks, throttle also causes engine to cut off and on (usually just gives quick 1/2 second burst of power then nothing), not quite sure how to remove PAS from suspect list as it also causes the issue ?
my previous motor had hall sensors fault, but it actually showed as an error code, not sure how accurate these error codes are when there's an issue tbh

 

[Woosh]

you can open the case and unplug the PAS from the controller.
You have probably narrowed the suspects down to Hall sensors or controller. I said probably because all the sensors use the 5V line. Still there is no clear proof. The reduction in power indicates likelihood of Hall sensor fault because the motor still spins so throttle/PAS/controller is/are still working.
I would usually swap out the controller here but appreciate that not many members have a spare controller lying around.

 

[Bikes4two]

I'm following this thread with interest (as in still learning about things - every day's a school day isn't it?).

Apologies if I've missed it @rgvkid, but are we talking about a hub motor here rather than a mid-drive? And what sort of battery is it - Hailong style, Bottle battery, Rack mounted?

And to all those more knowledgeable than I, would not an intermittent BMS give similar symptoms?

 

[Woosh]

The op has a Bafang BBS HD. If and when the bms shutdowns, you will have to restart the LCD. When the motor stutters or loses 90% of its power, 9 times out of 10 one of the 3 hall sensors shorted.

 

[rgvkid]

thanks all for the input, and it now appears to be fixed. i am one of those lucky few with a spare controller, so i swapped it and it's now done approx 30 miles over 6 or 7 journeys and hasn't missed a beat.
interestingly, i'm guessing something in the controller has maybe been on it's way out for a while, as for a long time now the PAS has changed itself sometimes, mostly (maybe entirely) when the throttle is used.
this became more frequent over time, and then other things like sometimes the PAS would stop working, throttle would work but no PAS etc.
there was a fair bit of white gunk at bottom of controller casing (would guess maybe salt off the roads) and actual moisture on the black connector (silicon from factory at either end of it, so maybe this as opposed to controller itself?).
cleaned the white stuff out, and used silicon with the factory gasket , lots of youtube videos mention the factory gaskets are rubbish and water ingress often an issue.
cheers,
colin