Bafang BBS02 Stutter

[robwalley]

First ride this year (shoot me) since November 2017 with fully charged battery and no other changes, but stutters on the steepest hill at the 100% assist levels. Not low voltage (fully charged and I know what that feels like). I use the BafangConfigTool app, but like I said no changes since last year, I'll check settings, but odd, doesn't appear to be on throttle, just the assist (I think).

 

[robwalley]

Definitely PAS only, doesn't happen on throttle and only at the higher draws > 90% power, 650w+. Happens mostly but not always and may be getting worse. No error codes or any logs. Wonder if it's a battery issue, will charge again and test.

 

[tommie]

Possibly a cell gone faulty after the long lay off?

 

[robwalley]

Possibly a cell gone faulty after the long lay off?

Charged every couple of months, admittedly to 100%, just refuses to drain over the winter period. However why doesn't it do this on throttle (may not pull quite the same wattage)

 

[Nealh]

Throttle should place more direct load on battery then pas, so should rule out any duff cell issue.
If all is well with throttle use Could be the pas magnet has broken/snapped also worth checking PAS settings. Have a look at the pas connector for damp ingress.

 

[robwalley]

Throttle should place more direct load on battery then pas, so should rule out any duff cell issue.
If all is well with throttle use Could be the pas magnet has broken/snapped also worth checking PAS settings. Have a look at the pas connector for damp ingress.

What I meant was according to my colour display, full throttle is pulling less wattage than Peak PAS. PAS magnet issues should affect the whole range, not just peak draw? I have tweaked and lowered the PAS settings to ensure it was still happening - it is. I know a couple of 36volters in Cheltenham, I may borrow a battery to dismiss that suspect from ongoing enquiries.

 

[robwalley]

My throttle is set to 38v max, probably why it isn't pulling the current the PAS is. I'll change this to max and test. If on both then probably battery cell issue.

 

[robwalley]

New battery (which I was buying anyway 36v 17.4ah from eclipse) and no difference, still juddering when pulling 80%+ on PAS. Cannot make it do this with throttle.

 

[tommie]

strange one,

that 3-button switch, it wouldnt be shorting out internally??

connections in the loom?

 

[minexplorer]

Hmm.When you say stutter do you mean power cutting in and out? I had an issue with PAS on a bbs01 that got slowly worse too.Where under heaviest load, low speed.Such as hills and starting off. The power would cut off and a moment later back on repeatedly .It was worse if i was in higher gears for those situations than optimal and stopped when the load reduced.Ie dropped gear /speed increased.
Using throttle perfectly fine, just when using PAS. When disconnecting the throttle the problem went away.Eventually Eclipse bikes tested the controller on one of their bikes and got the same issue. Sent me a new controller under the warrenty.It was a very bissare and took a long time to get to the bottom of. Seemed to have started after being out in rain few times.Could storing bike some time in damp conditions ? cause a similar issue i wonder.

 

[GLJoe]

First ride this year (shoot me) ... stutters on the steepest hill at the 100% assist levels.

Bang!
Since you've tried another battery, I'd be checking that you haven't picked up some additional resistance somewhere in the power lead connections. Maybe come light oxidization somewhere causing a bit of a voltage drop at the highest power settings.

 

[Deleted member 4366]

Bang!
Since you've tried another battery, I'd be checking that you haven't picked up some additional resistance somewhere in the power lead connections. Maybe come light oxidization somewhere causing a bit of a voltage drop at the highest power settings.

Good point. I had one with connectors so loose that they could just fall apart.

 

[GLJoe]

Good point. I had one with connectors so loose that they could just fall apart.

Yes. One of our bikes suffered a damaged power cable. The replacement wasn't quite as thick as the original, and while it worked fine most of the time, at the highest power, it would cause the bike to shudder! Very bizarre.

 

[robwalley]

The new battery has a different mount, so the same power cable from the motor was used, the only change is the 4 inches or so of cable from the battery mount connectors to a terminal block inside the mount (same method as previously) and the issue is on both old and new batteries. I intend to strip bike and clean next week, so was going to check all cables including inside the motor casing. I also have V2 of Eggrider just arrived which replaces the display and the four button control, so I check that area too and I will remove the throttle to check also (every test involves riding a couple of miles to a very steep 20% hill).

 

[robwalley]

strange one,

that 3-button switch, it wouldnt be shorting out internally??

connections in the loom?

Just got the new Eggrider V2 which replaces the display and buttons, so will check the switch. My boom is a custom made one of specific length and no brake connectors ( found a company a couple of years ago doing this ) has been brilliant so far.

 

[robwalley]

Hmm.When you say stutter do you mean power cutting in and out? I had an issue with PAS on a bbs01 that got slowly worse too.Where under heaviest load, low speed.Such as hills and starting off. The power would cut off and a moment later back on repeatedly .It was worse if i was in higher gears for those situations than optimal and stopped when the load reduced.Ie dropped gear /speed increased.
Using throttle perfectly fine, just when using PAS. When disconnecting the throttle the problem went away.Eventually Eclipse bikes tested the controller on one of their bikes and got the same issue. Sent me a new controller under the warrenty.It was a very bissare and took a long time to get to the bottom of. Seemed to have started after being out in rain few times.Could storing bike some time in damp conditions ? cause a similar issue i wonder.

Yes, PAS cutting in and out a few times per second causing a juddering effect, seems too even to be cabling, more like controller, still testing. I don't get out enough to see if it's getting worse yet.

 

[Fordulike]

Yes, PAS cutting in and out a few times per second causing a juddering effect, seems too even to be cabling, more like controller, still testing. I don't get out enough to see if it's getting worse yet.

I have read a few reports of owners having similar problems and upon opening the drive unit, finding the PAS sensor disc broken apart.

My own experience on this, is when checking inside the unit to grease the nylon gear, I found mine to be cracked. Mine doesn't cause any PAS issues though, but it'll be one of the places I'll check if I do.

 

[tommie]

Just got the new Eggrider V2 which replaces the display and buttons, so will check the switch.

Maybe you can do a review on this?

Very interested in getting one.

 

[robwalley]

I have read a few reports of owners having similar problems and upon opening the drive unit, finding the PAS sensor disc broken apart.

My own experience on this, is when checking inside the unit to grease the nylon gear, I found mine to be cracked. Mine doesn't cause any PAS issues though, but it'll be one of the places I'll check if I do.

Thanks, I'll check this soon, sounds the most likely, except the bafang is not any clever torque sensor, just a cadence sensor I understand, so if cracked or broken why logically does it only affect high amps, not high cadence.

 

[robwalley]

Maybe you can do a review on this?

Very interested in getting one.

Will do. I still haven't downloaded the blutooth app yet which connect to it, but once done can program from phone on the go just like the BafangConfigTool windows software along with usb/serial cable. I am also sure Bafang have their own similar device and bluetooth app coming out, but probably without the programming ability.