Intermittent Power Loss - Woosh Big Bear
Intermittent Power Loss - Woosh Big Bear
Hello all, and thanks for accepting me - first post.
My 5-year-old Woosh Big Bear (front wheel motor) has developed an irritating intermittent fault over the past three months. Essentially, it fails to pick up power straight away after slowing down.
Typically it happens after coasting down a hill. When I start pedalling again, instead of picking up power after a single revolution, it seems to run on little or no power for typically 10 seconds or so. But this varies considerably - sometimes there’s no power loss, occasionally it’s so prolonged that I’ve had to switch the bike off and on again. It doesn’t seem to be a complete cutout - so I don’t think it’s as simple as a loose power lead, for example.
I’ve been in discussion with Woosh, who have been very helpful but are unable to put their finger on a likely solution. I’ve checked the battery mounting and cleaned and WD40’d the connections. I’ve also checked the crank-mounted sensor - it looks ok (close to the disk and running true).
If anyone has any ideas I’d be really grateful. I’ve had helpful chats with a local repair shop (listed on the Woosh main site) but he can’t figure out the issue either.
My 5-year-old Woosh Big Bear (front wheel motor) has developed an irritating intermittent fault over the past three months. Essentially, it fails to pick up power straight away after slowing down.
Typically it happens after coasting down a hill. When I start pedalling again, instead of picking up power after a single revolution, it seems to run on little or no power for typically 10 seconds or so. But this varies considerably - sometimes there’s no power loss, occasionally it’s so prolonged that I’ve had to switch the bike off and on again. It doesn’t seem to be a complete cutout - so I don’t think it’s as simple as a loose power lead, for example.
I’ve been in discussion with Woosh, who have been very helpful but are unable to put their finger on a likely solution. I’ve checked the battery mounting and cleaned and WD40’d the connections. I’ve also checked the crank-mounted sensor - it looks ok (close to the disk and running true).
If anyone has any ideas I’d be really grateful. I’ve had helpful chats with a local repair shop (listed on the Woosh main site) but he can’t figure out the issue either.
Re: Intermittent Power Loss - Woosh Big Bear
I can't see why it would cause those issues, but worth checking the battery in the LCD.
Could be the cable from the crank sensor.
Was that regular WD40 or their contact cleaner? Regular WD40 is good at getting rid of damp, but not that good as a switch cleaner.
Also try posting at https://www.pedelecs.co.uk/forum/forums ... ussion.42/; a bigger community than here and some real experts.
Could be the cable from the crank sensor.
Was that regular WD40 or their contact cleaner? Regular WD40 is good at getting rid of damp, but not that good as a switch cleaner.
Also try posting at https://www.pedelecs.co.uk/forum/forums ... ussion.42/; a bigger community than here and some real experts.
Re: Intermittent Power Loss - Woosh Big Bear
Thanks - I’ll give all these a go.
Re: Intermittent Power Loss - Woosh Big Bear
I would check the brake levers/ cutoff/s are not sticking or are slow to fully seat back.
Also have a look at the BB sensor & magnet disc, ensure the magnet face is clean and the gap between sensor face and disc is 1mm. Check the magnet disc is firm on the axle and can't rotate around the axle manually.
Also have a look at the BB sensor & magnet disc, ensure the magnet face is clean and the gap between sensor face and disc is 1mm. Check the magnet disc is firm on the axle and can't rotate around the axle manually.
Re: Intermittent Power Loss - Woosh Big Bear
Will do. The sensor gap is more like 3-4mm, so I’ll clean and adjust that. Thank you.
Re: Intermittent Power Loss - Woosh Big Bear
In that case then 3 - 4mm is way too much for the Hall to pick up the magnet.
Re: Intermittent Power Loss - Woosh Big Bear
Right. That’s very useful - thanks. I’ll adjust it tomorrow and test it out.
Re: Intermittent Power Loss - Woosh Big Bear
Thanks for all the advice to date. I moved the sensor to about 1mm from the disk, and cleaned/WD40’d and dried the whole area with the bike upside down. No luck so far.
With it upside down it’s easier to gauge what’s happening. When working normally, a gentle turn of the pedals kicks the motor into full power pretty much straight away. It still does this on occasion. At other times, with the pedals gently turning, the power cycles on and off, and power seems much more dependant on pedal speed. (I know this is normal for many bikes, but the Woosh has always taken off immediately. I could, for instance, turn the pedals slowly using no leg power at all, and the bike would happily cruise at 15mph). In any event, the motor power does not seem adequate for much of the time. Nothing mechanical is binding.
Hopefully this might generate further ideas. Again, many thanks for all the advice.
With it upside down it’s easier to gauge what’s happening. When working normally, a gentle turn of the pedals kicks the motor into full power pretty much straight away. It still does this on occasion. At other times, with the pedals gently turning, the power cycles on and off, and power seems much more dependant on pedal speed. (I know this is normal for many bikes, but the Woosh has always taken off immediately. I could, for instance, turn the pedals slowly using no leg power at all, and the bike would happily cruise at 15mph). In any event, the motor power does not seem adequate for much of the time. Nothing mechanical is binding.
Hopefully this might generate further ideas. Again, many thanks for all the advice.
Re: Intermittent Power Loss - Woosh Big Bear
Do these sensors have any diagnostics built-in, such as indicator LEDs?
Thanks
Jonathan
Thanks
Jonathan
Re: Intermittent Power Loss - Woosh Big Bear
Nothing visible, Jonathan. It’s a pretty basic machine!
Re: Intermittent Power Loss - Woosh Big Bear
I thought the Woosh Big Bear sensor had a Red led on the sensor head, if so it should blink as the magnet passes.
One can try testing the PAS voltage via the wiring, if it uses the JST SM3 wire connectors that allow for meter probes to placed up the ack of them.
With a meter set at 20vdc and the bike power on probe between the Gnd wire and 5v to check 5v is present on the Hall sensor, if so then try probing between Gnd and the other (signal wire) whilst having someone turning the cranks. One should see the voltage change from 5v to 0v or a very low value as it passes each magnet.
One can try testing the PAS voltage via the wiring, if it uses the JST SM3 wire connectors that allow for meter probes to placed up the ack of them.
With a meter set at 20vdc and the bike power on probe between the Gnd wire and 5v to check 5v is present on the Hall sensor, if so then try probing between Gnd and the other (signal wire) whilst having someone turning the cranks. One should see the voltage change from 5v to 0v or a very low value as it passes each magnet.
Re: Intermittent Power Loss - Woosh Big Bear
Thanks
Jonathan
Jonathan
Re: Intermittent Power Loss - Woosh Big Bear
Hi Hemo. Is that the sensor by the rear wheels spokes - not the one on the crank? I think there is a red led there - though I’ve never seen it light up…. But I’ll give that a try - thanks for the info.
Re: Intermittent Power Loss - Woosh Big Bear
No, the wheel one is the speed sensor, though it may be possible the rear sensor if not picking up properly may affect how PAS works. I have never actually worked on a Big Bear but do have a Big Bear conversion kit, my hub motor has an internal speed sensor so never an issue.
Does the KM J lcd display work ok and show speed.
Does the KM J lcd display work ok and show speed.
Re: Intermittent Power Loss - Woosh Big Bear
I would carry out the electrical test I mentioned on the sensor as any anomaly will show up in the reading and would mean a faulty PAS Hall sensor.