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Discussion Starter · #1 ·
So, I haven't posted In a while because my electric boat project stalled and I have been working like a mule but .. . .

The motor recently blew on my farm truck and since I already had a drive motor taking up space I've decided to do a conversion. I'll post the build in a different forum.

This is the motor I'm using, It's a bit on the big side but I already have it and it's light compared to the cast iron engine I pulled out - and It will fit.the space just fine.

This motor has a cooling fan which has it's own drive. I'm wondering if anyone is familiar with this and could give me any pointers on how it's powered. It has a three prong plug and I'm unclear how it should be hooked up. Not sure if one is neutral and the other two are low/high I'm planning on spinning the fan and poking the plug with a volt meter to see what that shows but I'd love a little guidance.

also there is what appears to be a signal wire on the other end of the motor if anyone has a clue what that is for.
 

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Some fans have a 3 wire interface: ground, power positive and tachometer signal. You can probably isolate the tach wire by trying to spin the fan with compressed air and measuring frequency on the pair of wires. Although if the tachometer sensor is an active kind like Hall, the fan may need to be powered too :(

The other connector is likely going to some thermistors for temperature monitoring. You should be able to isolate those by checking the resistance, which should go into several kohms. It is also possible that there is another tach for the motor itself.
 

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Is it a Series or a Sepex motor? case length and diameter? Weight? Some interior shots of the windings, commutator, and brushes would be helpful to evaluate the motor.

Also, pictures, type(s), and dimensions of the output shaft(s) would be good info to have.

What is the vehicle you want to put this in?
 

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Will running 11kW for a max of 15 minutes get you to the grocery store? Seems awfully underpowered for a truck.
Since the 11 kW rating is at 48 volts I assume that the plan would be to run it at higher voltage, like all the rest of the "forklift" (or other industrial brushed series DC) motor conversions. It still won't handle the sustained power that the original engine could provide, of course. Average power use of even just 11 kW might be adequate for the truck at moderate speed.
 

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Again, it doesn't matter what voltage you run at, the magic smoke starts coming out after 15 sec at 11kW according to the nameplate.

11kW is your 0-30mph sprint with it floored. Getting a TRUCK to 50 on 11kW is a stretch, don't you think? And you can only run it there (say you start off on a hill) for 15sec.

I would not push that motor's output without a thermocouple monitoring winding temperature. I'd also add a cooling jacket to it.
 

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Again, it doesn't matter what voltage you run at, the magic smoke starts coming out after 15 sec at 11kW according to the nameplate.
It's not that simple. The rating is probably based on heating due to current; the same current at higher speed (which requires higher voltage) may result in acceptable heating.

11kW is your 0-30mph sprint with it floored. Getting a TRUCK to 50 on 11kW is a stretch, don't you think? And you can only run it there (say you start off on a hill) for 15sec.
No, with higher voltage the power for that sprint will be higher... as it certainly needs to be for performance that most of us would consider acceptable.

I have no idea what the truck is (maybe it's a little old Ranger), but yes, 50 MPH on 11 kW seems unlikely.

The 11 kW rating on the placard (at 48 V, and a fixed and unknown speed) is for 15 minutes, not 15 seconds.

I would not push that motor's output without a thermocouple monitoring winding temperature.
I agree. The same could be said for any of the "forklift" projects.
 

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Power is power, and power is what's needed to balance rolling resistance and a box pushing air at speed.

Sustained 11kW on a highway is smoke pouring out, no matter how you slice voltage & current. Unless you actively cool the windings.
 

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Power is power, and power is what's needed to balance rolling resistance and a box pushing air at speed.

Sustained 11kW on a highway is smoke pouring out, no matter how you slice voltage & current. Unless you actively cool the windings.
Power is the same no matter the combination of voltage and current, but the limitation of the motor isn't power at all - it's the heat generated internally and the ability of the motor to dissipate it. And that certainly does depend on current and on rotational speed.

But if the point is to convince theonetruerat that an antiquated motor intended for 48 V operation is not suitable for a modern vehicle, I'll agree with that. ;) On the same basis, the entire NetGain product line - other than the HyPer 9 (which they don't manufacture) is also unsuitable. None can sustain significantly more power than the random motor discussed in this thread.
 

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Discussion Starter · #10 ·
Sorry, I guess I stuck a picture of the wrong motor badge - it's 9 KW at 1 hour. It's going in a mid 80s Toyota that is super light (most of the truck is gone) the truck hasn't gone over 25 MPH for years - hasn't been out of low range for years. It, won't be going more than 10 miles at a stretch either.

The motor is about 11" diameter and about 16" long.


I'm mostly interested in sussing out the cooling fan. I was hoping someone had dealt with a similar motor before and could give me the skinny. I'll put a volt meter on it when I get back to my shop and spin it with an air gun. See what that tells me.

thanks to everyone who took the time so far.
 

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I'm mostly interested in sussing out the cooling fan. I was hoping someone had dealt with a similar motor before and could give me the skinny. I'll put a volt meter on it when I get back to my shop and spin it with an air gun. See what that tells me.
Also from your pics it's not visible - are the wires color-coded, or are they all the same color ?
 

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So, I haven't posted In a while because my electric boat project stalled and I have been working like a mule but .. . .

The motor recently blew on my farm truck and since I already had a drive motor taking up space I've decided to do a conversion. I'll post the build in a different forum.

This is the motor I'm using, It's a bit on the big side but I already have it and it's light compared to the cast iron engine I pulled out - and It will fit.the space just fine.

This motor has a cooling fan which has it's own drive. I'm wondering if anyone is familiar with this and could give me any pointers on how it's powered. It has a three prong plug and I'm unclear how it should be hooked up. Not sure if one is neutral and the other two are low/high I'm planning on spinning the fan and poking the plug with a volt meter to see what that shows but I'd love a little guidance.

also there is what appears to be a signal wire on the other end of the motor if anyone has a clue what that is for.
Excellent - That is a Hitachi motor - its rated to run continuously at 10 Kw - 48 volts and 200 amps

I'm feeding a very similar motor with 1200 amps and 340 volts - but in a much lighter vehicle

200 amps will be perfectly safe - and at 1400 rpm will give you your 10 kW

At 2800 rpm it will give you 20 kW -

and at that higher rpm you will get more cooling so you can go to 400 amps - which gives you 40 Kw

at about 4000 rpm and 500 amps you will get about 75 kW - comfortably and safely

You need to feed that motor with a 150 volts and 500 amps - 75 kW - 100 Hp

HOWEVER that is with a motor like mine that has a cooling fan on the motor shaft!!!!

That motor has some sort of fan at the drive end - it can be an electric fan - or it may be some sort of geared fan to get more cooling at low speeds
 

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Power is power, and power is what's needed to balance rolling resistance and a box pushing air at speed.

Sustained 11kW on a highway is smoke pouring out, no matter how you slice voltage & current.
Umm... like, 10 years worth of the entire DIY EV community's projects using motors this size for this purpose says otherwise. Seriously, this was the build for a solid decade here. You can check the biggest thread on the site here about forklift motor repurposing for EV use, it's gotta be hundreds of pages long by now. Commercial EV shops built these, professionally, for tens of thousands of dollars, for a decade. It's very well demonstrated to be just fine.

A few reasons your statements are wrong:

1 - A power rating is just that, a rating. It's an engineer's (or marketing) guarantee for a particular application. A rating might also be quite conservative, or quite generous, depending on the situation. A rating is not a limit. As with anything, context is king. A forklift motor with no air cooling, covered in mud, sitting in the desert sun, scalding hot all day, put through that use, would still hold up.

2 - The context of a rating as a ceiling, is mostly to do with the current in the coils. The wires are only so thick, and they'll have a certain amount of resistance, so they'll build up a certain amount of heat with a given amount of current flowing. Power, as you stated, is power, and is agnostic as to its source. A certain amount of power is needed for rolling resistance and air pushing. However, a wire melting is not agnostic. 11kw @ 48v = 230 amps. But 11kw @ 144 volts = 76 amps. 1/3 the current, and running far cooler. Or, more likely, you maintain 230 amps as your near-continuous ceiling, and give it as much voltage as you feel like, up to a reasonable limit. Eventually, voltage limits will come into play, but that's largely to do with the thickness of the enamel on the wires, which is usually an order of magnitude or more overbuilt.

3 - Extra context... a forklift motor is rated for that load with effectively zero (probably if dirty), or at best just passive air cooling. A forklift motor travelling at highway speed is akin to one in front of a fan blowing 60mph air at it. It's a massive amount of air cooling. A fan or scoop would help even more.
 

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Sorry, I guess I stuck a picture of the wrong motor badge - it's 9 KW at 1 hour.
Thanks for the correction - it wouldn't materially change any of my comments.

It's going in a mid 80s Toyota that is super light (most of the truck is gone) the truck hasn't gone over 25 MPH for years - hasn't been out of low range for years. It, won't be going more than 10 miles at a stretch either.
That's reasonable. :)

You might consider removing the original transmission and coupling the motor directly to the input of the transfer case, using the low range of the transfer case to get a suitable motor speed.

The motor is about 11" diameter and about 16" long.
That's actually larger in diameter than the basic 9" "forklift" motor used in car conversions, and probably suitable for the truck.

I'm mostly interested in sussing out the cooling fan. I was hoping someone had dealt with a similar motor before and could give me the skinny.
Sorry, I can't help there!
 

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Discussion Starter · #18 ·
Cool, so I'd try applying 12v to Red (pos) and Black (neg) momentarily and see if that gets the fan going. If it refuses to spin at once, don't leave the power connected :) There is also a chance it's intended for 24v, but I think 12v should get at least some kind of action.
Well .. . . I tried spinning the motor and checking the leads for voltage. Nada.

Then - I took it to the fork DC motor repair guy who has worked on his share of fork lift motors and he said he'd never seen one with the cooling fan independently powered. He also suggested poking it with power (and a fuse) I tried that and some combinations will make the fan stop rotating if I had it spinning but none will make it spin. I even tried with the main motor energized.

I think I'm going to have to have to open this behemoth up and see if I can suss it out in there. I was really hoping to not have to take the front off. IT's heavy and awkward and I just know I'll be missing the tip of at least one finger before I'm done.

I figure If I can't figure out how to make it spin I can always Pin it to the shaft some how so It spins with the rest of the motor.
 

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Well .. . . I tried spinning the motor and checking the leads for voltage. Nada.

Then - I took it to the fork DC motor repair guy who has worked on his share of fork lift motors and he said he'd never seen one with the cooling fan independently powered. He also suggested poking it with power (and a fuse) I tried that and some combinations will make the fan stop rotating if I had it spinning but none will make it spin. I even tried with the main motor energized.

I think I'm going to have to have to open this behemoth up and see if I can suss it out in there. I was really hoping to not have to take the front off. IT's heavy and awkward and I just know I'll be missing the tip of at least one finger before I'm done.

I figure If I can't figure out how to make it spin I can always Pin it to the shaft some how so It spins with the rest of the motor.
Speaking of pinning the fan to the motor shaft.... perhaps the wires are to control a clutch, connecting the fan mechanically to the motor shaft only when needed for cooling. That would be visually apparent if you could see the end of the motor shaft and whatever device (motor? clutch?) is on the fan.
 
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