New Bafang Crank-Drives

[geofft]

Thanks, having once pulled some of my lipo's down to well under 2V (down to range optimism on my part...) I think I'll have to rig up something similar.

The lipo's seemed to survive their workout, I haven't noticed any detrimental effects since (yet..!).

 

[Fantomas]

What is the maximum voltage for 36V controller?
Could I use 2 x 6s li-po to 36V controller?
Thanks

 

[dirkdiggler]

I know you can do that with a voltage alarm. My controller shuts down at the right time for me. I want to be able to look at the display to see how much further I can ride without the battery running out. I don't want an alarm going off telling me that I have no battery and still miles from home. I need to know that its time to turn around. I'm using my BBS for single track mountain biking where I have options to keep riding or turn back. So battery management is crucial. I've been stuck before thinking I had a bunch of juice left and my legs just don't get the bike uphill like the motor does. I either find myself with too much or little battery left when I get home. Its hard to judge what I'll need battery wise, because it depends on my mood and how fast I'm wanting to go. Also sometimes I'm just out to enjoy the ride, but change my mind and want to pass those lycras. Stinks when they pass me later on because my battery ran out!

 

[tomjasz]

What is the maximum voltage for 36V controller?
Could I use 2 x 6s li-po to 36V controller?
Thanks

I'm a little confused, as always, but I'm trying to sort it. Since the op is asking...

A 6S pack is only 22.2 volts. Isn't the intended output nearer the range of the controller. In other words don't I want nearer 36V to make everything near correct? Since the pack I have for example is a 36V 18650 with top voltage 42V Wouldn't two packs in parallel or 12s2p, be the correct config for a 36V 350W BBS01? Alarmed to stop at 36V? Or is 44V to high?

Struggling...

 

[teslanv]

I think 12S may be a bit high. Fully, charged to 4.2V per cell, that works out to 50.4 Volts.

10S is the right voltage for the "36V" BBS01

 

[dusan]

For sure, it's 10s or even better 2x5s.
Cheaper charger, possible to form battery shape and in case of one cell failure, you need to change only one pack.

 

[tomjasz]

For sure, it's 10s or even better 2x5s.
Cheaper charger, possible to form battery shape and in case of one cell failure, you need to change only one pack.

Thanks..

I think 12S may be a bit high. Fully, charged to 4.2V per cell, that works out to 50.4 Volts.

10S is the right voltage for the "36V" BBS01

Got it! Thanks!
I'm maybe finally getting this...I look at the highest charge the cell is rated for? So 42V for the 18650. Do all 18650 cells rate at 4.2 max?

 

[parabellum]

There are few 4.35V rated, but I would not charge them that far.

 

[opperpanter]

What would be the most efficient rpm range to be using with the 48V750?
Max is 112rpm, so keep it between 70 and 100?

I am trying to decide the gearing to use with my new MTB build.

At what rpm will the motor start having decent torque/power? Wih the big front chain, I might need to find a compromise.

 

[KINNINVIEKID]

My Cannondale 29er has a 46T chainring and 34T-11T cassette and will pull my 235lbs up the 17% hills round here no problem.
I also ride the local forest trails and it copes perfectly.
I am very unfit and currently average 21Wh/m.
I decided to check my cadence on a flat road in 7th gear(out of 8) and was amazed to find I was pedalling at 148 rpm!!

I find the motor pulls from low revs ok and unlike a hub its easy to keep the power there by simply using the gears.
have a 44T as well but have not needed it yet but if we get a good lot of snow I may put it on then.
I currently run at 44.4V (BBS02-750) and will be going up to 51.8 shortly.

 

[Russell]

My Cannondale 29er has a 46T chainring and 34T-11T cassette and will pull my 235lbs up the 17% hills round here no problem.
I also ride the local forest trails and it copes perfectly.
I am very unfit and currently average 21Wh/m.
I decided to check my cadence on a flat road in 7th gear(out of 8) and was amazed to find I was pedalling at 148 rpm!!

Assuming your tires have a rolling diameter of 28.5" and your 7th gear is 12T a crank speed of 148 RPM calculates to a bike speed of 48 mph. For a 46/13 combo 148 RPM is 44.4 mph. With a 46/28 combo it calculates to 20.6 mph.

I spin in the mid-90 RPM range for hours and for short bursts can get up around 120 RPM but that is not sustainable.

-R

 

[Samd]

any you off road riders fave your magnet slide out of position?

I got the er21, was surprised you can still ride the bike with the display like that, everything works just don't the battery level...

Kind of good to discover if anyone knows of a way to do away with the display would be even better. Will see if the display stays on with keeping the magnet infront of the sensor just reading zero all the time....

I sure do Boz, especially on a bike that also has a hub. I usually add a second small magnet to stop the original one failing to register after small rotations, and use a bit of loctite on both to keep it all in place. I've had lots of customers et in touch several months into riding one thinking theor drive has failed.

 

[opperpanter]

My Cannondale 29er has a 46T chainring and 34T-11T cassette and will pull my 235lbs up the 17% hills round here no problem.
I also ride the local forest trails and it copes perfectly.
I am very unfit and currently average 21Wh/m.
I decided to check my cadence on a flat road in 7th gear(out of 8) and was amazed to find I was pedalling at 148 rpm!!

I find the motor pulls from low revs ok and unlike a hub its easy to keep the power there by simply using the gears.
have a 44T as well but have not needed it yet but if we get a good lot of snow I may put it on then.
I currently run at 44.4V (BBS02-750) and will be going up to 51.8 shortly.

Thanks. I guess I should try it first (bbs02 with 44t and 11-30 cassette) before worrying .
Or maybe order spider adapter and some 38t and 32t chain rings just in case

Please note I will be using throttle only (no pedaling).

 

[tomjasz]

I'm trying to reach, but without success. What is the operating RPM of the BBS01 36V at or near full throttle with a rider. Real world anyone know? (care)

 

[Arvicola Terrestris]

I'm trying to reach, but without success. What is the operating RPM of the BBS01 36V at or near full throttle with a rider. Real world anyone know? (care)

The most "real world" I can give you is these measurements Bafang have made:



On this curve you can see that the operating RPM of the BBS01 36V at or near full throttle is 85rpm.
Or thats what i read it to be

 

[tomjasz]

Thanks, lin to where you found this, if it's handy.

 

[Arvicola Terrestris]

Thanks, lin to where you found this, if it's handy.

http://www.tnabattery-ebike.com/?bafang-BBS01-Crank-drive-motor-p199.html

 

[tomjasz]

Perfect! Again thanks! Oh and thanks for that great thread on the shaft and bearings. I have a set ordered for my parts backup. Here in salt covered winter streets you mod may be a project for me!

 

[tomjasz]

Have you ordered from that supplier?

 

[John Bozi]

Careful with forgetting the alarms as I did and lost .1v a cell on cell 1,2,3 so bit of a difference and the chargers didnt like dealing with it.

I ended up using epoxy glue and after many very rough rides where everything else has failed the magnet is in place.

You can see my drive train and how rough I ride here:

http://www.youtube.com/playlist?list=PLzqojlpNeKR3t_VglNJXlBRmy_6rz9GuX

 

[Arvicola Terrestris]

Have you ordered from that supplier?

No, I bought mine from Amy (can't remember the company). These Motor Characteristic Diagrams are worth gold if anybody want to optimize their bicycle gearing. But the diagrams are scattered over the Internet, weird that Bafang isn't doing more on suppling these information to there audience (us).

Here is the diagram for the 48v 500w model.
View attachment Motor Characteristic curve 3.pdf

And for the 36v 250w motor:


And a blueprint:
View attachment Bafang BBS01 250W Tecnical drawing.pdf

And a data sheet:
View attachment Bafang Data.pdf

EDIT: uploaded a better Diagram as PDF, should be better to view
EDIT: uploaded the diagram for the 36v 250w motor so they are all in one post

 

[opperpanter]

Have you ordered from that supplier?

No, I bought mine from Amy (can't remember the company). These Motor Characteristic Diagrams are worth gold if anybody want to optimize their bicycle gearing. But the diagrams are scattered over the Internet, weird that Bafang isn't doing more on suppling these information to there audience (us).

Here is the diagram for the 48v 750w model.

Thanks, really helpful!
The diagram is a bit hard to read, here's a summary:

Max efficiency of 82% at 106rpm, 10.37Amps, 37Nm torque.
Max torque 90Nm at 59rpm, 17.08Amps.
Max power out 638W at 88.7rpm, 16.88Amps.

Looking at the graph, the efficiency stays above 80% between ~95rpm and ~112rpm.
Even at 60rpm it's still almost 70%.

Since the max amp draw is around 17-18Amps, I guess this is the 500W version?

How would the data/curve look for 750W?

 

[Arvicola Terrestris]

Have you ordered from that supplier?

No, I bought mine from Amy (can't remember the company). These Motor Characteristic Diagrams are worth gold if anybody want to optimize their bicycle gearing. But the diagrams are scattered over the Internet, weird that Bafang isn't doing more on suppling these information to there audience (us).

Here is the diagram for the 48v 750w model.

Thanks, really helpful!
The diagram is a bit hard to read, here's a summary:

Max efficiency of 82% at 106rpm, 10.37Amps, 37Nm torque.
Max torque 90Nm at 59rpm, 17.08Amps.
Max power out 638W at 88.7rpm, 16.88Amps.

Looking at the graph, the efficiency stays above 80% between ~95rpm and ~112rpm.
Even at 60rpm it's still almost 70%.

Since the max amp draw is around 17-18Amps, I guess this is the 500W version?

How would the data/curve look for 750W?

On the right side of the diagram there is a summary of max torque, efficiency, speed and power.

 

[opperpanter]

The kits I got from Paul/em3ev came was the C965A display. This display can have maximum speed limit set to 99.9km/h.
Will post manual later.

 

[Warren]

opperpanter,

"Since the max amp draw is around 17-18 Amps, I guess this is the 500W version? How would the data/curve look for 750W?'

It would look exactly the same. The only difference in the two kits is the max amp setting in the controller. These curves are typical of electric motors. About 80% of no load speed is most efficient, about 50% of no load is most torque. Having the controller allow 25 amps will mean you can generate more power/watts, but at the expense of lower efficiency/more heat when you bog it down in too high a gear.

To efficiently get more power, you would need a controller which allows higher voltage. But then you would need to be able to change the gearing between the motor and cranks, if you want to maintain a useable cadence to do actual pedal assist.