Bafang PAS intermittent problem BBS01

[Rob Fawcett]

I'd be grateful for diagnostic suggestions:
Periodically my BBS01 PAS stops working but the throttle continues to function fine.
It seems to happen quite randomly, and not coinciding with a pattern of use (such as when cold or after a hard climb).
The sensor LED is flashing every time the magnet passes it, and the display is showing no error and still shows my speed when the PAS is not working correctly.
Yesterday the PAS worked for about 15 miles, dropped out for maybe ten miles, but was working again by the time I got home. On other occasions it has not been working from the moment I set off.
I hope this might be a loose connection and would be glad of any pointers to such a possible failure point or any other likely issue. I have seen that replacement PAS boards can be bought, and would also be glad of thoughts about this. I'm experienced at soldering and have a multimeter.
Thank you!

 

[wheeliepete]

The fact it works fine some of the time would suggest a loose connection rather than damage to the magnetic ring. You could remove the controller (3 allen keys on the drive side) and check the small 4 pin connector on the sensor is fully connected. Bafang cover it in silicon, but sometimes the plug is not fully engaged. Remove the silicon and ensure it is fully fitted.

 

[Rob Fawcett]

The fact it works fine some of the time would suggest a loose connection rather than damage to the magnetic ring. You could remove the controller (3 allen keys on the drive side) and check the small 4 pin connector on the sensor is fully connected. Bafang cover it in silicon, but sometimes the plug is not fully engaged. Remove the silicon and ensure it is fully fitted.

Thank you, Pete, I'll take a look at that...

R

 

[KirstinS]

It could be something simpler maybe ? Such as the speed sensor and magnet not being quite close enough. Bit road jiggle and they get close enough, bit more and they don’t

I say this as it’s happened to me. I strengthened the sensor mount with a bit of sugru and a small blob of lock tite on the magnet so it doesn’t swivel on the spoke

This is on my hardtail which does get thrashed around South Downs so serious bumps occur !


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[Rob Fawcett]

It could be something simpler maybe ? Such as the speed sensor and magnet not being quite close enough. Bit road jiggle and they get close enough, bit more and they don’t

I say this as it’s happened to me. I strengthened the sensor mount with a bit of sugru and a small blob of lock tite on the magnet so it doesn’t swivel on the spoke

This is on my hardtail which does get thrashed around South Downs so serious bumps occur !


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Thanks, I'm South Downs too, hardtail with suspension seat post, and recently had an internal battery weld give out on a fast downhill: that chalk can get chunky ;-)

In this case, though, I am still getting accurate speed readings even when the PAS drops out, so I don’t believe it's the sensor. Normally, too, when the magnet gets knocked askew I get an error on the display, I think Error Code 13. I'm getting no error indication on the display with this problem, just no PAS.

R

 

[KirstinS]

Thanks, I'm South Downs too, hardtail with suspension seat post, and recently had an internal battery weld give out on a fast downhill: that chalk can get chunky ;-)

In this case, though, I am still getting accurate speed readings even when the PAS drops out, so I don’t believe it's the sensor. Normally, too, when the magnet gets knocked askew I get an error on the display, I think Error Code 13. I'm getting no error indication on the display with this problem, just no PAS.

R

Apologies rob, that was me posting without reading properly first

The previous post seems your best first port of call


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[minexplorer]

I'd be grateful for diagnostic suggestions:
Periodically my BBS01 PAS stops working but the throttle continues to function fine.
It seems to happen quite randomly, and not coinciding with a pattern of use (such as when cold or after a hard climb).
The sensor LED is flashing every time the magnet passes it, and the display is showing no error and still shows my speed when the PAS is not working correctly.
Yesterday the PAS worked for about 15 miles, dropped out for maybe ten miles, but was working again by the time I got home. On other occasions it has not been working from the moment I set off.
I hope this might be a loose connection and would be glad of any pointers to such a possible failure point or any other likely issue. I have seen that replacement PAS boards can be bought, and would also be glad of thoughts about this. I'm experienced at soldering and have a multimeter.
Thank you!

Try and find my threads on my own issue with random PAS function on a bbs01 .It was the controller in the end.The throttles played up too.Was all started by rain in the throttles i tried 2 the second being fine until rain also.Strangely caused damage to the function of PAS.

 

[pn_day]

I would also suspect the controller, or the actual PAS disk which I think is internal on a BBS. I think you could either buy a new controller (internal), or do the mod to allow an external controller - and then you can use an external PAS as well. Not as neat, but might be easier to troubleshoot.

 

[egroover]

I would also suspect the controller, or the actual PAS disk which I think is internal on a BBS. I think you could either buy a new controller (internal), or do the mod to allow an external controller - and then you can use an external PAS as well. Not as neat, but might be easier to troubleshoot.

Apologies for the thread ressurection but today I'm having similar issues where I'll be riding along and intermittently there's no assist on my BBS01b. The display is on and showing speed, voltage etc as normal but the power displays 0W. Then it'll start assisting as normal. I've check cables etc plugged in all seems fine. As I say, works fine most of the time. Powering off from the display doesn't seem to kick it back into life when it fails.
I'm suspecting an intermittent controller or maybe more likely the PAS magnet? If the latter, are they easy to source and fit ?

Cheers all

 

[peter.c]

Can you try it on a throttle this will help to find if it is controller or pas fault ?

 

[egroover]

Can you try it on a throttle this will help to find if it is controller or pas fault ?

Hi Peter, good shout that, I have one with the kit never used, will fit and test. Cheers

 

[egroover]

Well fitted throttle, took bike out today and could I get it to go wrong ? No, performed perfectly, no PAS drop outs whatever I threw at it. Turn off, turned on, throttle on and off, assist levels up and down, smooth and bumpy terrain etc etc

I can only assume the problem will resurface at some point and/or there was some moisture in there somewhere and it's dried out...time will tell/ Will leave throttle on for the time being to test if the issues resurfaces.

Forgot how much fun throttles are off road

 

[guerney]

I can only assume the problem will resurface at some point and/or there was some moisture in there somewhere and it's dried out...

I'd make certain of waterproofing, if it does turn out to have been caused by moisture. When I fitted my new controller about 2,300+ km ago, the floppy rubber gasket between controller and motor was very tricky to keep in place, so I applied a thin layer of silicone sealant on the motor casing edge first. Once the gasket was stuck on, I applied a second thin layer of silicone sealant over the gasket before bolting the controller and motor together tight. I also made rain hat for the display, and covered nearly every connector with self-adhesive 4:1 marine heat shrink plus self-amalgamating rubber tape. It sounds a bit OTT, but I haven't had any issues with water ingress despite hours of rain. My BBS01B motor kit has also survived complete submersion for 13 seconds, where the water level was above both pedals. The bike created a bow wave as I pedalled my way out of that pond which appeared in the road after a sudden thunderstorm. The bow wave kept water away from the battery - there's no way I could have done that without electrcal assistance.

 

[joelectric]

Well fitted throttle, took bike out today and could I get it to go wrong ? No, performed perfectly, no PAS drop outs whatever I threw at it. Turn off, turned on, throttle on and off, assist levels up and down, smooth and bumpy terrain etc etc

I can only assume the problem will resurface at some point and/or there was some moisture in there somewhere and it's dried out...time will tell/ Will leave throttle on for the time being to test if the issues resurfaces.

Forgot how much fun throttles are off road

Keep the throttle, life's too short.

 

[egroover]

I'd make certain of waterproofing, if it does turn out to have been caused by moisture. When I fitted my new controller about 2,300+ km ago, the floppy rubber gasket between controller and motor was very tricky to keep in place, so I applied a thin layer of silicone sealant on the motor casing edge first. Once the gasket was stuck on, I applied a second thin layer of silicone sealant over the gasket before bolting the controller and motor together tight. I also made rain hat for the display, and covered nearly every connector with self-adhesive 4:1 marine heat shrink plus self-amalgamating rubber tape. It sounds a bit OTT, but I haven't had any issues with water ingress despite hours of rain. My BBS01B motor kit has also survived complete submersion for 13 seconds, where the water level was above both pedals. The bike created a bow wave as I pedalled my way out of that pond which appeared in the road after a sudden thunderstorm. The bow wave kept water away from the battery - there's no way I could have done that without electrcal assistance.


View attachment 52261

Thanks guerney. I've got self amalgamating tape on my shopping list, I reckon that and heat shrink will keep things dry.
I'm lucky to have enough parts for another BBS01b build on a Boardman hybrid base. Gonna keep this bike for dry use and long tours here in the UK and when I go on tours to France, Belgium, Germany etc so it stays fresh with low use and will not have the abuse of daily rides and the British weather. Just raiding my parts bins for new spares I have accumulated over the years when I saw a deal. Looks like the only thing I will need that I haven't a spare is a Selle Royal Respiro saddle

 

[saneagle]

Thanks guerney. I've got self amalgamating tape on my shopping list, I reckon that and heat shrink will keep things dry.
I'm lucky to have enough parts for another BBS01b build on a Boardman hybrid base. Gonna keep this bike for dry use and long tours here in the UK and when I go on tours to France, Belgium, Germany etc so it stays fresh with low use and will not have the abuse of daily rides and the British weather. Just raiding my parts bins for new spares I have accumulated over the years when I saw a deal. Looks like the only thing I will need that I haven't a spare is a Selle Royal Respiro saddle

A dob of silicone grease is all you need for the connectors.

 

[guerney]

I've got self amalgamating tape on my shopping list, I reckon that and heat shrink will keep things dry.

Screwfix also sell self-amalgamating rubber tape, I bought 10m from here:

Pardon our interruption...

Self-adhesive 4:1 marine heat shrink can start large enough to slip over even the largest connectors. I got stiffed by this seller twice, when I'd ordered 2m lengths, but he slightly more than made up for it after I complained he'd only sent me 1m lengths, sending three 1m lengths - bear in mind the widths quoted are when measured flat:

4:1 Black Adhesive Heat shrink Waterproof HeatShrink Glue Lined Tubing Sleeving | eBay

Its high shrink ratio makes it ideal for sealing large components and irregular shapes. NOT the lay flat width of the heat shrink. As a guide, the lay-flat width of our heat shrink is below Shrink Temperature: 90 °c.

www.ebay.co.uk