New Bafang Crank-Drives

[tomjasz]

Thanks Tomjasz.....However,it doesn't look like its offered for the 750w motor.

Check that may be just an oversite in the listings of the package.

 

[Rusty123]

I've got a 36v 350w unit. Can I install one of the replacement controllers that Paul (and others) are selling to convert to 500w (25 amp vs 18 amp)? Or will that overload/overheat the motor?

 

[astmacca]

I've got a 36v 350w unit. Can I install one of the replacement controllers that Paul (and others) are selling to convert to 500w (25 amp vs 18 amp)? Or will that overload/overheat the motor?

Not sure, but it appears they are NOT the same motors.

http://www.electricbike.com/bafang-bbso2-750w-mid-drive/

The 750W unit appeared to be the same physical size as the 350W unit, and my experience with exaggerated China-made performance claims made me skeptical of the 750W spec. However, I have recently been informed by a North American distributor that the motor is wound to a different Kv, so when it is run at 48V, it will spin at the same output RPMs as the 36V / 350W version.
This allows the mechanical-gear RPM-reduction to remain the same for both units, and they can also share many of the same housing and interface parts. More volts can add more power without significantly adding more heat, and it is the heat that has frequently proven to be the limiting factor on these smaller motors.
However, we do not live by volts alone. The North American distributor has verified that the stator on the 750W unit is 5mm wider, which allows for a slightly greater copper mass (it is roughly one pound heavier due to the wider steel stator and extra copper wire in the coils). This means that the BBS02 motor can handle more amps than the BBS01 motor before reaching saturation. As you can imagine, I was very pleased to learn this. Both units have built-in over-temperature protection circuits that will cut power before the unit would be damaged.

 

[Rusty123]

Sorry - I should have been more specific - I wasn't talking about installing a 48v controller (because the 48v motor is indeed different than the 36v motor), but rather, installing the 25 amp 36v (vice 18 amp 36v) controller. I'm thinking this involves an upgrade from 6 fet to 9 fet controller?

 

[hie2kolob]

I have been using the Italian 42T chain ring for about 275 miles now and am now experiencing some serious "chain suck". When it occurs, usually the pedals suddenly jam with an accompanying grinding sensation. What happens is that the front chain ring grabs the chain (the bottom portion) and pulls it up, jamming it into the underside of the right chain stay. In bad cases, the chain can get jammed between the chain ring and the frame becoming seriously stuck.

The soft aluminum teeth on the Italian ring show significant wear as you can see in the pics. There were definite wear lines that I gently removed with a file in my attempts to solve the problem, but to no avail it still sticks and jams. This problem completely stopped when I removed the Italian chain ring and installed the stock ring.



Has anyone else experienced this problem? Do you have any recommendations?

Thanks,
Jeff

 

[Samd]

I got a sh*t unit from BTN this week via aliexpress, and the controller is shagged on delivery. Error 30.
Same old bullsh*t story about customer paying the freight back in order to dodge testing before despatch. And there seems to be a new serial number ground into the case over the old one. Dodgy.

So I think I will wire it up direct to a 6 fet controller and remove the display.

Sent some sizing to the laser cutters for a 104 BCD Chainring adapter, should make a good little commuter.

 

[Kepler]

Sorry to hear you got a bad controller. Seeing it is just a 350W unit, wonder if one the little sinewave controllers will do the job? http://www.bmsbattery.com/controller/695-s06-250w-imitation-torque-square-wave-controller.html

 

[Samd]

Hey thats a nice idea Kep.
It's actually a loan bike I'm knocking up for a mate in Melb - I'm going to try to bury it behind the tin dutch style skirt-guard.
It's a bit more manly than my usual bike...
I'm kinda thinking this might be a good outcome anyway to avoid the usual BBS bunch of wires and display up on the very minimal handlebars.


I'll try it with the Ku63 square wave first. She lives in a flat area. Might actually be ok with just a pedelec sensor external and no throttle given the nice gentle ramp up on the Ku63.

I was going to trim the shunt back a bit anyway to go easy on the three speed hub at the back.

And I can always swap it out for a fixed controller / display unit down the track...

 

[astmacca]

Sent some sizing to the laser cutters for a 104 BCD Chainring adapter, should make a good little commuter.

Dont suppose you would be able to share that sizing info?? Thats something i'd like to get made up down the track a bit.

 

[Samd]

Well they'll be on my webshop soon if you want to save the trouble! Let me see how they turn out first...

 

[astmacca]

Cool. Will check there occasionally. I have a 500W kit in the mail that's going on my old MTB in the next couple of weeks. Have ordered the 46T chain ring, but am used to the 42T as the biggest option on my current bike and am not interested in going faster than i do now, just easier into headwinds and hills.

Will see how it goes when i actually get to use the kit, but may be looking for an option to put a 42T on. Saw the post a couple back about the Italian option and thats making me think a standard type of chainring that is relatively easily replaced may be th eway to go.

 

[Samd]

No problem sharing the file by the way, but I expect that my cost should be about $25 per adapter set, so probably not worth firing up the laser. Should fit in domestic postage too.

Probably wouldn't be hard to craft one up on a drill press though for a DIY solution...

 

[astmacca]

No problem sharing the file by the way, but I expect that my cost should be about $25 per adapter set, so probably not worth firing up the laser. Should fit in domestic postage too.

Probably wouldn't be hard to craft one up on a drill press though for a DIY solution...

If you can do it for somewhere around $25 with postage in Oz then i'd go with a laser cut from you rather than trying my own.

 

[Samd]

Let's see what I can do.

Opened up the 250w. Easier to work on than Aprilia middrives.

Nice central chassis with the motor bolting film one side, with Controller and clutch mech on the other side.


But Controller is fully potted. Wasn't expecting that.
Supplier is sending a new controller when china reopens in a week.

Original stamping blacked out. Hmmm.

 

[astmacca]

Yahoo! BBSO2 arrived today!!

Now awaiting battery.

 

[KINNINVIEKID]

Let's see what I can do.

Opened up the 250w. Easier to work on than Aprilia middrives.

Nice central chassis with the motor bolting film one side, with Controller and clutch mech on the other side.
View attachment 1

But Controller is fully potted. Wasn't expecting that.
Supplier is sending a new controller when china reopens in a week.

Original stamping blacked out. Hmmm.

Very dodgy Sam!
Looks like it was originally made in March then restamped as July.
Thats the problem with buying from China,sometimes you get crapped on!!

 

[tomjasz]

Who is the vendor please?

 

[fourbanger]

Sorry to jump in all willy nilly, but I have a deep yearning desire to know the answer to a question that has plagued... blah blah blah.

All else being equal, is there a legitimate reason one can see for opting for a 500w bbs02 @48V over the same @36V?

Cellman sells a 36V 16.5ah frame mount battery for $500.

Cellman sells a 47V 11ah frame mount battery for $450

The differences in Wh are 594 vs. 517 respectively, using the same cell technology.

It appears that $50 buys another 77wh.

Am I missing anything here?

Thanks as always,

V.

 

[Kepler]

It would seem the 36V pack is the best bang for buck providing the cells are the same. The 36V pack would need 60 cells (10S6P) and the 47V pack 52 cells (13S4P). So $50 gives you an extra 8 cells which indeed is a bargain.

The disadvantage of the 36V setup is a lower cadence capability and as such a lower possible top speed. If you are happy with a max speed of around 35kph, I think the 36V system is a good choice.

 

[fourbanger]

But might said cadence lowering AND the top speed limiting factors be offset *if* the motor was wound to an appropriate Kv to compensate?

[EDIT]

For the 12v lacking, I mean..

 

[Kepler]

BBS01 is rated at 80 RPM @ 36V
BBS02 is rated at 110 RPM @ 48V

There was speculation that they were wound for different speeds however the spec would suggest the winds are similar

 

[tomjasz]

If you are happy with a max speed of around 35kph, I think the 36V system is a good choice.

FWIW I get 25 miles full throttle rides, 100kg rider with the 13.8AH EM3ev 36V. Solid 35kph over half the charge.

 

[jkbrigman]

If you are happy with a max speed of around 35kph, I think the 36V system is a good choice.

FWIW I get 25 miles full throttle rides, 100kg rider with the 13.8AH EM3ev 36V. Solid 35kph over half the charge.

Tom, your comments are awesome. Makes me insanely curious what a BBS02 could do with 50v 20Ah, or a BBS01 with 36V20Ah.

Remember: the cool thing about staying low-voltage and upping the Ah is that you can get a higher-speed charger and ram current into the pack faster: if each cell can only charge at 1C, then every parallel leg adds another 1C charge rate.

In the case of LiPo bricks that can charge at 1C=5A, three in parallel allow 15A charging and four allow 20A charging. If you're using power at, say, a 5 amp rate and charging 4 times faster, NOW you're talkin!

It's GREAT to me to see conversations about range and efficiency. You see it so infrequently here on the Big E-S!

 

[tomjasz]

If you are happy with a max speed of around 35kph, I think the 36V system is a good choice.

FWIW I get 25 miles full throttle rides, 100kg rider with the 13.8AH EM3ev 36V. Solid 35kph over half the charge.

Tom, your comments are awesome. Makes me insanely curious what a BBS02 could do with 50v 20Ah, or a BBS01 with 36V20Ah.

Remember: the cool thing about staying low-voltage and upping the Ah is that you can get a higher-speed charger and ram current into the pack faster: if each cell can only charge at 1C, then every parallel leg adds another 1C charge rate.

In the case of LiPo bricks that can charge at 1C=5A, three in parallel allow 15A charging and four allow 20A charging. If you're using power at, say, a 5 amp rate and charging 4 times faster, NOW you're talkin!

It's GREAT to me to see conversations about range and efficiency. You see it so infrequently here on the Big E-S!

I understand that the BMS used limits the charge speed. New terms for me but both packs I have limit the charge to 3Ah(I think), chargers rated at 2.5Ah are supplied. I was disappointed but apparently no way round the issue. At least none for the uninitiated. I wish installing a CA on my system were more easier and understandable. I've a long protracted path I'm afraid.

 

[Samd]

Who is the vendor please?

Haha, sorry for the delay but I thought youd figure it out. See the red text below in my signature? :lol: