[sgtlethargic]

I'm looking for other ideas for motors. It seems like "back in the day" people used to use whatever surplus motors they could get their hands on for a good price. My application would be for a beach cruiser bike or a Honda Trail 90 (small motorcycle), or maybe a homebuilt minibike. To start off, would any car, truck, or such starter motor work well?

Thanks,
Kurt

 

[Woodsmith]

would any car, truck, or such starter motor work well?

Thanks,
Kurt

Would it work? Yes.
Would it work well? No.

Starter motors are designed to operate for a few seconds at a time. They generally don't have bearings, only bushes that are not suitable for high speed for any length of time.
They are also not designed to get hot, as their duty cycle is so low, and so running one will probably overheat it.

You best bet for finding motors is to look for motors that are actually used to run in a similar way to that needed in an EV.
That is why forklift motors are the usual low budget source.
Mine is from a milk float but it is serving the same purpose.

 

[major]

would any car, truck, or such starter motor work well?

Think about duty cycle. How often and for how long are you going to use the motor? And then the duty cycle of the application from which it came.

Starters, which are technically cranking motors, are designed to run intermittently, infrequently, for very brief periods at heavy overloads. In their intended applications, efficiency does not matter much at all, torque does.

So, in a nut shell, a cranking motor is a bad choice for EV propulsion. Overheating, low efficiency, noise, are an issue as well as bearings and output shafts as well as grounded frames.

But there are always exceptions to the rule. Some of those gear reduced cranking motors may not have all those issues, but they seem too small.

Regards,

major

 

[aegidius]

See if you can get a jet engine starter motor. They don't generate many volts/rpm and so may pull 1000's of amps, but they are very well made and super robust.

 

[Woodsmith]

Another source, apart from forklifts, is to look at the electric factory tugs.
Bradshaws for instance and old milkfloats if you had electric ones over there.

I would stick to motors that are designed to run for extended periods rather then very short duty cycles.

 

[nimblemotors]

car starting motors are not good. but for a small motor, there are other
cheap sources, look for pump motors, or winch motors, typically 12-24 volts. here is one:

http://cgi.ebay.com/ebaymotors/New-...ptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

I'm looking for other ideas for motors. It seems like "back in the day" people used to use whatever surplus motors they could get their hands on for a good price. My application would be for a beach cruiser bike or a Honda Trail 90 (small motorcycle), or maybe a homebuilt minibike. To start off, would any car, truck, or such starter motor work well?

Thanks,
Kurt

 

[major]

car starting motors are not good. but for a small motor, there are other
cheap sources, look for pump motors, or winch motors, typically 12-24 volts. here is one:

http://cgi.ebay.com/ebaymotors/New-...ptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

This is barely better than an automotive cranking motor. Intermittent duty, grounded, sucky efficiency, but does have ball bearings and decent output shaft. It is a poor EV choice, even for a bike or kart

 

[Automcdonough]

alternators are a better choice. Can use BLDC or induction controller, have to add a little extra to control rotor field voltage. But they are good at running w/ load full duty cycle.. a few truck alternators would certainly push a motorcycle.

 

[mechman600]

At first I agreed with all the replies. But then I started thinking: a truck cranking motor could be made to work. I work in the shop at a dealership and I am chucking broken starters all the time. 99% of the failures are in the solenoid, which wouldn't be used in our application anyway, as the controller would do the switching.

Now for theoretical numbers. An HD truck has 4X 900CCA batteries in parallel. So let's say 900A X 4 = 3600A. Remember, there is not controller limiting amps here. The original BANG when you hit the key and the solenoid closes is potentially drawing >3000 amps for a split second. During cranking, the engine is typically turning 300 RPM and the starter draws ~600A. 600A X 11V = 6600W. These numbers may be a bit low, as the Delco 44MT can deliver 8.5KW, according to their propaganda. And that's only at 12 volts! http://www.delcoremy.com/Starters/Models/44MT-Heavy-Duty-Starter.aspx
I am throwing these figures out there just to emphasize how strong they really are built - the amps they can handle in short bursts is amazing.
The tail end of the starter has a ball bearing, I know that. The drive end has a bushing. This would have to be retrofitted to ball bearing, but the "Bendix" drive end would have to be removed and a shaft + sprocket installed to make it useful to us anyway. Also, a starter is not designed to dissipate heat. It has a huge heavy case made to keep foreign things out. If we stripped it down and took lots of case material out in between the 4 field windings so air could get in and out and to lighten it up a bunch, maybe we could increase the duty cycle with a bit of heat rejection. Also, if we only gave the motor 200 amps as a limit, maybe it could go a while before burning up. 200A X 48V = 9600W - not too shabby. Oh, and FYI, the case is NOT grounded on these starters. It has an insulated ground stud.
If you have a controller and battery pack and want to play around, just go to any Peterbilt or Kenworth (etc.) dealer and ask a parts guy if you can buy a Delco 44MT starter core off of them. I'm sure it wouldn't be more than $30-50. If you're in the Vancouver area, maybe I can hook you up for nothing. Add a few hours of your time and who knows, we may be on to something here. Or, maybe we're nuts and nothing more.

 

[Woodsmith]

Why not give it a go and see how it works? I mean that seriously. If you work with them then you will have access to them adn the equipement to rework them. You never know, you might find that in amongst all the wrong types there is a right type that converts easily and gives a reasonable return.

Be careful of removing metal from the frame though, often it is designed that way as a means of providing a path for the magnetic field. If you remove metal then that may change the field and result in a loss of performance.

However, bare in mind that what you are proposing is to convert a truck starter motor into a different kind of motor for a different use.
It might be cheaper and easier to buy an equivelent output motor designed for the job.

It is a bit like trying to convert a large motor bike ICE to run a truck. Bore it out for bigger pistons, regrind the crank to increase the throw for more torque, add a water jacket to improve cooling, change the oil pump for higher pressure, rework the cylinder head to include diesel injectors....

Sure it will sorta work but it would be easier, and saves money on the development work, to just buy a small truck engine.

But, if Cedric Lynch managed to scratch build an axial flux motor, using flattened tin cans, for a race project and have it develop into the Agni 95R then why not you. Only one way to find out.

 

[major]

Also, if we only gave the motor 200 amps as a limit, maybe it could go a while before burning up. 200A X 48V = 9600W - not too shabby.

That might be 20,000 RPM for that armature

 

[gottdi]

Why not use an old Tractor or Truck Generator. You know those things they used to use before alternators became all the rage. They have an excellent duty cycle as they are being used all the time, They have bearings, and they last for just about forever. My Generator from my old VW spins up great with some power attached. Granted they are generators but what the heck, Cheap and easy to find. Should not be too hard to advance the brush ring. Many only have two brushes but for fun they'd sure beat the starters. Or modify the starter armature and fields into the generator body and have a stronger motor. Food for thought.

Pete

 

[DIYguy]

What about DC generators? Like maybe using one out of an old electric generator welder? Lincoln or Horbart "Torpedo" welders....

 

[mechman600]

That might be 20,000 RPM for that armature

I bet you're right. At 12V and 600 A it's spinning ~2500 rpm already. Scratch that...I'm changing my tune again. A starter is a dumb idea.

 

[todayican]

Ive been thinking about winch motors as well lately

How do you guys think one would hold up 2 to 10 minutes at a time?
Ive been toying with the idea of using a simple contactor controller to replace "1st gear" in a hybrid trike im building, this would allow me to use a much smaller ICE , gear it lower, and not worry about the clutch on the ice so much.

 

[nimblemotors]

well, they don't cost much, test one out. They should be OK, particularly if you have some cooling, normally a winch doesn't move and have airflow to cool the motor, but it could in a moving vehicle.

 

[Automcdonough]

For a bicycle i think a little motor like this would be great. It only takes 100W or so to cruise.