electric bike

Hi Andrew,

This is a very interesting project. Why don't you break it down and ask some specific questions that you have and see if any of us have answers for you. Your text above doesn't really pose a concrete question and I know from experience that the guys will help but they won't design it for you. I look forward to following your progress.

John

Thank you , i will try that

well the first question that i have that is probably a good starting point is what voltage should i use , I know that i am going to have to arrange some lithium cells to make a 32v or 48v and so on battery but i don't really know what the ideal voltage would be as from there i could start looking at motors and how meany cells in what arrangement i would need , thank you.

Hi Andrew,

For some initial battery information, check out batteryuniversity website, it has some useful information. You'll need to intimately get familiar with how cells behave, because there could be consequences to arranging them in a battery, and charging/discharging them. So basically a lot of theory/reading up, but it is important.

Also, another suggestion is that it might be better to make a scaled down, or slightly lower-power model first, to get used to the challenges that you will experience when you scale up. A lot of the radio controlled car hobbyists have been down the path of motor and battery selection, so you'll learn a lot just from observing what they did, and their design decisions*. You'll start noticing things like battery safety, choice of wires, motor performance, etc. The RC hobbyists have some very high performance models that might approach the level of performance you might be looking for anyway. Since RC model hobby has been around for many years, you'll also find good books I think, and for practical information even magazines dedicated to it, or perhaps back-issues at your uni library.

* My first (joint - I'm not taking all the blame : ) RC project as a teen caught fire over a weekend! So even at this smaller scale one can learn a lot...

thank you for this advice I will look into RC and scaled down idea first!

And remember that it "may look complicated, but if you think about it, it is just a giant cordless drill with wheels!"

KillaJoule – Eva Hakansson

Hi Dave,

Great link! Loved it, I'd not seen this before!

I would investigate what voltages are being used for mobile wheel chairs and for the other commercial people movers like the hover boards. If you can find a voltage that is in commercial use you will likely find motors and other accessories available.

John

Hi

So after doing some research I have decided on a 48V-36V set up i think 48V will be better just for power , I have also learnt a few other things about motors Firstly that voltage somewhat correlated to velocity and current and torque are related but more current doesn't equal more torque due to back EMF's and stuff, secondly i have learnt that a brushless motor that is an out run motor would be ideal for this project mainly as low speed high torques are way more effiencient that low tourqe high speed. brushless just because they last longer and are generally considered better choices my next step is to find just the right motor and also a controller for the motor I am becoming more and more keen to make my own one but i dont know how complicated that is for a brushless motor (brush being super easy) my next question would be to buy or not to buy a controller ?

p.s is this a good place to document any kind or research i find ?

pss could people correct me if my research is wrong