# Forklift motor for Thunderbird conversion



## major (Apr 4, 2008)

tostino said:


> I have a long commute of 40 highway miles each way, but I work 10 hour shifts, so I can charge at work for my return trip.
> 
> Any help would be greatly appreciated!


Hi tostino,

You'll have a very heavy EV by the time you put enough lead acid batteries in it to get that range and speed. I think you'll need the big motor with a bigger controller than that 72v, 400A Altrax.

Regards,

major


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## tostino (Jan 18, 2009)

major said:


> Hi tostino,
> 
> You'll have a very heavy EV by the time you put enough lead acid batteries in it to get that range and speed. I think you'll need the big motor with a bigger controller than that 72v, 400A Altrax.
> 
> ...


I was thinking that was the case... How fast do you think that altrax could get me? 
I made a spreadsheet to compare different battery brands and sizes (attached), and it looks like my batteries would weigh about 1980 pounds (for 21kwh of usable power including peukert effect).

What controller would you recommend me use? Is there anything in-between the altrax and something much more expensive?


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## Georgia Tech (Dec 5, 2008)

tostino said:


> The big motor spun at 2000 rpm no load with a 12v battery, and 3700 with 24 volts (155 k/v), and the little motor spun just over 600rpm with 12 volts (50 k/v). My question is, which would be better for the car conversion?


 
These numbers look a little funny...it seems as if the Bigger motor SHOULD have the lesser RPM per volt....But this may be due to the condition of the motors as well what were the currents while doing your 12 volt spin up?
Could be the winding construction and lam stack also though...just seems strange.....If these number are truely REAL, then I say look at the little one....but I think you got something going on here...


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## tostino (Jan 18, 2009)

Georgia Tech said:


> These numbers look a little funny...it seems as if the Bigger motor SHOULD have the lesser RPM per volt....But this may be due to the condition of the motors as well what were the currents while doing your 12 volt spin up?
> Could be the winding construction and lam stack also though...just seems strange.....If these number are truely REAL, then I say look at the little one....but I think you got something going on here...


honestly, I think so too. The numbers did seem odd, but I just am not sure what the average no load rpm for these types of motors are. I only have an ebike at the moment, and am working with brushless.

So you think the little motor is the messed up one?


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## Georgia Tech (Dec 5, 2008)

tostino said:


> So you think the little motor is the messed up one?


 
Well...I don't know it just Odd that the numbers came out that a way. I gues my first question is what was the current of each of the motors when you ran them at 12V?..there might be a short of some kind inthe little motor...Or this may just be a an Odd ball case where the bigger motor is a top end RPM runner and the 9 incher is the grunt....Can you describe the enternals of these two things? You do plan on takeing them a part and cleaning and makeing sure they are sound before using them right??? when you do post photos...that would spell alot of questions..


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## tostino (Jan 18, 2009)

Georgia Tech said:


> Well...I don't know it just Odd that the numbers came out that a way. I gues my first question is what was the current of each of the motors when you ran them at 12V?..there might be a short of some kind inthe little motor...Or this may just be a an Odd ball case where the bigger motor is a top end RPM runner and the 9 incher is the grunt....Can you describe the enternals of these two things? You do plan on takeing them a part and cleaning and makeing sure they are sound before using them right??? when you do post photos...that would spell alot of questions..


I didn't have an ammeter available when I did the test the other day, but I will be able to get one shortly. I do have photo's of the externals of each motor on my first post if that is what your talking about.

Yes, I do plan on taking apart these motors and cleaning them, and making sure everything works properly before I stick em in the car and let it rip.


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## major (Apr 4, 2008)

Georgia Tech said:


> ..it seems as if the Bigger motor SHOULD have the lesser RPM per volt.


Hey guys,

It doesn't make sense to try to use a RPM/volt constant for a series motor.

major


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## MalcolmB (Jun 10, 2008)

Does the no-load speed actually tell you anything about the characteristics of a series motor? I thought all it indicated was the physical resistance of the rotor, which is the sum of brush friction, bearing friction and air resistance.

It's still a bit odd that that the larger motor should have a higher no-load rpm, but doesn't that suggest a possible bearing problem or other mechanical problem (with the smaller motor)? Just for reference my 7.5 inch Prestolite has a no-load speed of 2200 rpm at 12V.


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## tostino (Jan 18, 2009)

Hrmm okay, I wasn't aware of the difference between PM/brushless and series wound (this is my first time trying to use one).


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## MalcolmB (Jun 10, 2008)

If you disengage the brush springs on the smaller motor and slide back the brushes a little from the commutator, then try turning the shaft by hand, you should be able to feel if the bearings are binding or if there's some other mechanical resistance.

Just going by size and weight alone it sounds as if the smaller motor would be the better bet for a medium-sized conversion. The bigger one sounds like a monster. I guess there's no rating plate information at all on either of them?


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## tostino (Jan 18, 2009)

Hey, yeah there is rating info, they are class "H"... other part numbers I can get for you later if that is actually needed.

I just went through the smaller motor and sanded the surface of the brushes (all messed up prior), and cleaned the commutator with electric motor cleaner, and took a screw driver to clean out the lines in it that were full of grease.

After doing all that, I spun it up on 12 volts, and it hit 2300 rpm. On 24 volts it was at 3800.

On both 12 and 24 volts, the motor was drawing 37 amps.

What other things will I need to do with this motor to get it ready for use in my car?

And also, what controller would you all recommend?


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## MalcolmB (Jun 10, 2008)

tostino said:


> What other things will I need to do with this motor to get it ready for use in my car?
> 
> And also, what controller would you all recommend?


Good to hear the little motor runs a bit freer after a cleanup! It's hard to say for sure whether either motor is suitable or what needs to be done to them without some more information. If you can get photos of the rating info or just post it here then someone may be able to give more advice.
By the way, you need to be careful testing a series motor under no load as once you get past a certain voltage they can just keep on speeding up until they fly apart. It's best to stick to 12V to be safe.

I just took a closer look and realised that a Thunderbird is quite a heavy car (1600-1700 kg?). Have you made up your mind that's the car you want or would you be willing to consider something lighter? It's like Major said, to get your 40 mile range you'll need a lot of batteries, which means even more weight and could mean the bigger motor would be the better choice. You could save a lot of money by going for a lighter donor.


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## slurryguy (Dec 16, 2008)

I am not an expert on motors.

However, I highly recommend that you read everything you can that Jim Husted has post on this message board. While I haven't put any of his advice to use yet, I've learned a great deal by reading his posts.

Use the forum search function from the menu.
When you click search, select "advanced search" and search by user name.

If you search for threads where the user "Hi Torque Electric" has posted, you'll learn a lot.

I also highly recommend digging through the narrated photo galleries that Jim has posted on his website.

Here is a good starting point:
http://hitorqueelectric.com/gallery/v/Step_by_step/

Note on the left side of that page, there are many other photo galleries.

You will probably want to advance the brush timing of whatever motor you choose. Jim describes the process well with his pictures, and in many of his posts on this forum.

My understanding is that Jim has been having some recent health problems, and hasn't been available much to help people with motors, but his personal library on the web is invaluable to those interested in doing exactly what you are trying to do.

Like I say... I'm no expert... so I like to read and learn from the people that are experts, like Jim.

I hope this helps...


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