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WannabeEVer 11-29-2008 02:26 AM

Starter motor E-Bike
I've had this idea for a while but only recently found a place where someone else had done it online. I was thinking of mounting a starter motor from a car onto a bicycle and power it with ATV batteries. I've got my bike, motor and I've started to build the lifting lever to take the motor off the tire. Yes, the motor will actually be rolling on the tire, i did this to minimize any gearing i'd have to do by attaching it to the sprocket. I'll use a knurled cylinder to replace the sprocket on the starter to keep grip on the tire. The rider will still be able to pedal and if they have the motor down on the tire and they can recharge the battery by pedaling with the regen braking. Instead of a controller I'm going to use a switch and 2 12v batteries. The switch box will have an on/off and a 12v/24v switch in it so the rider will first have to get the bike up to speed then they can engage the motor and keep a current speed. I'm hoping to have it done before the end of January but I'm doing it as a school project. The cost so far: $0 :). I'll try to get pics up soon.

bennelson 11-29-2008 10:05 AM

I've seen people do that before. It's cheap and works fine.

Don't expect huge range and speed, but its a fun little project. Go for it!

order99 11-30-2008 08:22 PM

I'm planning something similar-I just discovered a nice cheap Touring bike (single gear) and i'm going to take advantage of its mechanical simplicity by attaching a sprocket beside the wheel opposite the chain and running a second chain to the motor behind my seat. My choice of motor is a 12V, 50A Ghia generator-several local mechanics tell me the motor will withstand up to 2400+ RPM for an extended period, and at 24V it's going to max at 1200-so i'll also be foregoing expensive controllers for a controller/throttle box(a model railroad transformer rated at 24V and 120A, and i'll add a spring to the sliding lever for a deadman switch).

The bad news is i'm broke, so i'll be waiting a few weeks before I can grab some Lead Acid batteries rated at 12V 25Ahr-but at least I can use my 12V 13.5A charger so I won't have to buy one (and Balancing won't be a problem since I can only charge one at a time, mixed blessing there). Oh, you and I will both need a simple Voltmeter so we can read our 'tanks'.

The OTHER bad news is that I live in the Boonies, so my EV will be a toy at best, the nearest town is 11 miles away. :( Still, I have everything but the Gears and Batteries just lying around, may as well put my theory to the test!

BTW, have you considered building a superlight Bike trailer and adding some extra packs in parallel for extra range? The Instructables website-

Instructables - Make, How To, and DIY

-has dozens of DIY Bike trailers, most of them created from somebody's latest dumpster diving session...i've made the PVC one already. Eventually, you and I might get the speed and range required to either get pulled over by the Cops or get run over by traffic... :o

Just to to be clear though-you finish your Project, you're gonna have to call yourself something else... :D

WannabeEVer 11-30-2008 08:42 PM

From what I've seen of starter motor bikes, range shouldn't be too much of a problem. The main source of information I'm using to build mine is " y=0" and they guy there used two 18 Ahr batteries and said he got over 20km's out of them on very hilly terrain. The little bike computer is an awesome idea, it's got an odometer, trip distance, trip average speed, current speed and trip time. I'm definitely getting me one of those. I also love the little switch box idea instead of spending too much money on a fancy controller. Also, I'd like to thank Amigo's Autowrecking in Clavet for my free starter motor.

order99 11-30-2008 11:20 PM

Er...I don't recall mentioning a Bike Computer-did you find one at Instructables? I'm just going to fasten a small box to the handlebars, bolt the HO switch to the underside and a Voltmeter to the top. The local Wal-mart does sell a self-contained gauge though-Speed, mileage and clock, uses a watch battery. I doubt i'll go fast enough to need one, but at $5 I might pick it up anyway.

Nice to know you can get 20 KM on hills with a Starter motor and 18Ahr, but i'd need over twice that for even a Grocery run-of course i'll still have my pedals (huff, puff, puff...). This is where the PVC Pipe Trailer would come in though-4 extra Batts wired in parallel to the main circuit would triple the range while remaining at 24V, for 60+Km(38 miles) and still have space for about 3 ft of cargo. The bad news of course is a) I can't afford ANY batteries right now and b)i'd have to charge six batteries in a row with ONE charger! :( Of course by the time I have money for 6 Batts I might have enough for a Marine Multi-charger w/ separate ports for each cell...after I get my next Temp job of course-

(razzzefrazzen Recession...)

Still, I can bolt on the mountings I need and use the Bike as is until I get my next check-after that i'll have at least the two Batts for Power Assist and use my legs for the most part(wheeze, gasp...).

Glad to know you like the HO switch idea. The box acts as both a Potentiometer and a Voltage limiter, and if you reside near any Model Railroad stores you could probably find the odd one available (the 12V are far more common though). I'm only using one because my Dad used to collect Train sets-I cleaned out the barn last month and found all my EV parts just sitting there! I checked the corners for some NiMHs or NiCads but I guess that would be pushing it... :D

WannabeEVer 11-30-2008 11:25 PM

The computer i was talking about was with that website that i had there. What about regen braking though, that would save you a lot of power too. If you run out of juice you could pedal with the motor on, yeah it'd be a little tougher but you'd be putting power back into the batteries.

order99 12-01-2008 01:53 AM

Ah, found it!

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Ryland 12-02-2008 10:52 AM

starter motors are designed to only run for a few hours total in their life and only for up to 10 seconds at a time or they tend to overheat, look at the size of them, they are around 2 horse power and the size of a quart jar, the 2 horse power continues use motor that is in my garage is about the size of a water melon.
starter motors also tend to have very small soft copper brushes, instead of the larger carbon brushes, they can handle more current but they tend to wear really fast, but if the motor only needs to last a few hours then that's ok.

order99 12-02-2008 10:21 PM

You know, the more I look at the Autospeed article, the more I wonder-do those double-switches use a Resistor to go from 12V to 24V, or is it simply two separate circuits with two separate switches? It seems like such a simple idea that I have trouble wrapping my head around it-the fact the author of that article could get Regen so easily that is. Guess my lack of Electronics training is i'm tempted to cross 'expensive Controller ' off the blueprints for my Dream EV and replace with 'Resistor/Contactor Array'! I'll be sure to use a different color crayon... :p

Ryland-i've no idea what year model starter WannabeEVer has, but would starter motors from older, obsolete models have the durability required for an EV bike? I've seen full-sized cars converted with old Aircraft starters, after all. If not, i'll point him to a few cheap Generators I found on Ebay($7-20 if you want to clean/recondition, $70-100 for perfect).

captainslug 12-02-2008 10:46 PM


Originally Posted by WannabeEVer (Post 75654)
The computer i was talking about was with that website that i had there. What about regen braking though, that would save you a lot of power too. If you run out of juice you could pedal with the motor on, yeah it'd be a little tougher but you'd be putting power back into the batteries.

Regen will only marginally extend your range (about 10%). And pedaling with the regen on will be almost as hard as trying to pedal while holding the brake down all the way.
For a low-power vehicle such as an eBike, regen offers very very little.

If you want to build an e-Bike I would recommend looking into hub motors. Golden motor offers some very nice kits in a variety of price points and performance levels.
Hub Motor, Regenerative Braking Controller, LiFePO4 Battery Pack, brushless dc motor, electric bike,power wheelchair,bike conversion kit

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