New Bafang Crank-Drives

[tahustvedt]

It was an unreasonable point to make. The claim was made that I was confused about my understanding of torque because I said torque is a function of current.

Never mind. Back to Bafanging.

 

[tahustvedt]

I received some high quality 3.3 mm thick 8 conductor cable to make a new harness. I never liked the bulky original harness. I'll post pictures once I have soldered it all together. Am still waiting for the connectors for the head unit and brake switches. I'm going to use a simple header strip with 2.54 mm pitch.

 

[Kepler]

It was an unreasonable point to make. The claim was made that I was confused about my understanding of torque because I said torque is a function of current.

Never mind. Back to Bafanging.

Hang on. Let's not leave it hanging there

It's not that I disagree that torque is a function of current, its the fact that you have dismissed that volts are also a function of torque and as such would have an effect on the results of the test. l believe this is the point RP3 was making.

I can't believe I am arguing about this You are right. Back to Bafanging

 

[tahustvedt]

Increasing voltage would increase current if this was an unregulated motor. But how much the torque increases depends on how the efficiency changes. A DC motor connected directly to a battery for example would do that. My Bafang is current limited to 15 A, so any state of charge on the battery will always max out at 15 A. I have not seen the current go past 14,7 A on the Watt's Up, but I don't watch it constantly since it's behind me.

 

[Ken Taylor]

My understanding is that if you left the current the same but doubled the voltage, theoretically you will double the motor speed and double the torque.

You will double the speed but torque is unchanged, i.e. not doubled.

 

[nioko]

I know there are some who use the 750w unit on 12s... Would you do this again? What top speeds are you getting? My problem is, i have several chargers capable of max. 6s, and I want to build a pack that I can charge in one step (charging as 6s8p, discharging as 12s4p).

 

[teslanv]

I know there are some who use the 750w unit on 12s... Would you do this again? What top speeds are you getting? My problem is, i have several chargers capable of max. 6s, and I want to build a pack that I can charge in one step (charging as 6s8p, discharging as 12s4p).

12S works quite well on the BBS02 750W kit. I run mine with 4S hardcase LiPo packs, for a total of 12S, 5Ah.

Top speed will depend on your bikes gearing & wheel size.

Unloaded crank speed at 50V is right around 120 RPM.

With 48T front & 11T Rear sprockets, and 26" Wheel diameter, that translates to an unloaded speed of 42 mph. Real world on the flat is more like 32 mph.

60V gives a noticeable RPM/power boost over 12S. If I were to do a different battery set-up, I'd go with (3) 5S packs for 15S Total, Charge to a max of 4.1V/cell or 61.5V total.

14S, Like the Triangle packs em3ev.com sells, are also a great option, as long as you get one that can handle 25A continuous. That would be 58.8V max.

 

[mclark999]

Can some one post a picture of the new 750w 25 amp serial number plate when they get one?

 

[nioko]

With 48T front & 11T Rear sprockets, and 26" Wheel diameter, that translates to an unloaded speed of 42 mph. Real world on the flat is more like 32 mph.

Yes, 15s would be the other option, but as I will be running this thing as a daily commuter, I'd prefer not to be at any of the limits. I'll ride it hard, and often..

32mph sounds very good to me, although, I'll be running Li-Ion (out of power tools), I'm pretty sure they will sag more than your Lipo's.
Is that using PAS or throttle? I'll be using PAS only.

 

[teslanv]

32 mph requires WOT at the full 25A. Using the highest PAS setting, you'll only get around 25-28 mph on the flat. A more comfortable riding style for me using PAS is level 5 of 9 (about 50%) and it gets me into the low 20 mph range.

 

[BRS]

Hello Forum Members,

I just signed onto the forum yesterday for the first time. Stayed up late reading through all 114 pages of these posts. OK, I didn't read everything. What brought me to the forum is a need for the 130 BCD spider as I need to go to a larger chainring. Seems there are three available. One from Eride, one from crossbreak, and one from <http://california-ebike.com/product/ba130-bafang-chainring-adapter/>. Does any one know if there are any significant differences?

Great forum BTW. Lots of good technical information. I'm definitely looking into reprogramming my controller, adding a "shift-button", and trading my throttle for a "boost-button". It's hard not to modify and tinker with these things.

Here are a few pics of my ride:
:HP Velotechnik Grasshopper FX
:bafang 750W
:20" Wheels
:Rohloff with 16T sprocket (not pictured)

 

[Rassy]

Welcome to the forum BRS. It was nice to see the pictures of the Bafang mounted on the boom of your recumbent. I've been thinking that my next build will a FS tadpole with a Bafang mounted on the boom. It would look about the same as yours.

 

[hie2kolob]

Hi, I would like to first thank those that have contributed to the thread! As I read over much of the content I have found some great information.

I will be purchasing the Bafang BBS02 48V 750W Mid-Drive kit soon and need some advise. Originally I thought I would use an older Cannondale or Specialized Rock Hopper I have on hand. Both are over 12 years old without any suspension. However from what I have read it might be best to start with a newer bike. I average about 120 miles a week on my non electric road bike and I will be using this bike primarily for off-road dirt elevation rides. So here are my questions:

1- If I use one of the bikes I already have are they fully compatible and would you advise any sprocket change or modification?
2- What would be a good solid used Mt Bike to buy with suspension that is compatible?
3- Where is the best place to buy the Bafang BBS02 48V 750W mid-drive kit (best price with 2 weeks or less shipping)?

I have some experience with LIPO batteries from Hobby City and it appears that this might give me the "best bang for my buck."

4- What are your feelings about using LIPO's and are there any drawbacks?
5- If I use LIPO's what is the best battery combination with this 48V 750W mid-drive?

Thanks again for all your info!
Jeff

 

[BRS]

Jeff,
I got mine from em3ev.com. The fellow who seems to handle the sales department is Paul, a Brit working for them in China. Service and speed of delivery was surprisingly good and fast (to Washington State, USA). They use a 50v battery which can be charged at either 53.3 or 58.? for max range. I thought their battery price was quite fair, so look into what they have. Plus if you use their battery it might be easier to get warrentee service if there is an issue with the motor than would be if you built your own battery.

The bafang fits 68mm bottom brackets. It's not made to be used on a recumbent but worked out well for me after lengthening two wires. Should be no problem on your Rockhopper. As to getting another bike, I'd say if you would have gotten a different bike even if you were not going electric then I'd say Do-it. On the other hand. You can put the bafang on what you now have then move it later if you think you need springs. It's not a big deal to install once you have the tools to remove the BB. If I remember correctly the Rockhoper has non suspended fork. That would be an easy and reasonable upgrade to the bike instead of replacing it.

-Brock

Question to all - I've seen a lot of discussion about top speed. Providing you are not restricted by laws (read into that what you want), and don't need the speed meter on the bafang, you could just set the wheel size to 16" (minimum). If you try it (wear a helmet and full leathers) let us know how it works out. Should make a big difference for those of you with larger diameter wheels.

 

[savaoaknyc]

i have posted the same question in the other thread , but here again.

what is the minimum cut off voltage of bbs02 or bbs01?Can i set the minimum cut off at 2.8v per cell, so in case of bbs02 it will be 36.4v and with bbs01 28v??
Any information about this???

 

[amigafan2003]

i have posted the same question in the other thread , but here again.

what is the minimum cut off voltage of bbs02 or bbs01?Can i set the minimum cut off at 2.8v per cell, so in case of bbs02 it will be 36.4v and with bbs01 28v??
Any information about this???

I'll check in the software. I know the highest is 43v but I don't know the lowest.

 

[savaoaknyc]

i have posted the same question in the other thread , but here again.

what is the minimum cut off voltage of bbs02 or bbs01?Can i set the minimum cut off at 2.8v per cell, so in case of bbs02 it will be 36.4v and with bbs01 28v??
Any information about this???

I'll check in the software. I know the highest is 43v but I don't know the lowest.

Thx, that would be great.I was thinking to make a pack out of ncr 18650bd 3200mah cells, but if the minumum cut of voltage is 41 or 40 that would make around 3.0v at cell level.The discharge curves of the bd cells show around 2.8ah at 3v, which for me personally doesn't make any sense to buy this expensive cell, if i can't squeez at least 3.0ah.
In this situation the perfect cell would be the 2.9 ncr pf or samsung 29e, you get around 2.7ah at 3v.Even the lg d1 would be candidate, but it must be used only under 1.5c because of the heat.At 3.1v the lg gives around 2.8-2.9ah at 1c.

 

[free-trade]

2- What would be a good solid used Mt Bike to buy with suspension that is compatible?

Yesterday I removed the cranks and bottom bracket of my Specialized Stumpjumper FSR (2007) and checked if there is enough space for the BBS02. Looks every good.
The bottom bracket is 73mm, but many write here that this is not a problem.
Maybe you could modify the cassette to get a better chain line.
I don't know how much money you want to spend ...I ride this bike since 7 years and never had any problems. Very solid and not too heavy(13kg)

Greetings,
Andi

 

[free-trade]

Ah,as I had removed the bottom bracket yesterday, I wondered whether the convolution(thread turn- sorry, I don't know the right word. I hope you know what I mean.) in the frame(BB) get crushed by the pressure at the BBS02 assemble?
you can remove the motor and reassemble the bottom bracket without any problems??

greetings,
Andi

 

[tahustvedt]

What's up with this thing? The link title says "Bafang", but that doesn't necessarilly mean anything as these aliexpress listings can be all over the place in descriptive accuracy, but the connectors are similar to our BBS units. Is this a new model?

http://www.aliexpress.com/item/C961-display-LCD-2013-Newest-crank-mid-motor-36v-350w-bafang-brushless-geared-crank-drives-motor/1386562025.html

 

[Warren]

Jeff,

"I got mine from em3ev.com. The fellow who seems to handle the sales department is Paul, a Brit working for them in China."

Paul is "them." Or at least he was until recently. He now has some help.

 

[tomjasz]

What's up with this thing? The link title says "Bafang", but that doesn't necessarilly mean anything as these aliexpress listings can be all over the place in descriptive accuracy, but the connectors are similar to our BBS units. Is this a new model?

http://www.aliexpress.com/item/C961-display-LCD-2013-Newest-crank-mid-motor-36v-350w-bafang-brushless-geared-crank-drives-motor/1386562025.html

Not referred to as Bafang, 8Fun, or BBS0x. China sure is quick to respond to the market with a copy...

 

[free-trade]

What's up with this thing? The link title says "Bafang", but that doesn't necessarilly mean anything as these aliexpress listings can be all over the place in descriptive accuracy, but the connectors are similar to our BBS units. Is this a new model?

http://www.aliexpress.com/item/C961-display-LCD-2013-Newest-crank-mid-motor-36v-350w-bafang-brushless-geared-crank-drives-motor/1386562025.html

I don't think that this is a new bafang model. It seems to be a reproduction or something like that.
I don't know this engine, but when I look at the motor and the gearbox on the photos, it looks even wider than a BBS02 to me and the chainline appears to be greater and thus the chainring will be further to the right.
Maybe they have fixed this with chainring(cranked), because it is also very large (48 teeth, I counted them ).
I would prefer a Bafang BBS0x, many people have tested it until now and it seems to be quiet solid.

Edit: tomjasz was faster, I had a good look at the pictures before I typed my answer

 

[tahustvedt]

Not referred to as Bafang, 8Fun, or BBS0x. China sure is quick to respond to the market with a copy...

Check out the address bar: "C961-display-LCD-2013-Newest-crank-mid-motor-36v-350w-bafang-brushless-geared-crank-drives-motor" But that's the only place.

I don't think that this is a new bafang model. It seems to be a reproduction or something like that.
I don't know this engine, but when I look at the motor and the gearbox on the photos, it looks even wider than a BBS02 to me and the chainline appears to be greater and thus the chainring will be further to the right.
Maybe they have fixed this with chainring(cranked), because it is also very large (48 teeth, I counted them ).
I would prefer a Bafang BBS0x, many people have tested it until now and it seems to be quiet solid.

Edit: tomjasz was faster, I had a good look at the pictures before I typed my answer

The chainwheel looks like it has more dish than the Bafang chainwheel. Maybe it's a good chainwheel to use on the Bafang BBS to bring the chainline more towards the ideal if it can be bought separately.

 

[hie2kolob]

The 48V 750W Mid-Drive Motor Conversion Kit on conhismotor.com is not referred to as Bafang, 8Fun, or BBS0x either.

http://conhismotor.com/ProductShow.asp?id=431

Yet there have been those that have purchased and posted positive reviews on this thread. Do you think that these are made by Bafang?