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Discussion Starter · #1 ·
I've been working on converting a '78 Fiat 124 spider to electric, and I wanted to get some opinions (I don't think any of these questions have clear cut answers given the limited information I'm giving, but I'm hoping someone has similar experience and can give some pointers):

I recently picked up a used Hyster forklift motor (from a J40XMT). It weights ~80lbs, is 8" in diameter, and the main portion (not including the shaft) is 10" long. Question 1 is: do you think this is big enough? It looks a tad small. Has anyone used a similar motor? I'm expecting the car to come in around 2300 lbs finished, with batteries:

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Second question: I just realized it doesn't have a bearing in the front. I assume the gearbox in the original forklift supported the front shaft. If I turn it by hand, the rotor rubs against the sides (there is a bearing in the back):

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I'm thinking that, once I get the shafts coupled, the transmission bearing may be able to support the front of the rotor and keep it aligned, but curious if anyone else has used a similar configuration or has thoughts.

Thanks!
 

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Discussion Starter · #5 ·
There you go, a bit under 8HP at 48v. Say you were to double the voltage, that will be 16HP. Enough for a Golf cart, but not much else.
Okay, I'm learning things. :)

The thing that made me think it's a drive motor is that it's series wound (that is, it has four terminals: two for the armature and two for the field), and most pump motors don't seem to be.

I was planning to run it at 120v, which would be around 20hp, but, what I've read is that horsepower ratings are less important for electric motors vs. an ICE engine, because they produce much more torque at the low end. I'm curious what kind of rating is worth looking for on one of these motors (I did read the uber thread "Using a forklift motor, and choosing a good one", but I didn't see much about ratings in there, it seems to mostly talk about size and weight).
 

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Discussion Starter · #7 · (Edited)

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Horsepower determines vehicle speed and the torque/speed through the transmission.

You betcha HP's important...unless you plan to take the trunk lid off to fit golf clubs vertically into it.
 

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Discussion Starter · #9 · (Edited)
Horsepower determines vehicle speed and the torque/speed through the transmission.

You betcha HP's important...unless you plan to take the trunk lid off to fit golf clubs vertically into it.
Fair enough. I was never a very good golfer and don't have much interest any more in the sport. :)

It seems like all of the forklift motors I've seen list what appear to be pretty low numbers for power. And, since the manufacturers don't publish data sheets or detailed specs, it's hard to do the math, but a lot of people have figured this out empirically.

So, here's what I think I've understood from the elder EV builders who've come before (please feel free to disabuse me): The output KW field on the plate is the maximum sustained power it can output for 60 minutes straight (hence the S2 designation on the plate) without forfeiting the cost of a new motor. Most cars only require peak power while accelerating, and the motor can be driven well past this for short interval (10-15 seconds).

However, it sounds like what you are saying is that this is the absolute maximum power the motor will drive at a given voltage based on its series resistance and inductance/Kv, in which case, yeah, pbbbbbbth. (n)

If that is the case, what should I be looking for on the motor plate? The stock ICE motor in this car is ~90hp, which would be 67 kw. I haven't seen anything near that on any forklift motor plates.
 

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Forklift motors technically don't have to be all that crazy beefy, it all depends on the rating (max incline, top speed) of a given forklift. I have a brushed 7HP that came out of a 12,000lb machine (technically over 13,000 with lead-acid batteries). The machine is geared up such that the top speed is just about 5MPH.
 

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Discussion Starter · #11 ·
Forklift motors technically don't have to be all that crazy beefy, it all depends on the rating (max incline, top speed) of a given forklift. I have a brushed 7HP that came out of a 12,000lb machine (technically over 13,000 with lead-acid batteries). The machine is geared up such that the top speed is just about 5MPH.
So did you transplant that into a car (and how well did it work)? The plate for the forklift this came off of looks like a 9000lb machine. I'm trying to figure out if I still need to apply to join the local country club. :p


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@cricketo actually uses his forklifts for forklifting 😂 If I had a ginormous trailer and truck I'd be asking to borrow them 😈 Luckily for him, I don't 😉

Easiest way to put your finger in the air is if it's under 125 lb (an arbitrary ballpark number) it likely won't work in a car. Though your car is tiny...maybe go with a 9 inch forklift motor copy like a FB-4001 (iirc it's 140lb). There are others as well, though they are bigger and heavier. They aren't "free", though.

Though all of my current & upcoming builds are AC, high voltage, big HP, I have a Fiero that our 6 year old will build as her first car starting in a couple or three years (kid's got mechanical talent & skills) which will use the FB-4001 9 inch DC Brushed 144V DC setup. 30HP electric is plenty for a 16 year old. I've been picking up parts here and there as getting the pieces is half the timeline of a project unless you're scavenging a Tesla, Leaf, or other EV.

I'll have her do a build thread here when it starts up. Assuming I live that long and don't get banned by an organized snowflake protest in the meantime.

So, go by kW or weight. 8 or 10 kW isn't enough. You also seriously want to consider having regen if you live in hill or mountain country...a forklift or the FB won't.
 

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@cricketo actually uses his forklifts for forklifting 😂 If I had a ginormous trailer and truck I'd be asking to borrow them 😈 Luckily for him, I don't 😉
Well, yes - my forklift is used like a forklift. I posted the motor name plate in another thread recently, don't have it handy. Motor there is quite beefy, I want to say 14" in diameter, it's a 4000lb lift truck with total weight of 6000lb (going by memory).

But the 12k reference is to the boom lift. 7HP was the original motor controlled by Sevcon MOS90 that I replaced with HPEVS AC23 and Curtis specifically to let it negotiate steep driveway without burning out the MOS90 :D
 

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Discussion Starter · #14 ·
Easiest way to put your finger in the air is if it's under 125 lb (an arbitrary ballpark number) it likely won't work in a car. Though your car is tiny...maybe go with a 9 inch forklift motor copy like a FB-4001 (iirc it's 140lb). There are others as well, though they are bigger and heavier. They aren't "free", though.
Thanks, that's helpful. I do also have a LEAF motor, but that has a whole other set of challenges. I was hoping the forklift motor might simplify things, but I'll find something else to put it in. :)
 

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That motor is just a little bit too small - but the lack of a front bearing is a more important reason to ditch it - the bearing in your gearbox will NOT keep the armature centered well enough

Look for a 9 inch motor - but if you can find an 11 inch motor then you can ditch the gearbox completely and go direct drive to the diff

Power ratings - you will be running your motor at about 4 times the rpm in the forklift - this means that the "60 minute" power number can be multiplied by 4
The actual usage in a car - a few seconds before you lift off means that you can further multiply it

I'm putting 40 times the "rated power" through my motor - but I am a wee bit extreme
 

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Fair enough. I was never a very good golfer and don't have much interest any more in the sport. :)

It seems like all of the forklift motors I've seen list what appear to be pretty low numbers for power. And, since the manufacturers don't publish data sheets or detailed specs, it's hard to do the math, but a lot of people have figured this out empirically.

So, here's what I think I've understood from the elder EV builders who've come before (please feel free to disabuse me): The output KW field on the plate is the maximum sustained power it can output for 60 minutes straight (hence the S2 designation on the plate) without forfeiting the cost of a new motor. Most cars only require peak power while accelerating, and the motor can be driven well past this for short interval (10-15 seconds).

However, it sounds like what you are saying is that this is the absolute maximum power the motor will drive at a given voltage based on its series resistance and inductance/Kv, in which case, yeah, pbbbbbbth. (n)

If that is the case, what should I be looking for on the motor plate? The stock ICE motor in this car is ~90hp, which would be 67 kw. I haven't seen anything near that on any forklift motor plates.
I am also trying to work out what I am supposed to look for in a motor to power a 1000kg car...
 

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I am also trying to work out what I am supposed to look for in a motor to power a 1000kg car...
First answer is a question: what performance do you require? Is this golf cart speeds on a school property, do you need to do 6 seconds in the quarter mile, or somewhere in the middle?

Traditionally, one grabbed a used 11" diameter main series wound drive from a salvaged forklift, but that was before bldc.
 

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First answer is a question: what performance do you require? Is this golf cart speeds on a school property, do you need to do 6 seconds in the quarter mile, or somewhere in the middle?

Traditionally, one grabbed a used 11" diameter main series wound drive from a salvaged forklift, but that was before bldc.
I just need it to do 60-80kmh for 5 hours, every 2 weeks...
 
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