Finding a motor on a budget

286313 Views 173 Replies 62 Participants Last post by piotrsko, 5 mo ago

sukusia

Discussion Starter · Mar 26, 2011 (Edited)

So here is what I learned about motors from this site. I wanted to post a quick reference so newbs (like myself) do not have to sort through the sticky page.

When looking for a forklift motor:
Get a series wound motor because they have very high torque and handle abuse (over volting) a lot better.
Know the difference between a Spex motor and a Series wound.
When dealing with series wound forklift motors go for higher voltage. (36V may require advanced timing.)
Hp does not directly represent torque (although it does have a factor in its equation).
Get a class H insulation if possible (makes your motor last longer)
Get a motor around 150lbs (Wouldn't risk a motor that's too light, it won't have the oomph you need. a few extra pounds is A-o.k. but a significant amount of extra pounds limits your range)
Get one with a male shaft
A keyed shaft is easier to work with but you can still work with a spline shaft
Try and get the coupler that goes on to your motor when you buy it/rip it out (saves you $$ and time)
When looking for a different motor:
Ac is not the way to go for your first conversion (or do i just have low expectations of myself?)
You can tell if a motor is AC if it is a 1 phase or 3 phase motor
Pancake motors are usually not good candidates for car conversions. (Yeah you saw the one on ebay. They overheat easily)
Golfcart motors are seldom powerful enough for a conversion
Motors specifically made for EV conversions are the best but its gonna cost you.
You do have to look at many factor such as volts, amps (which gets you Hp). Torque is nice to know. Continuous Hp. So many factors!!!

"HP is HP Electric motors and gas engines are rated differently w/r/t HP. And they have different torque curves. But one HP from an electric motor shaft is exactly the same as one HP from a gas engine shaft at the same RPM "- Major

If there is any more helpful hints I'll be happy to add them

Reactions: 2

21 - 40 of 174 Posts

Vikingdad

· #21 · May 22, 2011

OK, I'm a Noob. I have an industrial electric motor that is rated at 10HP, 240V A/C 3 Phase. It weighs a heck of a lot, well over 100 lbs.

I also have a 10KW generator, again 3 phase and 240 volt. (This thing weighs a TON!!!!)

How would these two motors compare to one another and would either of them be suitable for an electric conversion powerplant?

major

· #22 · May 22, 2011

Vikingdad said:
OK, I'm a Noob. I have an industrial electric motor that is rated at 10HP, 240V A/C 3 Phase. It weighs a heck of a lot, well over 100 lbs.

I also have a 10KW generator, again 3 phase and 240 volt. (This thing weighs a TON!!!!)

How would these two motors compare to one another and would either of them be suitable for an electric conversion powerplant?

Hi Vik,

One is likely an induction motor and the other an alternator (synchronous machine). Neither would be a good choice for a rookie EV builder. AC motors require inverter type controllers typically costing more than DC converter controllers. Standard 240VAC machines mean battery pack voltage on the order of 300VDC. This increases the cell count, and cost of associated equipment for the battery like management and charger.

Regards,

major

hbthink

· #23 · Jun 30, 2011 (Edited)

Just made an ebay purchase of a 3-phase AC motor rated as following

Motor label specs:
Water cooled
keyed shaft dia=.75" x 2.6"
Torque 22.2Nm
Speed 4500rpm
Voltage 54.5
Current 136A

Hoping I can push the voltage higher and get enough torque for my 1800 lbs of 83 VW Rabbit. At least its water cooled, I thought that was worth the $500 purchase price. That shaft size and the fact that it is keyed much like my FB4001A is also nice

Steve

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DawidvC

· #24 · Jul 4, 2011

To see how much that motor can be overvolted, you need to know the voltage / frequency ratio of that motor. This can be calculated if you know what the base speed of the motor is. That should normally be the speed (in rpm) where the torque would start to fall off. Using that speed and knowing how many pole-pairs the motor has, would allow you to calculate the frequency needed to achieve base speed, and thence your v/f ratio.

Good luck with your build
Dawid

Spider-man

· #25 · Aug 5, 2011

I have seen a few people use aircraft starter motors in some conversions. Where do you obtain one of those?

cruisin

· #26 · Aug 5, 2011

Spider-man said:
I have seen a few people use aircraft starter motors in some conversions. Where do you obtain one of those?

Aircraft surplus stores near Oakland Airport Oakland, CA.

tropes

· #27 · Aug 7, 2011 (Edited)

So I just bought this rolling junior dragster and plan to convert it to electric. The motor that seems to fit is a 48 volt Brush-Type Permanent Magnet DC Motor from Electricmotorsport.com. The battery would be four
PC625 Odyssey drycell batteries. All my research says I should also buy a controllor. Can you tell me why I cannot just use an appropriate on-off switch to turn on the motor? Okay, so I checked around and found that there are no simple mechanical switch that won't weld contacts at this DC wattage. So what is the way to go?
Tropes

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Spider-man

· #28 · Aug 9, 2011

tropes said:
So I just bought this rolling junior dragster and plan to convert it to electric. The motor that seems to fit is a 48 volt Brush-Type Permanent Magnet DC Motor from Electricmotorsport.com. The battery would be four
PC625 Odyssey drycell batteries. All my research says I should also buy a controllor. Can you tell me why I cannot just use an appropriate on-off switch to turn on the motor? Okay, so I checked around and found that there are no simple mechanical switch that won't weld contacts at this DC wattage. So what is the way to go?
Tropes

The things I have seen mose is people will basically cut a normal section out of their main cable and add a plastic box and a handle to it. so that way it is like a giant removable section between the batteries and everything else for an emergency "kill switch" if you will. I saw a few people do it on youtube that way. I think the white zombie may be that way. I could be wrong tho...

G

· #29 · Aug 9, 2011

I have two. One connected to the old Kaylor adaptor plate for the VW. Sweet setup but best only for the lightweight buggy or kit car. Not for high speeds either but they do work. Can't over speed these puppies either. They may also make a nice DC generator for folks. I have some stuff on youtube too.

http://www.youtube.com/watch?v=2UtQuiiWAks

tropes

· #30 · Aug 9, 2011

Thanks guys. I think I'll keep looking.
tropes

ez2gonuts

· #31 · Aug 25, 2011

Is it possible to use a power converter to 110 ac and use a 110 electrict
motor

Jan

· #32 · Aug 26, 2011

ez2gonuts said:
Is it possible to use a power converter to 110 ac and use a 110 electrict
motor

If you mean with 'power converter' a regular 12Vdc to 110Vac inverter, I would guess: yes. BUT. They normally are not much higher rated than 1 kW maybe some up till 3 kW. Just enough to power a washing machine. Or a bike. But more important: How are you going to control the power? It's just on or off.

major

· #33 · Aug 26, 2011

ez2gonuts said:
Is it possible to use a power converter to 110 ac and use a 110 electrict
motor

Short answer....NO

I suppose you're talking about those 12VDC to 110VAC inverters sold to run AC stuff from your car battery. Those mostly are not sine wave and are single phase. For EV propulsion motor, you need 3 phase, and variable frequency on top of that.

Other issues also

major

Jan

· #34 · Aug 26, 2011

major said:
Short answer....NO

I suppose you're talking about those 12VDC to 110VAC inverters sold to run AC stuff from your car battery. Those mostly are not sine wave and are single phase. For EV propulsion motor, you need 3 phase, and variable frequency on top of that.

Other issues also

major

http://www.samlexamerica.com/products/productdescription.asp?ProductsID=20030

And there do exists single phase AC motors too. A lot.

Just to be wright for once.

Spider-man

· #35 · Aug 29, 2011

Jan said:
If you mean with 'power converter' a regular 12Vdc to 110Vac inverter, I would guess: yes. BUT. They normally are not much higher rated than 1 kW maybe some up till 3 kW. Just enough to power a washing machine. Or a bike. But more important: How are you going to control the power? It's just on or off.

I have actually done research on this. I have an AC motor that is rated at 1/2 hp. the max amps it will take is around 7 (I think) tops 8... so, as long as you buy a $70ish dollar inverter on the internet (capable of the max wattage of the motor for long periods of time) and couple it to a speed controller of some sort it should work. The "controller" would usually include a pot as well.

here is the one I am considering:
http://www.cshincorporated.com/product_info.php/cPath/122_39/products_id/138

good luck!

tropes

· #36 · Nov 11, 2011

When looking for a different motor:
Ac is not the way to go for your first conversion (or do i just have low expectations of myself?)
You can tell if a motor is AC if it is a 1 phase or 3 phase motor
Pancake motors are usually not good candidates for car conversions. (Yeah you saw the one on ebay. They overheat easily)
Golfcart motors are seldom powerful enough for a conversion
Motors specifically made for EV conversions are the best but its gonna cost you.
You do have to look at many factor such as volts, amps (which gets you Hp). Torque is nice to know. Continuous Hp. So many factors!!!
If there is any more helpful hints I'll be happy to add them

I have just purchased a slightly used K91- 4003, 72 volt motor for my junior dragster conversion. Is anyone here using this motor and if so, what are you using for battery, controller, throttle,contactor?
Tropes

Spider-man

· #37 · Nov 11, 2011

gottdi said:
I have two. One connected to the old Kaylor adaptor plate for the VW. Sweet setup but best only for the lightweight buggy or kit car. Not for high speeds either but they do work. Can't over speed these puppies either. They may also make a nice DC generator for folks. I have some stuff on youtube too.

http://www.youtube.com/watch?v=2UtQuiiWAks

What are the specs on the motor you are using gottdi?

EVfun

· #38 · Nov 26, 2011

Jan said:
And there do exists single phase AC motors too. A lot.

Just to be wright for once.

But can you find a single phase AC motor with anywhere near the peak power required for an on-road EV?

josmeijer

· #39 · Nov 27, 2011

EVfun said:
But can you find a single phase AC motor with anywhere near the peak power required for an on-road EV?

single phase AC motors are no option.
They have near-to-none starting couple while using up to 30 times nominal amperage until at their top-speed.
You should use triphase motors that are dumped 100 a day by industry so can be found on any scrapyard is all (k) wattages and speeds.
Next thing is to convert DC to triphase AC.

Inverter motor controllers (also industry standard, and easily obtained on ebay etc at reasonable prices) can be fed by DC
simply multiply the input voltage with 2 sqrt (roughly 1,4) and you have the required voltage.
So 110 v AC gives 162 DC volts.

Inverter motor controllers come in single-phase in / three-phase out that are rather popular.
They exist in up to 3 kw /220-240 volt in and >500 kw in threephase.

For more power you have to get three phase in/out types. These can be DC powered too, by paralleling the phases.
(first stage of any inverter controller rectifies the AC so phase is no issue, but you should check wit the manufacturer if this can be done without triggering some safety)

Yet the drawback is the high battery voltage but, as our soccer-idol Johan Cruyff says: "every disadvantage has it´s advantage" : you save many kilo´s of copper wiring and you might get a nice deal on small standard AGM batteries.

Finally,if you want to dig into it, most inverter controllers can do DC braking wich can be used to convert braking energy into battery power (instead of useless heat on your brakes).

But I must honestly say that all I state here remains theory for me.
I have lots of plans but all reside on paper until now.

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Weenam

· #40 · Feb 13, 2012

A query I have is finding a source for a forklift motor. Other than purchasing a wrecked forklift I have seen information about picking them up from servicing and repair places. However if a motor is being thrown out then surely it is not going to be worth salvaging for using in an electric car conversion. If it won't work in a forklift any more then to me it follows that it is only suitable as scrap. Please any advice gratefully received.

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