Which controller to choose? Ebike, 27 km/h, programmable

[Kittenrainbow]

hey guys

I finally want to do it and convert my existing bicycle to an e-bike.
The goal is to commute to my workplace (6 Km one way, downhill on the way there, uphill on the way back).

In my country it is legal for an ebike to drive about 25 km/h with pedalling and 20 km/h without pedalling.
As a motor i want to use a bafang cst. It has about 250W at 36V, so it draws about 7A. I want to use this motor because it enables me to use my existing gearing.

I am looking for a controller which can drive this motor and which gives me a possibility to programm it.
The reason is that I also want to have to possibility to drive 30Km/h / 25 km/h (so it would be a bit too fast, but I think it is in a certain margin so it would not be perceived).

Which controller can you recommend? I looked for a big comparision chart of controllers but couldn't find one, and all threads and questions i could find on the internet have different requirements.

I hope you can help me=)

Regards

 

[melodious]

When describing an electric build around a motored wheel hub, it's best to give your bicycles wheel size. It will get you better responses on what should work. A 20" BMX style wheel produces noticeably more starting torque (aka thrust) than the larger 24, 26, 27.5, 29 wheels. My dinky 20" folding bike had a geared front 36v hub @12a controller and it remarkably got me up some steep roaded inclines, never getting overworked (no excessive heat produced). But, let's assume you have a 26er and go from there

Your thinking is flawed. Focus on the volts. That's what will determine your top speed. 36v in a 26" wheel is typically 18-20mph whether you increase the controller amps or not. But increase the volts to 48v (a very popular voltage) and your top speed will increase to roundabout 25mph (a 5mph increase in top speed). 25mph is a good & safe bicycling speed for on road traffic and is the E.S. conservative standard, anything faster is going to drain more battery reducing your range. But who says you have to ride at 25-30mph+ speeds all the time? Many are using the max speeds only for keeping up with traffic or for making a passing maneuver. They are happy riding in the sweet 20-25mph zone, for most of the ride.

Use this simulator tool to help you on your controller choice. I didn't specify a particular controller for you. Part of the fun of building is the learning process that goes with it. :wink: I'd rather make a mistake with a controller choice than a battery choice though. Controllers are ohso much cheaper.

IMO, a 48v battery is your starting point. Use a controller that can supply a 3 speed switch. 1 & 2 speeds are your normal settings (i.e. 15-20mph) and 3 is your performance setting (25+mph).

Merry Xmas! It's that time of year where I get long winded... :lol:

 

[wesnewell]

All ebike laws are just stupid. A fit rider can go 50 kph without a motor for quite a distance. It's not even worth adding a motor if you limit it to 25kph Everyone without motors will be passing you. I'm almost 70 years old, way out of shape at 5'6" 270lbs and even I would be passing you at 25kph. Well maybe not for long, but you get the point. Think how much hell would be raised if they tried to limit the max speed of automobiles. Dumb, dumb, and dumber.

 

[opperpanter]

All ebike laws are just stupid. A fit rider can go 50 kph without a motor for quite a distance. It's not even worth adding a motor if you limit it to 25kph Everyone without motors will be passing you. I'm almost 70 years old, way out of shape at 5'6" 270lbs and even I would be passing you at 25kph. Well maybe not for long, but you get the point. Think how much hell would be raised if they tried to limit the max speed of automobiles. Dumb, dumb, and dumber.

I agree the laws are stupid, but 25kph is not a speed at which you'll get passed a lot.
At least not in The Netherlands (bicycle capital of the world) on regular street traffic. Mist people ride about 20kph on unassisted bikes here.

 

[MitchJi]

Hi,

http://endless-sphere.com/forums/viewtopic.php?f=31&t=65031#p976242

 

[Kittenrainbow]

Hey Guys

Sorry I left out the wheel size, it's 26".
I think 25 to 30 km/h is a fine speed for me, I drive normally at 15 to 20 km/h.

Aren't there any controllers which are just "stupid ESC", like in the RC edge of electronics? I ask for it because I do alot with electronics for hobby and it would be easy for me to build a small unit which controlls the ESC (via PWM) and have a LCD. I could then implement the different settings by myself, exactly the way how I want them
Unfortunately I am not very experienced with high voltage and high amperage builds, and therefore it would be nice to "export" those difficulties in a of-the-shelf ESC.

Regards
me

 

[d8veh]

A couple of things: Firstly, the current you mentioned of 7A is too low. There's two common versions of that motor. The 250w/350w one, which runs up to 22A and the 500w one up to 30A. The 250w is a rating, not an actual power. Secondly, most controllers that have LCDs have adjustable maximum speed, so you have a lot of choice of controllers. Normally, the guys that sell the motors also sell controllers. You want one somewhere between 18A and 22A, assuming that you have the lower powered motor.

Those downtube batteries with included 20A sine-wave controllers that BMSBattery sell would be perfect. They have the LCD, so you can program the speed to whatever you want, although the motor will probably max out at about 30 km/h (without speed limit).

 

[Kittenrainbow]

Hi and thank you for your answer

But I really start to like the idea of constructing a controller on my own. I could add a bluetooth module to beam statistics to my smartphone, I could implement other features directly into the controller and so on.

Does anyone of you know a "dumb" ESC for such a Motor for 25A / 48V? Controllable by PWM, suitable for a motor with hall sensors