Electric motor gearbox with pedals.

Discussion in 'Electric Bicycles' started by Garp, Aug 30, 2010.

  1. Garp

    Garp Member

    I'm keen to mount an electric motor on the gearbox I made for my mountain bike. I think that being able to use the power through gears will be an improvement.
    I intend using Makita 36v batteries. I want to be able to plug in various combinations of up to 4 batteries. I want software to be able to detect this and run accordingly, and the whole thing must be less than 50 pounds in weight [ much less with only one battery]. It must be waterproof and be able to take a pounding.
    I need to research controllers and battery management software, also there are some interesting motor designs used in the Solar Challenge races that would work well with my setup.
    It good fun with a petrol engine but I want stealth sometimes, and instant torque.
    Electric is the way to go I reckon. I realized that halfway through building this one.
    I wouldn't have gone to so much trouble if I'd started out electric, but it may still have some relevence as it is pretty neat.

    Attached Files:

  2. Ypedal

    Ypedal Member

    The cells inside makita packs are good, sony 18650 LiMn 1.5 ah each so you need 10 in series for 36v and X amount in parallel for a usable capacity depending on how far you want to go.

    BMS ( battery management systems ) are available, again, depending on your needs various options out there.. signlab is popular for low to moderate power levels.. www.tppacks.com have boards available and are always working on new versions.. if you are not very experienced in battery tech you might want to consider a ready built pack .. www.pingbattery.com .. or even e-bikekit.com for a nicer pack in a metal box with built in BMS if you stay at the 500w kit level..

    using a motor thru the gears, a good idea if you have serious hills to climb and want to do it with limited power.. but a hub motor makes life alot easier and is much more stealth if that matters to you.

    RC motors are small and powerfull but rev up high and need alot of reduction to make them work properly, what ratio is your gearbox ?
  3. Garp

    Garp Member

    Thank you for your great advice, I'll study those links.
    I wanted to use the Makita 36v pack because I already have some, they are tough, and a quick web search seemed to indicate that they have already been used on bikes.
    Most of my riding is offroad so I'll need all the hillclimbing ability I can get.
    The reduction is 100/1 on this box but I could easily change that either way.
  4. Garp

    Garp Member


    This is the battery arrangement I will use.
    This project may come together soon as I am moving to coast and I'll need an ebike as a runaround. I've been looking at ready made bikes but I haven't seen one that impresses me much, apart from the Optibike which is way too expensive.
    I think mine will be better than anything I could buy but I don't have time to mess around with it at this point. What a dilemma!