Electric bicycle build

By bcubed · Apr 10, 2010 · ·
  1. bcubed
    I'm set to add an electric motor to my old Trek road bike, because...well, because I can, I suppose. I thought I'd start a blog thread about the build and the results. Also, to see if any other nutjobs out there have experience they'd care to share.

    What I've got:
    1. Bicycle
    2. DC motor (1300W, 90V, 3000RPM) from a garbage-picked treadmill (motor works; electronic treadmill controls don't).
    3. 12V Pb/H2SO4 battery
    4. 12VDC-to-115VAC inverter.

    What I plan to do:

    Step 1: feasibility test--attach a ratcheting sprocket (from a dead child's bicycle) to the drive shaft of motor. Link motor to front chainring of bicycle. Then...as a "proof of concept" test, run the battery, through the inverter (and a bridge rectifier that I'll bet is somewhere on the treadmill carcass) and to the motor...and the wheels.

    Once I can demonstrate this actually produces motive force, I can worry about trivialities (such as a throttle). Also worry about acquiring a power pack a bit more efficient than what I've described.

    I'll continue to update this thread as this lunacy progresses...

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  1. Jasim
    Very cool. Thanks for sharing. I sometimes wish I was more mechanically inclined.
  2. xenos
    hahaha swim has had this idea and thinks he has the correct ingredients. however that "think" is very important when dealing with motors and wattages.. he has a motor from a weed-wacker and from a vacuum, but still needs to look at their properties(though they are in good shape). he also has many 12v Lead-case rechargeable batteries, so obviously more research remains for swim. your blog will help though thanks!
  3. MrG
    Interesting, although one quick question, does it have to be a dead child? Couldn't you just wound the kid and then take his bike? It all seems so violent, this green living.
  4. Potter
    IS there anything that can't be done with an old treadmill? I'm looking at wind turbines from one of those right now.

    Awesome project!
  5. bcubed
    Touche', smartass:laugh:

    I meant the *bike* was dead, not the child (at least, not that I know...and I'm pretty sure I have "plausible deniability" about the whole sordid affair).

    Welding awaits...as for now, I'm making do with the unpowered version--damn 15c/mi in gas for the work truk just ain't happening.
  6. MrG
    LOL, anyhoo, one suggestion that might be worth considering that is on-topic is whether one could incorporate a Zinc-Air fuel cell. On the basis that there is a mechanical process going on with the riding of the bike itself, the removal and replenishment of zinc could probably be factored in to the on-the-go mechanism.
  7. Potter
    Bcubed, it really does sound like it's a bike from a dead child, not a non-functioning children's bike.

    A panda walks into a café. He orders a sandwich, eats it, then draws a gun and proceeds to fire it at the other patrons.

    'Why?' asks the confused, surviving waiter amidst the carnage, as the panda makes towards the exit. The panda produces a badly punctuated wildlife manual and tosses it over his shoulder.

    'Well, I'm a panda,' he says, at the door. 'Look it up.'

    The waiter turns to the relevant entry in the manual and, sure enough, finds an explanation. 'Panda. Large black-and-white bear-like mammal, native to China. Eats, shoots, and leaves.'
  8. Pringles
    This is an interesting idea, I'm wondering how much more efficient it would be if you could do without the inverter / rectifier & build a battery & charger.

    I made a nice bright lamp for my bicycle using 48 ultra bright white leds. I took them from an led lamp that cost £4 from asda. Also i made a 12v battery using 4Ah nimh cells bought from Aldi at about £2 for 2 i think. So i dont need to charge them up very often. My charger is a home made power supply with current limiting & when the battery starts getting warm i know they are done. When they melt & i throw them in the sink its because i charged them hard & forgot about them :s
  9. bcubed
    Wow, getting a lot of responses...good thing, motivates me to keep going!

    Couple of replys:

    First, Potter: yes, upon re-reading it does indeed sound like I'm talking about a dead child vs. a dead bike. That's why I was merely pretending to me pissed at Mr. G. Figure I'll just leave it be though, as I'm not submitting it to my English prof anytime soon.

    Second, Pringles: Yes, it'd be much more efficient to use (almost any other) source of power other than a 12V lead-acid battery, converted to household current and then rectfied.

    What I was doing was basically a "proof of concept": to see if everything actually works before I invest money in stuff like battery packs and the like. Once I verify this, then I'll worry about getting a nice, efficient setup.

    Since I already have the inverter, that's why I'm employing it in the proof-of-concept tests.

    However, in the larger sense, I'm using the e-bike to substitute for a truck that gets roughly 18 MPG. Given that even an "inefficient" motorized bicycle setup will be orders of magnitude more efficient (and, importantly, cheaper) than the truck, one could argue that running a wasteful setup is a better solution than waiting several months until one can afford a "proper" setup.

    Right now, I'm waiting on funds that won't be available until 4/21. I'll have much more to report (incl. hopefully some pics!) then.
  10. xenos
    Ah, let swiu not speak of why you will not be able to until 4/21 :D:smoker:
    In swim's similar project he is going to build buck converters to work with his lead 12v batteries, thes use a switch between a capacitor and a resistor creating a step-down or step-up DC(?)-DC converter.
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