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Old 01-08-2011, 07:56 PM
gokartmozart gokartmozart is offline
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Default Car Starter Motor

Can you use a car starter motor to power a small cart?

I have a starter motor, for a chevy larger V6 (3800). Anyone know what kind of torque these generate or what kind of gearing you would need?

I am going to build a small bar stool, and a simple starter motor and 12 volt battery could make it fun. I dont expect it to see much use so I am not worried about longevity, since the 12 volt batterty would need charged after a short time.
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Old 01-09-2011, 06:17 AM
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Nope wont work, its designed to be used for no less than 30sec-1min to turn over an engine and drains serious battery power, plus the weight of the motor will be against you.
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Old 01-09-2011, 08:17 AM
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I've heard that it can be done. It is heavy, it does draw a lot of current, it is prone to overheating.

That said, they make a lot of torque and should have no problem propelling you. Depending on the starter style, you'll have to modify it's output. Maybe you could mount a fan, and/or heatsinks on it to keep it cool. I have no idea what kind of RPM they tend to make. They heat may be less of a problem on a light kart, barstool or minibike, especially if it's geared decently. On an engine, the starter has to fight the engine's compression. A well-geared kart may be a lesser load.
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Old 01-09-2011, 09:04 AM
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Lots of Barstool racers are powered by starters, although the fact they're usually quite a bit lighter than karts helps the starters last longer. They found the gear reduction type starters hold up the longest because they use ball bearings to support the Armature. Conventional type starters just use Bushings that would wear out much faster.

Does your starter look more like like the top or bottom pic?



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Old 01-09-2011, 09:40 AM
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http://www.diygokarts.com/engine/car...onversion.html

http://www.diygokarts.com/images/sta...dification.pdf
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Old 01-09-2011, 10:11 AM
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Off hand, I think they run a 1:10-15 ratio to the flywheel, with a normal petrol engine (over here thats a straight 4, 1.5ltr) needing about 100rpm to start. Also the older style motors dont use a solenoid and use the inertia created to return the pinion after the engine has started, so it depends on how new your starter is as I have only a vague idea of what a a chevy larger V6 (3800) is.

There designed to give out most torque for the first turn of the engine, so it will have more torque starting out then as it continues to run.

My first reply kind of shot you down, sorry, but I just dont think it would be very efficient.
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Old 01-09-2011, 06:53 PM
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[QUOTE=KieranM;123866]There designed to give out most torque for the first turn of the engine, so it will have more torque starting out then as it continues to run.
QUOTE]

I was once told that as a rule, electric motors make their maximum torque at 0 RPM (ie starting), so therefore, yes. That's okay though, that's when you need it!
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Old 01-09-2011, 07:25 PM
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I don't know any details, but I'll second the opinion about barstool racers. I saw a short segment on a TV show about 20 years ago where they showed a barstool race. At that time they looked more like real barstools, and they held races on the city streets from one bar to another. Anyway, they were powered by car starters.
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Old 01-09-2011, 07:49 PM
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Best of using a cordless drill i think, check these out



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Old 01-09-2011, 08:47 PM
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Mine is not a gear reduction motor...simple starter motor. For my yard I dont plan a long bursts, but short bursts. Dont have a big yard. Just thought it would be kinda cool.

I was looking for a good dc motor, but just cant find one. AC motors are easy to find, but a good dc. It seems a golf cart motor would be great, but they are also like 36 to 48 volts. Just no room on a little cart for all those batteries, plus the weight. A starter motor is at least 12 volts and provides the needed torque.
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Old 01-09-2011, 09:04 PM
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Cool, give it a shot.
If you dont mind just having full power or off, you could skip using an expensive speed controller and just wire up one of these: http://www.northerntool.com/shop/too...ct_21065_21065 between the battery and your starter solenoid's small terminal that's labeled S .
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Old 01-09-2011, 09:08 PM
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In them videos as you can you got everything in the drill,like rev limit ect.I no your using a starter motor, this was just an idea thats all bud
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Old 01-10-2011, 05:01 AM
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Quote:
Originally Posted by toystory_4wd View Post

I was once told that as a rule, electric motors make their maximum torque at 0 RPM (ie starting), so therefore, yes. That's okay though, that's when you need it!
Yes, but I read that starter motors in perticular are wired in a different manner, which may give a big "jump" at starting out, not my cup of tea but its bearable.

That drill idea is....crude to say the least.

How would you plan to control the starter motor speed?
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Old 01-10-2011, 07:18 AM
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The drill thing is cute. When something breaks, unbolt the drill, and use it to fix what broke. Reminds me of a little thing I did a few years back- I trashpicked a Power Wheels z-71 Chevy pickup truck. Thrown out because the battery was done. I rewired the whole thing and made a little metal battery box to fit a DeWalt 18V drill battery as I have several. It worked well. Decent speed, and it would run 20-30 mins, even with both kids in it (2 seats). While they drove, I charged another battery- they could ride all day. They beat the wee out of it for a couple years before they outgrew it, then I gave it to my brother in law for my nephew to use.

I say give the starter motor a shot- sure it's not the best option, but before all the fancy scooter, wheelchair, and golf cart electrics came along, long before, they built karts with them.

Your biggest issue is the speed control. A simple, normal switch will not handle the current. A relay or high-amp swith will. BUT- going full on from zero with no variable control is a neck-snapping experience.
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Old 01-10-2011, 08:44 AM
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Quote:
Originally Posted by toystory_4wd View Post
A simple, normal switch will not handle the current. A relay or high-amp swith will.
Those push button switch instructions I gave above were to engage the starters solenoid (its already got a 500 amp relay built in) just like the cars ignition switch would. With using this method no additional relay would be needed.

I'll just add that GM starter solenoids can take up to 30 amps to engage, so you'd want to use 10 or 12 gauge wire size for the push button switch, and a minimum of 4 gauge battery cables to the solenoids big post and starters ground.
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Old 01-10-2011, 09:08 AM
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Yep- I agree- I pointed that out because some starters (Ford comes to mind) have remote solenoids, they were usually mounted on the inner fender well. If you have the starter only, this is a problem.
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Old 01-10-2011, 09:15 AM
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When you think about it, starter motors are a good source for 12 volt dc electric motors. Even if they are short lived, there are plenty at the junk yard.

I think I am going to give it a try. I was planning on a simple bar stool cart, with 3.5 engine, but if I can get this starter motor going I will bolt it on first.

I have a set of cam gear, 1:2, that are pretty hefty. Do you think that is a good gear ratio, or should I go higher? I am not sure what these motors put our or capable of.
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Old 01-10-2011, 09:39 AM
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Man, you've got me. I have no idea what "normal" RPM these starters tend to run at. If I had one, I'd tach it, so you can work the numbers from there.
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Old 01-10-2011, 01:15 PM
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This was mentioned before but how do you plan to cool it, generally they are not suppose to run for longer than 10seconds, needing at least 10 minutes to cool down standing, and will over heat in 20-30 seconds of constant run.
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Old 01-10-2011, 02:16 PM
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Well, honestly I dont have a huge yard and I am not planning on driving this to work. Yes, it will heat up, but maybe I can look for a way to provide some venting for it. I figure it will be an experiment, because I can always drop a 3.5 on the frame.

As far as overheating after thirty seconds.....I would be in the next county by then. I imagine only little jaunts up and down the drive way. Again, I believe it will be a novelty and experiment.

I've tried to crank my engine with a wrench and it does require a lot of torque to turn, with compression and everything. I will count the teeth on the starter and I have the old flywheel. The gear ratio is probably pretty high.
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