AC Motor as starter motor for a listerl(oid) ?

[veggie]

Has anyone used an AC electric motor as a starter for your Lister(oid) ?

If I put a 3" pulley on my 3/4HP, 1800 rpm 120 volt AC electric motor and belt drive to the 20" flywheel it would
theoretically turn the Listeroid at 268 rpm for starting. (20" flywheel / 3" Motor pulley = 6.7:1 ratio).
The challenge would be to kill the AC power to the motor as soon as the engine fires.
My concern is that the moment the engine starts and picks up speed it will overspeed the electric motor before the AC power is disengaged.
I am not so concerned about a momentary back feed but I do wonder if the motor would be damaged by any reverse currents?

This video appears to be using an AC electric motor as a starter. They show it at the 1:00 minute mark.
https://www.youtube.com/watch?v=SbqWkVC84bQ

And can a motor handle free spinning at 4000 rpm once the motor starts and speeds up to 626 rpm.
625 rpm engine X 6.7 ratio = 4187 rpm motor

Any advice or experiences with this method ?

Veggie

[BruceM]

Hi Veggie,

That poor Listeroid in the video is so badly out of balance it's pounding itself to pieces.
A serious cruelty, it should be a crime.

An induction motor is a bad match for a starter, low starting torque and huge locked rotor current.
If it's free  and you really want to see it for yourself, just disconnect power manually when it begins to start to stop it from becoming a synchronous generator. You can do that by rpm sensor (I like the cherry hall effect gear tooth sensor for counting my spokes) and an Arduino Nano to do the disconnect automatically.  Or a thousand other ways...

Best Wishes,
Bruce

[veggie]

Thanks BruceM,

Ok, I will toss that idea.
I am also a bit cautious about spinning an 1800 rpm motor over 4000 rpm once the system is running,

The reason I am looking at stater alternatives is because my golf cart starter/generator died after limited use.
I suspect it too had issues with spinning the heavy flywheels up to speed and pushing through compression stokes.

There is a Gast 4AM air motor with a rubber friction wheel in my inventory, so air starting is a possibility. But that thing uses a LOT of air. I don't really have space for a dedicated starting air receiver tank... but perhaps I can make it work.

[Powdermonkey]

Well....it would seem to me that a bendix starter coupler could be rigged up.  The question is whether the AC motor could develop the necessary torque.  The 12V system works without a question.  Thus....a flex plate fashioned in some way SHOULD not be difficult. 

[BruceM]

I agree on the air usage issue Veggie.  I use the Gast 4AM as with rubber roller as starter.  It's been very durable. Air motors don't mind being stalled with huge starting loads. It does use lots of air once it does spin up, which isn't a problem for my shop's 500 gallon receiver tank. On a 30 gallon tank I can get 2-3 starts.  My Lister's primary function is running an air compressor for my shop, and now inverter backup AC power.

I always appreciated your use of the starter/generator. How long did your starter/generator last?  How did it fail?

I killed one (surplus) GAST 4AM  motor myself- water in the compressed air system corroded it badly.  I have since added a big water separator unit and a drain on the line going up the hill in a trench which used to catch condensate and then gravity feed the water back to the engine shed air starter system, overfilling and overwhelming my former standard sized water separator.  Sometimes you can learn a lot from a failure. 

[veggie]

How long did your starter/generator last?  How did it fail?

It lasted for 9 years (not sure how many hours or starts).
Not sure how it failed. No magic smoke, just quietly stopped. I am looking into testing procedures and perhaps when I disassemble it the repair may be simple. At the moment I am hand cranking the engine. For the longer term I think the answer will be AIR or a repaired Starter/Generator. Both of those solution will be easier that me trying to adapt a flex plate (ring gear) to the Lister crankshaft. An automotive starter would be very nice, especially for automated starting, but it's more work that I want to invest at this point.

Cheers
veggie

[BruceM]

Veggie, I hope your starter/generator autopsy/repair of the starter will prove fruitful. Nine years is pretty good.  I hope it's just a bum wire connection and not a cooked open winding.

I'm still on my original rubber roller from McMasters. No appreciable wear, and thousands of starts and 15 years or so.  I appreciate the mechanical simplicity of the rubber wheel, friction drive.  I've seen some really nicely built starters shown here with a rubber roller on an automotive starter motor.

[veggie]

Thanks BruceM,
And yes, I found the issue. basically time and entropy were the culprits. 
A corroded screwed connection where the power lug passed through the starter casing.
I cleaned + bench tested the starter and it worked fine again.
After that was fixed more corroded connections were found at the battery terminal. Then, a quick test of the battery showed that it was shot.
I am not too surprised after 9 years of use, and the fact that the battery was a "take off" from my vehicle after 6 years of prior use.
On this assembly I coated the connections on the new (used) battery as well as the starter solenoid to help prevent corrosion.

cheers,
veggie

[BruceM]

Fantastic post mortem results Veggie ! Glad to see your 12V starter motor/generator vindicated, I have always thought it was a great setup you had. 

Next time you'll know to do an anti-corrosion plus wear and lubrication service on the motor/generator when you replace the battery.