Bafang Mid-drive

[z0mb13e]

I applaude anyone who takes the time to put something like that together...

Now back to my prgramable controller interface - my only outstanding project.

But the controller really peaked my interest. Are you building a motor controller from scratch or adding to an existing programmable controller?

I've been playing with the arduino and was thinking it would make a good base for a DIY open source controller...

 

[Deleted member 4366]

I'm making an microprocessor-based interface between the throttle/pedal sensor and the controller to give a more sensible and programmable power profile. I may even add a speed sensor.

I see a problem with existing controllers that want to give more power when you pedal harder or faster. To me, that's daft. It should be the other way round, so that you can choose how hard you want to pedal and choose how much power you get, with more power as you pedal less - if you want. You can more or less do this if you have a throttle, but it's almost impossible to hold the throttle constantly in the right position. On two of my bikes I use a potentiometer as a throttle and this is much better as it feeds in more power automatically as I slow down because it works as a speed controller - trying to maintain the speed. I want to trigger the potentiometer throttle only when I pedal for a more natural effect.
So far, I've managed to get an output in the right range (1 to 4v) that comes only when I pedal, which I can set with the pot. I want it to be overridden by the throttle.

The software that comes with this microprocessor is very simple to use but limited in what it can do, so I'm having to be creative when programming.
Does anybody know how much current the pedal sensor 5v line can supply because I want to use it to power my microprocessor?

 

[NRG]

On the Xiecheng 116 based controllers I've messed about with the 5v line is supplied from the same linear regulator that powers the rest of the logic circuit IE: its not driven by the microcontroller so depending on the regulator you could pull 100mA or more from it. I've used the same supply to power the Jeremy Harris fuel gauge PICAXE based cct and LCD without issues so unless your current demand is high I do not think there would be a problem.

 

[Deleted member 4366]

Thanks for that: It'll make installation a lot easier.

 

[z0mb13e]

I see a problem with existing controllers that want to give more power when you pedal harder or faster. To me, that's daft. It should be the other way round, so that you can choose how hard you want to pedal and choose how much power you get, with more power as you pedal less - if you want. You can more or less do this if you have a throttle, but it's almost impossible to hold the throttle constantly in the right position. On two of my bikes I use a potentiometer as a throttle and this is much better as it feeds in more power automatically as I slow down because it works as a speed controller - trying to maintain the speed. I want to trigger the potentiometer throttle only when I pedal for a more natural effect.
So far, I've managed to get an output in the right range (1 to 4v) that comes only when I pedal, which I can set with the pot. I want it to be overridden by the throttle.

I've been thinking the same thing, but I would also like a cruse control of sorts where I can set the required top speed for motor assist. Not to mention built in data logging.

As a matter of course I have always backed off the power when going up a hill so as not to over tax the battery and would be interested to see if it is possible to set a lower power mode for hill climbing that matches the speed I pedal at.

 

[umazooma]

....just tested the bafang mid motor at eurobike12 - into production in 2013 - i like. Torquey,smooth and quiet. As we joked at the exhibition, "Bafang is the Bosch of China." For the bucks, i doubt anyone will be able to beat this motor - will come with both/either torque sensor and speed sensor inside - separate controller - if the number of ebike producers that saw at eurobike relates to the number of buyers, then we are in for an explosion, but i fear it is a production/development bubble in the short term. May the cart follow the horse.

 

[flecc]

Thanks for the info umazooma. I fear you are right and that the choice now far exceeds the market capacity. Something will have to give and I forecast a number of names disappearing over the next two years or so.