Electric assist bicycles

[puddleglum]

Is your motor a hub motor or a chain driven brushed motor?

[Daox]

The motor I have is very similar to this one. It is made for an electric scooter.

Brush DC Motor for Electric Bikes, Scooters, Mopeds, Motorcycle - 24V 250W

[puddleglum]

I used a motor just like that for the scooter I built for my son this summer. Endless-sphere.com • View topic - Stand up to Mobility scooter conversion it works quite well but I think you will need to run it with a 24v pack it you want it to have enough power to do any good. Also, a controller for it will be 24 volt. Check out the online scooter parts sites. Parts are pretty cheap and since you are in the US shipping shouldn't be too bad. I didn't buy any thing from them because of the high shipping to Canada. If you could find a good deal on 4 more A123 cells, you should be able to stay within your budget. I have the scooter geared really low, but it has lots of torque. I think, even with higher gearing for a bike, it should be fine for a pedal assist if you don't need too much speed. The only problem might be figuring out a way to mount it. I think you will need a second freewheel or something.
Another cheap option might be to pick up an ebike kit off ebay, but I have no idea which sellers are reputable.

[govman6159]

Hey Daox,
I built this ebike for about $600 (see attachment). IMO it has a lot of advantages over a hub motor ebike like
1) You can shift gears to get the best use of the motors power
2) You can pedal if you want but you don't have to
3) Top speed of 25 mph
4) 20-25 miles of all electric range

If your interested in more details let me know. You could do this with your motor but, you will need more cells. 175W will be nothing and even 350W is severely underpowered. I'm running 500W and I still want more. I would really like a 36V/1000@ motor but its just not in the cards for now. I'm using lithium (LiFePO4) batteries as well. My pack is 24V/30ah and it is sufficient for my 17 mile round trip commute.

[Daox]

Looks pretty nice Govman6159. That is pretty much what I was thinking of doing. More info would be great.

Puddleglum, that is pretty cool too! I love how it folds up. Very nice work.

[govman6159]

I would be happy to be of any assistance to you on your build and happy to provide you with whatever info you need. What specific questions do you have for me?

Here is a pic of how I mounted the motor.

[sendler]

Originally Posted by govman6159

I would be happy to be of any assistance to you on your build and happy to provide you with whatever info you need. What specific questions do you have for me?

Here is a pic of how I mounted the motor.

Where do you get the gears?

[govman6159]

I got some from sickbikeparts.com and others from electricscooterparts.com. The gear you see is a 96 tooth #25 sprocket from electricscooterparts.com. Its off of a Schwinn S500 scooter. I ordered the front freewheel bearing from sick bike parts. Both sites have a myriad of parts you can use for converting your bike.

[puddleglum]

govman, nice job. It looks like your motor is driving the crank through a freewheel, right? How do you keep your motor from overspeeding your crank at full throttle? Unless you have a really low speed motor, the gearing doesn't seem low enough. Am I missing something?

[Daox]

Originally Posted by govman6159

I would be happy to be of any assistance to you on your build and happy to provide you with whatever info you need. What specific questions do you have for me?

Do you have any form of BMS for your batteries?

I checked prices on the controllers on the electric scooters site. They're way cheaper than other ones I've seen. Is the quality any good? $30 for a controller makes me wonder.