bafang bbshd getting hot, excessive battery consumption

[CrossRoads]

Dunno if overheating is a common issue with the bbshd. Was taking it up a steep hill to a frien'ds house i often visit, which i have done plenty of times before with this bike and this time it was feeling underpowered, and it used 20% of the battery, about twice as much as it has before to make the same climb, and also the motor was quite hot to the touch at the top, like, not smelly or smokey, but could cook an egg on it. Outside temperature was a mellow 65 degrees farenheit. Also the power was noticably sluggish.

Almost new system installed 2 months ago. I thoutht these things were supposed to be rock solid? After letting it cool down the ride later the same day it was performing as usual. It's the 52v version. Does this mean there is something wrong with the system and i should be concerned or was it just overheating a bit and i need to take it easy? Is excessive power consumption / battery drain typical with an overheated motor?

 

[major masingil]

It is possible you were in too high of a gear while going up the hill. Do you know what gear you were in? Excessive heat is one of the worst things to happen on the motor. You definitely want to solve this one. On big hills you want to be in gears 1-3 ish. The faster you allow the motor to turn the better it is at not having heat build up.

Mine doesn't get that hot. It can get pretty warm but still touchable. I ride it on some pretty big hills

 

[CrossRoads]

Thanks, that's sound advice. Generally on a climb, i'm choosing the gear to match my prefered cycling cadence, what my legs want, not as low as possible for the motor, as i would with a hub motor. It's entirely possible i was not paying much attention and choosing a gear or two higher than I do typically. I'm new to mid-drives, so not trained in using them yet. It still felt like the affect was pretty dramatic.

 

[major masingil]

You just need to be aware that it can happen. It always helps to use those gears and leg muscles, lol. It's easy to forget about those on a BBSHD. I find myself peddling faster cadence when I want to maintain higher speeds. If I want the hill to be more like a regular bike, I turn the PAS down to the level that is basically a little more than enough juice to compensate for the effect the motor and battery have on the bike. Having it low power doesn't allow it to heat up very much, and keeping the rpms up is better for slower heat build up at higher speeds. You can still shift to higher gears while you're going up hills as long as you're willing to peddle enough to keep it in its power-band.

 

[Rawly Old]

Dunno if overheating is a common issue with the bbshd. Was taking it up a steep hill to a frien'ds house i often visit, which i have done plenty of times before with this bike and this time it was feeling underpowered, and it used 20% of the battery, about twice as much as it has before to make the same climb, and also the motor was quite hot to the touch at the top, like, not smelly or smokey, but could cook an egg on it. Outside temperature was a mellow 65 degrees farenheit. Also the power was noticably sluggish.

Almost new system installed 2 months ago. I thoutht these things were supposed to be rock solid? After letting it cool down the ride later the same day it was performing as usual. It's the 52v version. Does this mean there is something wrong with the system and i should be concerned or was it just overheating a bit and i need to take it easy? Is excessive power consumption / battery drain typical with an overheated motor?

Bracket too tight locking bearings?

 

[bigoilbob]

Dunno if overheating is a common issue with the bbshd. Was taking it up a steep hill to a frien'ds house i often visit, which i have done plenty of times before with this bike and this time it was feeling underpowered, and it used 20% of the battery, about twice as much as it has before to make the same climb, and also the motor was quite hot to the touch at the top, like, not smelly or smokey, but could cook an egg on it. Outside temperature was a mellow 65 degrees farenheit. Also the power was noticably sluggish.

Almost new system installed 2 months ago. I thoutht these things were supposed to be rock solid? After letting it cool down the ride later the same day it was performing as usual. It's the 52v version. Does this mean there is something wrong with the system and i should be concerned or was it just overheating a bit and i need to take it easy? Is excessive power consumption / battery drain typical with an overheated motor?

Does your motor have an overheat shut down?

My wife's BBS02 powered bike, with adjustable Enviolo* auto trans, stopped on the big hill around Pebble Beach. It was 2-3 minutes and it started up again. She was being lazy, with a 25 r/m pedal cadence and a 3 of 5 assistance level. When it clicked back on, she upped it to 45 and took the hill again. No problem.

I'm not intricate here, but if your motor has such a safety feature, and it's not hooked up.......

*Hey, Enviolo auto trans equipper, lose the phone app for changing pedal cadence/motor speed. It's about as convenient as the 10 year old NuVinci Developers kit I use on my converted 60's era Taco mini bike. To change cadence on it I have to plug my laptop into the control box and replace the excel based control program that's in there now. I have it the way I want it, but just sayin'. So, shell out the extra few bux to go back to the old electronic twist control that my wife has. Works like a dream, instantly.

 

[m@Robertson]

Everything @major masingil is telling you is spot on. This sounds very much like an issue caused by gearing. Its sort of the classic mistake made on mid drives. I put this list of do's and don'ts together and its one of the more visited pages on my site:

How To Ride a Mid Drive Ebike Without Breaking It

If you can ride a bicycle you already know how to ride a hub drive ebike. Not so a mid drive. Particularly a powerful one that can tear your chain apart. Fear not. The rules are simple.

talesontwowheels.com

The 'short version' of what to do is, and I quote:

Keep the motor spinning

I ride cargo bikes in an area where there are steep hills. At the bottom of a paved hill, my best practice is to go one cog *lower* than my preferred cadence. Maybe even two. Throw speed out the window as a consideration and let it go slow if necessary at some points. Then I pedal my way up at my preferred cadence on low PAS, which is my preference. As the slope changes I use my PAS selector to click assist up or down a notch at a time, which favors keeping my cadence versus my speed.

Essentially what I've done is substitute PAS selection for a derailleur shift, which has secondary benefits as shifting on a hill (regardless of whether a gear sensor is installed) with a mid drive in play is always sub-optimal. I set my gearing so it is low enough to never be an issue (bogging) at the bottom of the hill.

This would be tougher to do on a hill whose summit you can't see and/or you don't know.

Bracket to tight locking bearings?

Not an issue on a BBSHD. If anything, the tighter the better. I recommend 90 ft lbs on an installation of the inner lock ring (and use two inner rings together as a jam nut) which is WAY past the manufacturer spec but a proven good number.

 

[m@Robertson]

My wife's BBS02 powered bike, with adjustable Enviolo* auto trans, stopped on the big hill around Pebble Beach.

Hah I live in the same area (not inside the gates ... I'm in PG and range from PG to Monterey, Sand City and as far out as Marina). I went out to Laguna Seca yesterday to see what was happening at Sea Otter.

We have low hills here, but they make up for that by being pretty steep in some places. Definitely could stress a BBS02. Coming up from Monterey I have a 16% grade to get over unless I take the long way around via Spanish Bay.

 

[Rawly Old]

Everything @major masingil is telling you is spot on. This sounds very much like an issue caused by gearing. Its sort of the classic mistake made on mid drives. I put this list of do's and don'ts together and its one of the more visited pages on my site:

How To Ride a Mid Drive Ebike Without Breaking It

If you can ride a bicycle you already know how to ride a hub drive ebike. Not so a mid drive. Particularly a powerful one that can tear your chain apart. Fear not. The rules are simple.

talesontwowheels.com

The 'short version' of what to do is, and I quote:


I ride cargo bikes in an area where there are steep hills. At the bottom of a paved hill, my best practice is to go one cog *lower* than my preferred cadence. Maybe even two. Throw speed out the window as a consideration and let it go slow if necessary at some points. Then I pedal my way up at my preferred cadence on low PAS, which is my preference. As the slope changes I use my PAS selector to click assist up or down a notch at a time, which favors keeping my cadence versus my speed.

Essentially what I've done is substitute PAS selection for a derailleur shift, which has secondary benefits as shifting on a hill (regardless of whether a gear sensor is installed) with a mid drive in play is always sub-optimal. I set my gearing so it is low enough to never be an issue (bogging) at the bottom of the hill.

This would be tougher to do on a hill whose summit you can't see and/or you don't know.


Not an issue on a BBSHD. If anything, the tighter the better. I recommend 90 ft lbs on an installation of the inner lock ring (and use two inner rings together as a jam nut) which is WAY past the manufacturer spec but a proven good number.

That is not what one tuttorial warns; too much torque on the bracket will bind on the bearings,(bafang mid-drive). use torque wrench
& do not exceed recommended torque. Apparently this is a common issue.

 

[m@Robertson]

That is not what one tuttorial warns; too much torque on the bracket will bind on the bearings,(bafang mid-drive). use torque wrench
& do not exceed recommended torque. Apparently this is a common issue.

Thats not true.

Having 9 of them, all of which use 90 ft lbs (or 100) of torque to affix the motor, I can speak from some level of experience dating back to my first (bike is still in use) from 2017. Also being a member of a number of Bafang DIY groups, I have literally never heard of this problem, so no its not common.

If you understand how the attachment mechanism works, you'd be hard pressed to explain how binding is even possible. The axle assembly is not clamped on the bearings. The lock rings are simply nuts. They encircle the axle. They don't bind it down. Neither does the mounting plate.

Luna Cycle used to sell ebikes with BBSHDs pre-assembled on the bikes and they had an instructional video showing the use of an automotive torque wrench to apply 100 ft lbs of torque to their inner lock rings, stating they did that with all of their bikes to assure they never moved, along with an assertion that the threads can take it. I followed that for a few years myself although when I came up with the use of doubled inner lock rings as jam nuts, I backed that off to 90 ft lbs each and it has proven to be just fine.

The following during-assembly images come from this page, which is dedicated to pre-fitment. There is a separate installment (Assembly Day One, click on the Final Motor Assembly chapter) that you want to refer to for the actual final fitment:

How To Build An Ebike From Scratch: Tinkering

We crawl one step further: confirm as best we can that motor will fit, then buy and test-install it so we can take more measurements.

talesontwowheels.com

You can see the threads, and...

now the mounting plate (binds as much as a washer would) and the two stacked inner lock rings (i.e. nuts) which is not using the two M6 nuts yet since this is a test fit. If you want to see whats on the other side, there are photos of that as well. This particular installation uses a 3mm polymer spacer on that side.

I wrote articles like this specifically to combat this sort of misinformation. Mid drives have the reputation for reliability that they do chiefly because so many people wing it, don't have a guide that explains the do's and don'ts, and fail accordingly.

 

[m@Robertson]

Lets dispel this binding notion fully by looking at all the parts and explaining how each works. First of all, below is the mounting plate. its upside down to show the ridges that will face the bottom bracket. This plate goes between the frame and the mounting rings as a sort of washer. The visible ridges will dig into the bottom bracket metal - from the clamping force provided by the lock rings. It is these teeth that do the work of fixing the motor, but only in conjunction with the two M6 bolts which attach the mounting ring to the motor.

Here is the final assembly, with the mounting bolts attached to the mounting plate. These mounting bolts mate the mounting plate/washer to the motor, so if the washer can't move, the motor can't move either. Those two M6 bolts and the dug-in steel ridges are what keeps the motor from rotating/moving. This pic also shows a separate additional clamping mechanism (the hose clamps) that is a precautionary measure for motors subject to extreme use (i.e. singletrack drops). Not relevant here.

You can see the non drive side bearing around the squared-off spindle above. The lock ring is not clamping that bearing. The same goes for the drive side, where the secondary housing is what is taking the force independent of the spindle or the spindle's bearings (there's one inside, not on the outer edge and its sort of free-spinning and not subject to clamping. You can find pics of this on web sites that sell spare spindles/axles).