New Bafang Crank-Drives

wheebikes,

I recently saw this video of someone who dropped two regular 9V batteries in the trash- the terminals touched and started a fire that just about took the whole house down. After my experience with flaming batteries I'm taking lot's of precautions and probably going a little over board. That being said- I think the batteries you pointed out are only slightly less safe than the batteries in your laptop, as they have more stored energy. They are regular Samsung and Panasonic Cells just like a laptop. They have load, charge and balance protection from the BMS, but no mention of thermal protection. I'm fairly sure laptops have thermal protection. I bet most people would consider them safe to charge indoors. But I'm not taking that chance again. I think my wife might just divorce me if I put the family at risk a second time- not even with a 9V battery.

The batteries I had were totally different and the system I was using was much less sophisticated.
 
Gotcha.

One other question - and maybe this is silly - but would a mid drive be better or worse than a small geared hub for a single-speed bike?
 
thetimp said:
m4s73r said:
A triple chain wheel adapter is what this really needs. It may have been said already but what length are the cranks and will any crank work?
Click to expand...

Cranks are 170mm. The problem is the chainring is separate from the right crank arm, but if you can find two individual crank arms (or tap out a left one to fit a right pedal), then you're good. It's a square taper spindle.
Click to expand...

http://www.utahtrikes.com/PROD-213.html

Something like this is what your talking about?
 
mwkeefer said:
amigafan2003 said:
Greenbike kit now have the 48v750w system.

http://www.greenbikekit.com/index.php/bafang-8fun-mid-crank-driving-bbs-02-kit-48v-750w-central-driven-motor-kit.html

How easy is it to overide the 25km/h speed limit?
Click to expand...

It's simple, get the kit and by the time you have it... Ill have posted a FULL technical breakdown with mods and all :)
:roll: I'm even working at reverse engineering the CPU and EEPROM to decode the communications protocol and offer a open source software package for changing the settings...

Be patient :)
Mike
Click to expand...

after read all posts dont found nothing after (about promises) on this post..Or i miss something: any progress?: :?:
 
CellBalance said:
Does anyone know of a Bafang parts supplier for things like C961 displays, speed sensor mounts -my old one broke (also upgraded recently I'm told), or harnesses?
Click to expand...
BBS harness for €29
http://www.alcedoitalia.it/shop/categoria-prodotto/componenti-kit/page/4/
 
Does anyone know how much torque these things apply to the cranks at full power? How would one go about calculating that? I suppose it could be very roughly approximated using an rpm of around 60-90 based on common pedaling cadence, and cross that with the nominal wattage rating...

using this page http://www.wentec.com/unipower/calculators/power_torque.asp and inputting .75kW at 80rpm i got 792 lb*in of torque, which would be 66 ft*lbs. Am i doing that right?

I'm trying to estimate how much torque i'll be putting to the rear hub, to make sure it wouldn't be overtaxing a nuvinci hub (and because i like geeking on spreadsheets).
 
TroySmith80 said:
Does anyone know how much torque these things apply to the cranks at full power? How would one go about calculating that? I suppose it could be very roughly approximated using an rpm of around 60-90 based on common pedaling cadence, and cross that with the nominal wattage rating...

using this page http://www.wentec.com/unipower/calculators/power_torque.asp and inputting .75kW at 80rpm i got 792 lb*in of torque, which would be 66 ft*lbs. Am i doing that right?

I'm trying to estimate how much torque i'll be putting to the rear hub, to make sure it wouldn't be overtaxing a nuvinci hub (and because i like geeking on spreadsheets).
Click to expand...

That's pretty close. The drive is rated at 80nm. I think the nuvinci will be pushed but will be fine if you treat it with mechanical sympathy.
 
Kepler said:
That's pretty close. The drive is rated at 80nm. I think the nuvinci will be pushed but will be fine if you treat it with mechanical sympathy.
Click to expand...

Thanks. Is that for the 750W? Where did you find the rating? Do they list torque for the other wattage ratings as well?
 
High starting torque, Max torque≥80N, good performance on climbing
Click to expand...
http://www.aliexpress.com/item/36v-500w-8fun-bafang-bafun-motor-Center-mid-drive-Crank-Motor-eletric-bicycles-conversion-kits/1390447604.html
 
TroySmith80 said:
Kepler said:
That's pretty close. The drive is rated at 80nm. I think the nuvinci will be pushed but will be fine if you treat it with mechanical sympathy.
Click to expand...

Thanks. Is that for the 750W? Where did you find the rating? Do they list torque for the other wattage ratings as well?
Click to expand...

Knowing what power the drives actually draw and what speed it it turns the cranks, just used the following formula Torque (N.m) = 9.5488 x Power (kW) / Speed (RPM). Seems to correlate with the advertised rated max torque.
 
dirkdiggler said:
Turned a corner and my rear derailleur burst apart. I don't know what happened or how. .
Click to expand...

Could be similar to my issue... a roller in the chain link got crush(deformed) resulting in link jamming and derailier noise... cheap chains or changing gear techniq need to improve.
 
I am waiting to see if my derailleurs last with the BBS02 - very impressed with the 750W motor. If they don't, I plan on using a NuVinci N171.
 
I emailed Nuvinci to ask about running e-power through the hub. Here is their response:

Troy,

The N360 is only approved for 250W mid mount motors at this time. We are certainly looking develop the hub along with the growth of electric motors and increase of power. We recommend a 2.1:1 minimum sprocket ratio when running a system with a mid mount motor.

Good luck.

Jeremy Leffingwell
Bicycle Engineering & Product Support Technician
Fallbrook Technologies Inc.
Click to expand...

and for reference, here is the email i wrote them, that he was responding to.

Troy Wrote:
Hello,
I'm interested in using a nuvinci hub in an electric-assist bicycle. I would like to use a crank-drive motor like the Bafang BS01 or BS02. This motor uses a double-reduction to drive the cranks, adding it's power to my own, all of which is then sent through the chain to the rear wheel. I'm sure you're very familiar with all of that (or at least with systems like the panasonic or Bosch crank drives, which are similar).

My question is how well will the hub cope with electric-assist systems like the Bosch or Bafang? Some are very low power, around 250 watts. What about higher power like the 350 or 750 watt Bafang systems?

Your website says all over that Nuvinci is great for ebikes, but doesn't really state whether that means a front-wheel powered hub (obviously no problem for the nuvinci) or a crank drive (mid drive) system. Some of the max torque input specs i've seen for the hub suggest that this could be a problem. I've heard that efficiency of these hubs drops dramatically at high power levels, is that true?

I love your product! If it is not quite up to the task of these kinds of power inputs, perhaps you could consider making a heavier duty version to be used with these e-assist systems?

Thanks,
Troy Smith
Click to expand...
 
Thats interesting. Utah Trikes is advertising that they work well with the 1000watt ecospeed drive. I wonder if they have had any warranty claims on the N360?
 
teslanv said:
I would ask Fallbrook about their N171b drive.
Click to expand...

[pre]Torque, Power, and Speed Limits*

Maximum Sustained (Pulse-free) Input Torque 65 Nm (48 lb-ft)
Maximum Instantaneous (Spike) Input Torque 130 Nm (96 lb-ft)
Maximum Sustained Input Power 5 kW (7 hp)**
Maximum Recommended CVP Speed Input: 1000 RPM / Output: 1000 RPM[/pre]
http://www.nuvinci.com/09_lev_kit.asp
 
Yes, in a follow up email he stated, "the N171 was developed for bikes and light electric scooters. You will probably be interested in the Developer’s Kit. http://www.nuvinci.com/09_lev_kit.asp "
 
m4s73r said:
Thats interesting. Utah Trikes is advertising that they work well with the 1000watt ecospeed drive. I wonder if they have had any warranty claims on the N360?
Click to expand...

Are they using the 360 or 171? Or both?
 
Time to admit I have too many projects on the go. So my Greenbikekit throttle+PAS 350W unit is in the for sale thread if anyone's interested,
http://endless-sphere.com/forums/viewtopic.php?f=31&t=57577
Open to offers. It's also on ebay.com.au with two days left - can't take offers if it sells there.

Cheers.
 
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