BBS02b Failure

MontyPAS

Esteemed Pedelecer
May 16, 2020
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Went to take my BBS02b 500w 36v bike for a ride around the woods today, set the PAS to 3 of 5 levels, started to pedal, bike suddenly lunged forward and died.
Display shows all functionality.
No power from PAS.
Throttle worked momentarily.
Battery is a fully charged 36v 17Ah
Unplugged battery, reconnected tried throttle (probably a mistake?), display showed error 12? Current sensor????

Unit is only 8 months old and covered around 700 miles light track miles.

Controller???? Any ideas??
 

vfr400

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Jun 12, 2011
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Basildon
Sounds like a blown mosfet. You have to open up the controller compartment to test. It could be a blown hall sensor, but that's not very common.

Measure the resistance between each phase wire and the positive battery wire, then repeat for the negative. The readings should be in the KOhm range.
 
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MontyPAS

Esteemed Pedelecer
May 16, 2020
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Sounds like a blown mosfet. You have to open up the controller compartment to test. It could be a blown hall sensor, but that's not very common.

Measure the resistance between each phase wire and the positive battery wire, then repeat for the negative. The readings should be in the KOhm range.
Thanks VFR. I suspected that.
Its been very wet down here in Cornwall the last few weeks and I have still been riding in it, I would not be surprised if water ingress is also an issue?
 

MontyPAS

Esteemed Pedelecer
May 16, 2020
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Pretty sure there was someone on here who fitted an external controller? Was it successful?
If so it has got to be cheaper and more reliable than the weak bafang ones?
 

peter.c

Esteemed Pedelecer
Apr 24, 2018
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My bafang just blew a controller new one was £75.00 from green bike kit arrived quickly from China the new one has the uprated mosfets
PS you must give your mid drives hill climbing hell or was it on a 42 volt diet ?
 
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MontyPAS

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May 16, 2020
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My bafang just blew a controller new one was £75.00 from green bike kit arrived quickly from China the new one has the uprated mosfets
PS you must give your mid drives hill climbing hell or was it on a 42 volt diet ?
We've got some steep hills in Cornwall. Did you buy the controller recently (post Brexit exit)?
 

Nealh

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Aug 7, 2014
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Jarob has done 2 or 3 conversions to KT external successfully, I tried my BBS01 but it wouldn't run in any of the 36 combo's properly so I abandoned it to try again. I never did try again but will do one day as I have a couple of spare 6 fet and a 9 fet sq wave one.
 
D

Deleted member 33385

Guest
Thanks VFR. I suspected that.
Its been very wet down here in Cornwall the last few weeks and I have still been riding in it, I would not be surprised if water ingress is also an issue?

WHAT?!?!?!? Water ingress??!?!?? Is this a common experience with Bafang motors? If so, I'll have to find some way to seal the damn thing more effectively.
 
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MontyPAS

Esteemed Pedelecer
May 16, 2020
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Jarob has done 2 or 3 conversions to KT external successfully, I tried my BBS01 but it wouldn't run in any of the 36 combo's properly so I abandoned it to try again. I never did try again but will do one day as I have a couple of spare 6 fet and a 9 fet sq wave one.
Thanks Nealh, I think I've found a little info here https://www.pedelecs.co.uk/forum/threads/bbs01-to-kt-controller-mod.34880/.
Once I have tested the MosFets on the old Bafang controller and confirmed failure, probably will give this a go! I have a couple of KT controllers at hand.
Any further info from yourself or Jarob would be a great help
 

MontyPAS

Esteemed Pedelecer
May 16, 2020
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WHAT?!?!?!? Water ingress??!?!?? Is this a common experience with Bafang motors? If so, I'll have to find some way or sealing the damn thing more effectively.
Its a high possibility
 

vfr400

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Jun 12, 2011
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WHAT?!?!?!? Water ingress??!?!?? Is this a common experience with Bafang motors? If so, I'll have to find some way or sealing the damn thing more effectively.
Yes, one even spontaneously caught fire because of it while it was switched off at the LCD.. His controller wasn't properly encapsulated. Water got in and shorted one of the mosfets, which happen to sit right at the bottom where the water accumulates. Lucklly, the owner was nearby when it started crackling then billowed out smoke.

Only the BBSHD has a sealed controller compartment, so any of the others could get shorted phase wires
 
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D

Deleted member 33385

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Yes, one even spontaneously caught fire because of it. His controller wasn't properly encapsulated. Water got in and shorted one of the mosfets, which happen to sit right at the bottom where the water accumulates. Lucklly, the owner was nearby when it started crackling then billowed out smoke.

Well that's just marvellous, isn't it? Black silicone sealant all along the join? What do you reckon?
 

Nealh

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Aug 7, 2014
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MontyPAS

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May 16, 2020
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Well that's just marvellous, isn't it? Black silicone sealant all along the join? What do you reckon?
Think the water gets in, through the cable entry gland at the bottom of the motor (poor design).
Silicone might help..... wouldn't like to guarantee it?
 
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MontyPAS

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May 16, 2020
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I removed the controller from the housing so any excess wiring could all be retained inside.
Yes, saw that in the post. Will get the controller off in the next couple of days (weather permitting) for testing!
Then may tap your experience regarding / confirming connections and parameter settings on the KT
 

vfr400

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Jun 12, 2011
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Think the water gets in, through the cable entry gland at the bottom of the motor (poor design).
Silicone might help..... wouldn't like to guarantee it?
Rather than seal, I prefer to leave a way out for any water that gets in. I've seen two many drowned controllers after people attempted to seal them.
 
D

Deleted member 33385

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Think the water gets in, through the cable entry gland at the bottom of the motor (poor design).
Silicone might help..... wouldn't like to guarantee it?

If it's just the entry glad, Sugru might be worth a shot....
 

MontyPAS

Esteemed Pedelecer
May 16, 2020
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Rather than seal, I prefer to leave a way out for any water that gets in. I've seen two many drowned controllers after people attempted to seal them.
Tend to agree / disagree.
Most IP rated external electrical boxes I used to install, have a small drainage hole for that very purpose!
They are static and do not move. The hole is also for condensation drainage as well, so it works fine!

With a low slung motor mounted on the bottom bracket, personally I think a drainage hole would serve no purpose and would cause more problems than serve. As the moisture is ingress not condensation?

If water can find its way in...... it will!
 
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MontyPAS

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cannon

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Jan 17, 2019
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As the motor is in line of fire from the front wheel, some sort of shield would go a long way to reduce ingress I think.
 
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