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Using a forklift motor, and choosing a good one

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#2,561 ·
Dan Frederiksen said:
it's my impression that you can in principle feed them any voltage. it's not like a 24V motor will melt if you feed it 36V. volt in principle can't hurt it BUT volt motivates current to appear. the higher voltage the more current will tend to appear and current can destroy a motor. to really understand it you have to understand the physics concept of work. nature has a magical way of ensuring you pay for the work a motor does. work is the force (or torque) applied over a distance. if you apply force and nothing moves you don't have to pay for it. just like a paper weight is free force. that force (or torque in the case of a motor which is just force going in circles) comes from the current and the work done during rotation is paid for with voltage. you can imagine a worker that only does as you pay him.
this means for instance if the motor is stalled, let's say up against a wall and can't turn even a little voltage will make the current rise a lot because there is no rotation and no work done. you pay voltage and it tries to make work. when it can't the current rises dramatically, in theory infinitely if it weren't for resistance in the wires. but going 100km/h it wants a lot of voltage to maintain a current level. if you don't feed it the current will drop to the level you feed it. nature has a 'magical' way to make sure you get exactly what you pay for.
so voltage motivates current in a balance with how much work the motor does. slow rpm it's easy to motivate current to appear. high rpm it takes more voltage.
a motor's limit is a current limit and not a voltage limit BUT there is an indirect voltage limit because the motor can only handle so high an rpm for mechanical reasons.
let's say a motor is rated at 150A continuous and 5000rpm and that at that speed it takes say 100V to keep the current level at 150A. so you might say that 100V is the max for that motor BUT a motor can take more current briefly so let's say you want it to peak up to 450A then you need 300V to keep that level at 5000rpm. that would be 450Ax300V=135kW (or around 150HP after efficiency)
the power formula you can use is

P = T x w = T x Hz x 2 x Pi where T is torque, w is rotational speed in radians per second, Hz is revolutions per second, Pi is 3.1415...

torque is a direct result of current in the motor and that relationship you can look up in a spec sheet for the motor. a current torque graph (not always available) here are some example curves: http://www.zev.dk/misc/torque-curves.gif

once you have that for your motor you can use the above formula to roughly figure out how much voltage your desired performance will take at the motor's max rpm. it gives you a power value for your chosen current which you can then get voltage from using

P = I x V

where I is current and V is voltage. P is power.

IIRC :)
Click to expand...
This is awesome! I’m going to throw this formula into an excel page and noodle around with it to see what motor/battery combo I need for my
‘65 beetle to go 70-80mph briefly but be able to cruise at 60 or less for a 100 mile range
 
#2,562 ·
Ian J. said:
This is awesome! I’m going to throw this formula into an excel page and noodle around with it to see what motor/battery combo I need for my
‘65 beetle to go 70-80mph briefly but be able to cruise at 60 or less for a 100 mile range
Click to expand...
Something to bear in mind is that the current limit is time related
My motor is "rated" at 200 amps - that is the one hour rating - basically it will not overheat at 200 amps
HOWEVER that is at about 1400rpm - at say 4200rpm the built in fan is putting a lot more air through the motor

AND - an hour is a long time

In my car I feed that motor with 1200 amps - and it survives as I can only feed it for a few seconds before I have to lift off

I'm running a 340 volt battery
 
#2,563 ·
Dear all in this amazing site,

Greetings and congrats to all those who who have posted. Every point of view is information for others like me who have been tested positive on "I want to build / convert an EV".

I have the chance to purchase 3 different motors from one forklift (see attached photos) for $250, ready for collection.

If I get these motors, what would be the "sweet" conversion voltage to run them and how heavy can the total build be? Planning a budget conversion and keeping the shift transmission.

Any reviews / replies appreciated.

Cheers, Tommy

PS: The second motor is rated at 180 amps, as the photo is not clear...

PPS: any suggestions for a Siamese layout before the tranny are welcome (Space issues discussed later)


122131


122132


122133
 
#2,565 ·
Hello again,

This time I have the chance to get a Motor with the same specs as the motor in the attached photo.

(I hope the original poster of the image does not mind me using it).

The "No E 534671" is different, the rest is the same.

Any pros and cons? What would be a reasonable price to pay for it?

Any input from the members out there is very welcome :) (y)

cheers, Tommy

122348
 
#2,566 ·
Tommy McL said:
This time I have the chance to get a Motor with the same specs as the motor in the attached photo...
Click to expand...
That's not a "forklift" motor, or a brushed series-wound DC motor (which is what people usually mean by "forklift" motor). This isn't the thread to discuss it. Why not post a separate thread (in this same section of the forum)?

In your new post, mention that is a Siemens 1PV5135-4WS14; there is lots of experience with them. Or just search the forum for "1PV5135-4WS14".
 
#2,567 ·
Oops...

what brian_ mentioned is correct. Many thanks. Also thanks for the suggestion.

If a Forum Administrator can relocate my post, I would be thankful. No point in complicating this thread.
 
#2,568 ·
Tommy McL said:
If a Forum Administrator can relocate my post, I would be thankful. No point in complicating this thread.
Click to expand...
Good idea, but there is no longer any active forum administration. It would be easier to just create a new thread, and perhaps edit out the contents of the posts in this thread (since members can't delete even their own posts in the current forum software).
 
#2,570 ·
Hi Torque Electric said:
Actually just the opposite, being they are wound a little courser (heavier wire and less turns) and in general will have a higher RPM at "X" current when compared to the basic "EV" produced motors. As for the stated 3500 RPM's that's determined by voltage and load on the motor and also in general is a decent sweet spot RPM (3K to 4.5K) for a lot of motors.

I've seen and built a number of converted lift motors and they do nicely. It's not EVeryone's cup of tea but for those you are under a budget and are handy with tooling it can be a great way to get a drive motor. Shafts and adapting the motor are the biggest issues when compared to motors that have adaptor plates already designed and available. You usually have to advance the brush timing on these motors (where as the ADC's and Warp's are already advanced) for a higher voltage.

As I posted in another thread any data tag that maybe on the motor is just one point of refference and is usually a 1 hour or continuous duty cycle rating. By adding a blower and forced air cooling, the duty cycle can be increased quite a bit.

If we looked at Killacycles L91 motor for example (motors very close to it in a lift) would only be rated at maybe 48 volts and somewhere around 10 HP, where as Bill's stating around 325HP for the two of his L91's. There are actually a number of lift motors that are very close to, or verbatum to the popular EV motors being used, and with that said are diamonds in the rough just screaming for a new life as an EV drive motor.

Hope this helps
Jim Husted
Hi-Torque Electric
http://www.hitorqueelectric.com
Click to expand...
I was thinking of using the transmission for it's torque conversion do you think that could make a difference in the size of the motor I know with electric vehicle you Don't need a transmission but I think gear ratios are defiantly valid when talking about efficiency in vehicles especially for toque
Hi Torque Electric said:
Hey all

I thought I'd chime in and discuss the basics on choosing a forklift motor. In general, I advise people to look for a motor that weighs between 100 to 150 lbs. The heavier the car, the heavier the motor needs to be to push it around. The way I see it is, you don't want Peewee hermin trying to pull you around but you probably don't want to feed Hulk Hogan either, lol.

When searching for cores, look for insulation that is wine colored with yellow banding, brush leads that are still copper color and not scortched, and a commutator that isn't grooved or pitted. Don't be afraid to remove the cover band and have a look inside the motor (and while you're there take a pic to send me). I get a lot of "I wish I had wrote you before I bought this emails" and it's a bummer to read them honestly. I'd bet that almost half the motors I've built are still not up and running yet, so you might not need that motor as fast as you think you might. Sometimes looking to eager to buy not only drives the price up but might also cause you to buy something ill suited for your needs to boot.

Look for armatures that have a commutator with a large bar count as the larger the bar count the higher the voltage it'll take. Also, look for solid field leads (if you're looking for a series motor) or you might end up with a sep-ex or compound wound motor that may not suit your needs. Shafts can be one of the biggest issues in using a lift motor so make sure the shaft is something you think you can attach to or modify. There are motors I reshaft, but there are others that aren't as easy to do, or have no "standard" useable replacement shaft avaiable and then you're looking at needing a custon shaft made which makes them cost prohibitive.

Choosing the right motor isn't rocket science (unless you're a racer, hehe) but does need a little thought thrown at it so the end results are rewarding and meet your needs.

Happy hunting

Jim Husted
Hi-Torque Electric
http://www.hitorqueelectric.com
Click to expand...
I thought about just boring out the crank shaft and turning it there. would that work? I would remove the gas lines and spark plugs then try to turn the cylinders into a big electric air pump, but if I'm turning the crankshaft that will convert the torque for me so I shouldn't have to do anything else with the engine correct?
 
#2,571 ·
XxGrimlyxX said:
I was thinking of using the transmission for it's torque conversion do you think that could make a difference in the size of the motor I know with electric vehicle you Don't need a transmission but I think gear ratios are defiantly valid when talking about efficiency in vehicles especially for toque

I thought about just boring out the crank shaft and turning it there. would that work? I would remove the gas lines and spark plugs then try to turn the cylinders into a big electric air pump, but if I'm turning the crankshaft that will convert the torque for me so I shouldn't have to do anything else with the engine correct?
Click to expand...
I intend to connect to the transmission shaft using the center of an old clutch plate pressed into a machined hollow shaft .I usually can do this by heating the hollow shaft to 400 deg in an oven so it expands, rather using a press. The shaft will have to be machined to fit the motor if I cant find a suitable shaft,
 
#2,579 ·
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