ultra quick bike conversion

[skewbe]

I don't know if it will go fast/far enough to matter, maybe going through the gears would help, but here is a quick and dirty conversion idea that may or may not work if you have a bike laying around and a spare $50 for a trolling battery:

[GeekGuyAndy]

Are you going to be trying that?

[skewbe]

I wish. Seriously, the wife would kill me if a bike showed up. I just wanted to put it out there.

[GeekGuyAndy]

"Oh what's that dear? There's a bike on the front step? Who put that there?" Think she'd fall for it? Being a moped driver I always wondered why I hadn't seen any electric mopeds around. I bet that would be an easier/smaller conversion

[Ryland]

main problem that I see is that the starter motor is designed to run for up to 10 seconds at a time, when I've worked on bikes, and ran the starter for more then 10 seconds I noticed that it got really hot, about 30 seconds and it gets hot enough to burn your self on, the bearings and brushes are also designed for short bursts, and not continued running, a starter might see up to an hour of total use befor being rebuilt if you add up every 2 second burst that it's used.
it's also geared low enough that if you are lucky, in 5th gear you might get up to 15mph

[skewbe]

Ok, safe to say that this goes in the "you'd have to be bored" category

[Bill in Houston]

Maybe something the size of a car starter would work. If you put a one-way freewheeling clutch on it, then you could run the starter for a few seconds, and then coast, and then run it, and then coast.... The starter could go down where the motorcycle crank is/was.

[sandalscout]

Originally Posted by GeekGuyAndy

Being a moped driver I always wondered why I hadn't seen any electric mopeds around. I bet that would be an easier/smaller conversion

I actually have a Tomos Bullet Moped with a bad engine in it. I plan on converting it to Electric in the coming months. I have several options, just not sure how much money I want to drop into it. The cheapest involves using a modified car starter.

[GeekGuyAndy]

How about just taking out the engine, put in a 12v DC motor and belt that to a wheel?

[sandalscout]

That's the plan in the most basic form, but I've got to source a controller, batteries, charger, etc... I plan on mounting the motor roughly where the engine was, and running it off of the original chain drive. I've not sat down and TRUELY figured it out, so I'm not sure what voltage/amperage ratings I need, etc....

[Bill in Houston]

I have sort of wondered if you could avoid the controller, and just have an on/off. In a high enough gear, the starting shock would not be too much...

[MetroMPG]

But the current draw would be big.

One of the good things about a controller aside from the smooth, smooth goodness, is it protects the motor, wiring & battery from excessively big amps.

Of course if you instrumented the thing with an ammeter and did a little bit of testing to learn what gear/speed/grade combos work without heating up the components too much, AND you keep an eye on the meter, a simple switch would be OK.

[Bill in Houston]

Ah, yeah, I tend to forget that electric motors will happily, peacefully destroy themselves if you ask too much of them.

[MetroMPG]

Then again, you could also just put a properly sized fuse or circuit breaker in there with the switch. That'd protect the motor without a controller. (Should be a fuse in there anyway so if the controller fails, you still have motor/circuit protection).