I think you're right.

 

Sorry, to have had an opinion. From my point of view, its better to explain why some thing is not going to work and why, so it doesn't discourage a person, especially a young person, when it doesn't. He was talking about getting more than 10MPH. A wiper motor is at best only a 1/2HP motor and I doubt that 10MPH is possible.

 

I have no idea what 1/2 HP can do. Half a horse seems like a lot of power to me.
That's about 370 watts. My ebike uses a 250W motor and I can do 20mph (32km/h) (a regulation limit, not max).

There are too many variables. Power source, weight, friction, gear ratio.
The best way is to try it out and find out. That is what inventors do.

 

For more discusion , put starter motor in find box, upper right, this page.

 

I guess its because I have used wiper motors to make things. The motor its self runs ~10,000Rpm, then a worm gear set into a double pinion gear reduction. All of the gears except for the worm(which is actually made from the motor shaft) are nylon or plastic and at best 1/4 inch wide.

Every one says to stay away from starter motors because they have bronze bushings on the shaft, well so does the wiper motor that now is the "way to go".

As far as saying a starter motor draws too much current, that is only because of the load on it. Its capable of handling that much, but in a low load like a go cart it won't pull more current than it needs to move at speed. A free running starter motor only uses ~ 20A. Same as the wiper.
After the cart is moving the amperage use is going to be fairly small.

A starter from a car made after the mid 1980s is not the same as the older style. Instead of a wound field they are now permanent magnet motors. So even less of a current load. Some of the newer ones are even ball bearing motors.

Like I said earlier the wiper motor is only around 45RPM on high speed, using these calculators you can plug in the numbers to get the speed of the cart- http://www.diygokarts.com/vb/showthread.php?t=9591

 

For a while I was working on building an electric bike using a starter motor, but it is not the best choice for that sort of thing. Starter motors are not intended to be on for more than 10 seconds at a time, and if they are left on, they will very likely overheat. They also draw a LOT of current, so your battery would die very quickly. You won't be able to just connect the alternator to recharge the battery, as that would be, as strantor said, an overunity device. I really wouldn't recommend using starter motors. I'd lean more towards power chair motors/batteries. You might be able to find some on ebay. They are designed to be left on for extended periods of time.

 

One other thing I contamplated while researching for my gokart project is winch motors. Those offroad winches have some pretty beefy motors on them, some 2, 3, and 4HP. You can find the replacement (cheap, chinese) motors for them on amazon.com for relatively cheap. I don't know if they are continuous duty cycle, but I think their duty cycle is a lot better than a starter. example

 

A starter from a car made after the mid 1980s is not the same as the older style. Instead of a wound field they are now permanent magnet motors. So even less of a current load. Some of the newer ones are even ball bearing motors.

Thanks, I didn't know that. Any idea why they changed it? It seems like the perfect application for wound motor. I thought Permanent magnet motors are generally not good in hot environments because of demagnetization.

 

Thanks, I didn't know that. Any idea why they changed it? It seems like the perfect application for wound motor. I thought Permanent magnet motors are generally not good in hot environments because of demagnetization.

The reason was mainly weight reduction. Magnets are lighter than copper and iron for the fields. They are "ceramic" magnets not neodymium. Ceramic magnets are nearly temperature critical as neo. Almost all of the industrial DC motors use ceramic, both because of cost and heat resistance.


As far as a starter motor and heat, while they will get hot by continuous use as a starter, when used for other things not so much. People that post and say they do have just never used one. (Internet myth) No more than any other motor. They only draw as much current as needed to fit the load. Just because they can handle 100-200A doesn't mean they draw that much with a light load. They are designed for worse case loads. As a starter they see a high load, in any other application not so much.

The early snow plow lift pumps and Warn winches used a Ford starter motor. In my off-roading days I couldn't afford a Warn winch, so I hunted the scrap yards and found a piece of farm equipment that had a double worm gear reducer on it. (the first worm wheel feeding the second worm gear.) And made a drum and frame to make a winch. Used a Ford starter to power it. For reversing it I insulated the internal wiring from ground and used four starter switches(some call them solenoids but the are really starter switches)

The reason Ford starters are used is because they just use a Bendix drive and no drive solenoid, like GM. Never once Had a problem with over heating, motor or switches. And that winch got many long work outs.

I think I still have plans from an old Popular Mechanics magazine for making a starter powered cart. And I know I have the plans from a PM book to make a hand grinder and drill from starter motors. I'll scan and post if any ones interested.

 

I think the OP has moved on to gas engines, but a starter motor makes sense, as they are designed for hi torque at times. Without a good drivetrain, I think most electric motors would really struggle to start a go-kart from a dead stop or overcome a small hill. I still think it would get wicked hot going up a bigger hill, drawing 100A for, say, 2 minutes straight. That'd turn it into a 1200W heater.

FWIW, the Tour de France guys average almost 30mph while producing well under 1/2hp, maybe only 1/4hp at the wheels of their bikes.

 

Ceramic magnets are nearly temperature critical as neo.

Can I assume you mean Ceramic magnets are not nearly temperature critical as neo?

As far as a starter motor and heat, while they will get hot by continuous use as a starter, when used for other things not so much. People that post and say they do have just never used one. (Internet myth) No more than any other motor. .

I was referring not so much to self-heating, but all the heat under the hood. On some cars the starter is spooning with the engine block on one side, with exhaust on the other side. That's a pretty hot environment. I guess not hot enough to matter though.

Good info about the ford starters. Maybe I'll start looking into this again. And yes, if you have nothing better to do, I'd be interested in seeing those articles.

Thanks,

 

Hello Tyrone,

I guess I will chime in since I am working a similar project (electric rideable cooler). I guess it all depends on your budget on what you want to make and what performance you want. I maybe repeating a lot of what has been said so pardon me if I do.

I am using some simple AGM 12V 12Ah batteries that you can get on amazon for about $23 a pop ( I am using 3 of them). These are not really deep discharge but since they are pretty cheap I might ride them a little harder then I should. You can get various voltage and Ah ratings for marine and other deep discharge batteries (batteries you can basically fully discharge).

The motors I have been looking at are for electric scooter and pocket bikes. There are various sites for this but I am going with either the 1000W or 750W model. They are < $100 and are chain or belt drives depending on power. Doing the calculations on various sites I will get some pretty good performance out of it. At 3000 RPM and 4:1 gear ratio and 10" tires, I am predicting a speed of almost 22 mph. This is no load (weight) so I will have to do that calculation (myself plus fuller cooler plus frame = 300 lbs). You can all see other riding coolers that are rated at 1000W being able to almost lift the front end off the ground.

I am making my own H-bridge but there are plenty of market controllers that aren't bad. If I bought everything out the door for the electronics it would probably be $300-$400 I would guess.

Good luck on the go kart and I hope you let everyone know how it turns out. I hope this gives you a few more options and configurations to consider.

 

@Strantor - Since the OP seems to be gone, I won't start a new thread for these scanned pages. From the Aug. 1963 Popular Mechanics. Not the plans I was thinking of but the ones I found, too much stuff and no organization.

 

And heres the rest of them. If you want I'll keep looking for the grinder and drill.

 

You could have saved some work and just gone here.

Maybe you can let go of some of the "stuff" now?

 

And heres the rest of them. If you want I'll keep looking for the grinder and drill.

It's ok, I was hoping there would be some data on the motor itself, but I predict it will be more about how to build the device. I appreciate you taking the time to find that for me.

 

Shortbus,
is this the one you're talking about?

 

I wonder if I can still get the 22" x 30" full size drawings and instructions from Popular Mechanics for $3.50???

 

@wayneh- I have got rid of a lot The magazines were my grandpa and great grandpa's. Used to spend hours at a time reading them when very young.

@ strantor- Thats the one, But I have it from a Pop Mech book on tool making.

The world sure was a different place back then. People made stuff instead of buying it. A magazine like those wouldn't survive today, now they are basically catalogs instead of how to do .

 

The world sure was a different place back then.

True dat.

People made stuff instead of buying it. A magazine like those wouldn't survive today

Maybe not a magazine (Make is still alive?), but there sure is a lot of whacky stuff going on at Instructables, on YouTube, and so on. But it does all seem to be far outside the mainstream, which is more obsessed with drunken teenagers and "reality" TV.