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I have a lot of respect for the Chinese approach, it's not perfect but it's realistic and economical. They already are world number 1 in solar and wind energy although the Germans still produce the best technology in the world. Some of the green tech like ebikes and ecars can really be cottage...

I suspect a lot of us own more than one bike because they are small, light, cause relatively low impact on earth's resources and frankly, so cheap. Most e-cars do not fit any of these criteria but ebikes do. So a lighter version of the Gwiz would still be light, small but more affordable. The...

Imagine that a clever company rents out batteries for e-vehicles, then suddenly, refuelling won't be so difficult. Manufacturers will use this facility if it exists. At present, there are too many manufacturers, the market is still finding out winners and losers. They make very powerful e-cars...

No. Transition from fossil fuels to renewable energy is exciting, from petrol to diesel is plain boring. Diesel it has no notable advantages over other petroleum products, finds favour now, gone in 20 year time (may be little more but before 30 years). Personal transports will get smaller and...

Thank you very much to you both, flecc and NRG. The link provided by NRG is particularly useful, it has a very good picture of the rollers in the clutch mechanism. Here comes a daft question: has anyone tried to modify the central and planet gear assembly on this motor?

this link is now not found. Flecc, could you give me more information on the Bafang clutch? the szbaf.com website does not have much. http://www.szbaf.com/images/product/size/200911191349487503.jpg

Agreed but it's not their job to add management function to their motors. Otherwise, they would have added digital control such as I2C bus. NRG: thank you very much for your input. I sincerely don't know if it will work. Maybe modern controller have already got torque boost in low revs.

Yes, this is true. The battery voltage cannot change, at maximum output, the controller delivers pulses corresponding to around 36V at 10A. The DC to DC converter outputs much higher voltage at shorter pulse width. Assume that the SB has 10 poles, has constant impedance, admits 10A as nominal...

Yes, this is true but the controller outputs up to 36V at 10A supplying the DC/DC boost, at 100 RPM, the latter should be able to output 48V 5.2A with ease. Giving 90% overall efficiency, the controller would only need to use 77% of the max width. There is a driver after the DC/DC converter...

The idea is to make a programmable stepup DC to DC converter. Outside the 50-100 rpm range, the gain is set to 1 to protect the controller and the motor. Inside the range, the booster is active and the gain of this stage is inversely proportional to the RPM. The solution is simple and should...

I tried the emulator, it's useful but it can only calculate for a few existing controllers and can't factor in any add-on. Linear Technology has a single chip solution for a DC / DC converter. It's nearly 95% efficient so a credible alternative to a mechanical solution. My device (only on paper...

Frank, I try to design an addon for the Bafang kit that should help it deliver much more torque at low speed, I try to get about 22Nm at 100rpm, 40Nm at 50 rpm. Outside this range, the motor response won't be affected. Would you be interested by such a device?

jbond, I could not make head or tail out the the website data either. The guy climbed up to the top of the mountain, putting in a fair amount of leg power. Then he produced a near straight curve (yellow N). I think the effective limit of the SB at low revs is determined by the maximum torque...

NRG: I am sure your are right, that's why I was looking for power outputs at various RPM. I thought the main feature that the Panasonic drive has over front wheel SB drive is more power at low revs. Vfman pointed me into the right direction but with hindsight, the dataset I got from that web...

I don't know NRG. If you climb hills at 100 rpm on 700C tyres, your speed is 13kph. The SB motor offers only 154W of assistance. At 50 rpm, your speed is 6.5kph, the motor helps with 77Watts. It's useful but not good. If I can improve the power output in this band, there won't be so much appeal...

the future is orange.

Hello Frank, I saw on google a picture of a SB motor burnt at 60V, the nylon gears could not take the power and melted. 60V may be the upper limit in input voltage for the SB motor, but then, the motor was pushed so hard that the gears may have sufferred from heat rather than just from excessive...

The data from that link seems to suggest that the controller is not intelligent, P (Watts) = 1.54 * N (rpm) all the way down to zero. I feel so stupid but I have to ask, how do I add an image from my PC to this post? Can anyone also help me find a chart for POWER versus VOLTAGE for the same...

has anyone tried to get the Bafang SWXK-5 to cough up more Watts at low revs?

vhfman, thank you for that link. Yes, it does answer my question but just to be sure that I understand the chart, the yellow line is marked N (rotational speed RPM) only goes from 223 rpm to about 180rpm. How can I work out the power output at 100 rpm? is it straightforward lookup at the two Y...