bbs02 power cutting out

Gurnard

Pedelecer
Dec 30, 2015
36
5
53
I have a bbs02 motor that I have ridden about 8500 Kms with. It is a 350w 36v. This week the power has started to cut out. I haven't had any problems before. When riding on the flat Pas 4out of 5 and changing to 5,6,7 out of an 8 gear bike everything shuts off. Nothing on the display or light on the gear change module. It is as though the battery is turned off. If I turn the battery switch off and on and then restart the motor it continues but only for a very short distance then it is gone again.

Any ideas? I rewired the connections from the battery and contact is good there. Is it a controller issue or battery? The battery is younger than the motor/controller by about a year. No errors on display. I really don't know where I should start.
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
19,991
8,173
60
West Sx RH
If you have a throttle and it works ok then the PAS pcb (small) may need replacing.
If throttle reacts the same then possibly the battery isn't able to supply the current or the controller has an issue. controllers on older BBS02 have the older mosfets which appear to have heat issues, BBS02 has upgrade mosfets for better reliability.
 
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vfr400

Esteemed Pedelecer
Jun 12, 2011
9,822
3,985
Basildon
If the LCD goes off, it's because the voltage from the battery has been interrupted, so you have to look at your battery and its connections for a solution.. Measure the voltage hot off the charger and again immediately after it cuts out.
 
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Gurnard

Pedelecer
Dec 30, 2015
36
5
53
OK thanks for the replies. I ran it on the throttle with the wheel up in the garage, different gears and PAS for about 20 minutes and all works fine. Put it with me on it on the road and it cut out as before, obviously more load. The volts from the digimeter read 41 (is 36v but I guess it could be a bit out).
So from the advice it looks like it is the battery though the connections are ok, or I guess it would cut out when throttling with the wheel up. So what is happening is it because it is a heavier draw on the battery and the battery cannot take it or something else? Just trying to understand the theory I don't know much about electronics.
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
19,991
8,173
60
West Sx RH
Sounds like battery can't handle higher current draw when in PAS4 with higher gear range.
Try again in the garage with wheel up, whilst in PAS4 in high gear try apllying the rear brake but not hard enough to stop the rotation to provide a current load and see if it cuts out . Ideally you also need to have a volt meter wired up as well so you can see what happens to the volatge under load. Cells sagging badly will have higher resistance and in low current draw situations they cope well but once they reach a tipping point the resistance has more of an affect and cell voltage crashes.
The cut out is LVC and will be about 30 - 32v, it only needs one cell group to hit LVC for power to trip /cut out.
 

Mike C

Finding my (electric) wheels
Jun 19, 2017
13
0
56
deeside
Hi, I have exactly the same issue with my BBS02 48v 750w. Do you know if there is anywhere you can get this type of battery load tested? I'm based in North Wales not far from Chester.
Cheers, Mike.
 

Gurnard

Pedelecer
Dec 30, 2015
36
5
53
OK finally got a new battery and that has fixed the issue.
Got a lovely little 7ah bottle battery (my commute is 1 hour round trip) weighs a bit less than 2kg.

But why do they always drill the mounts for a bottle cage battery that do not line up with standard bottle cage size. They are no-where near :)
 
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