# How much torque



## Salty9 (Jul 13, 2009)

9.9 kw = 13.27 hp


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## Tesseract (Sep 27, 2008)

And more specifically, Torque (in lb-ft) = (5252 x Hp) / RPM

Your motor is rated for 9.9kW (13.27hp) at 1000 RPM so the torque will be 69.7 lb-ft. 

Additionally, torque is approximately proportional to the square of current at low currents (ie - doubling current quadruples torque), but it changes over to being linearly proportional at high currents. So, doubling the current will get you somewhere between 2x and 4x the torque (all other things being equal).

This motor, btw, sounds a bit small for a car. Is it a pump motor?


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## Yabert (Feb 7, 2010)

Tesseract said:


> This motor, btw, sounds a bit small for a car.


Why a bit small?

13 hp at only 1000 rpm is powerfull!
And 265 A for 1h is a lot!!

Probably around 40 hp for 1h at 144v!


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## Yabert (Feb 7, 2010)

Similar motor????.5BT1......... : http://www.evalbum.com/921

If the answer is yes, this motor can give you over 100 hp with proper battery and controller!


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## execelon7 (Jan 25, 2008)

Tesseract said:


> And more specifically, Torque (in lb-ft) = (5252 x Hp) / RPM
> 
> Your motor is rated for 9.9kW (13.27hp) at 1000 RPM so the torque will be 69.7 lb-ft.
> 
> ...


Thanks for the info, I will be using it in either a S10 or a Ranger. 
The motor came from a Nissan forklift.
thanks.


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## Georgia Tech (Dec 5, 2008)

Tesseract said:


> And more specifically, Torque (in lb-ft) = (5252 x Hp) / RPM
> 
> Your motor is rated for 9.9kW (13.27hp) at 1000 RPM so the torque will be 69.7 lb-ft.
> 
> Additionally, torque is approximately proportional to the square of current at low currents (ie - doubling current quadruples torque), but it changes over to being linearly proportional at high currents. So, doubling the current will get you somewhere between 2x and 4x the torque (all other things being equal).


Major when you say the Torque goes up linearly with the current at high levels...doen't the torque level out some where due to saturation?


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## major (Apr 4, 2008)

Georgia Tech said:


> Major when you say the Torque goes up linearly with the current at high levels...doen't the torque level out some where due to saturation?


That was a post by Tess. But to answer your question.........Saturation means little if any additional flux can be had in the magnetic circuit. Torque is the product of armature current and flux. So even if flux is maxed out, torque will still increase proportional to increase in armature current.

This stays pretty true for series wound motors, however for shunt and PM, the armature current actually causes net flux to decrease due to armature reaction so the proportionality of increasing torque to armature current isn't so clear.

Regards,

major


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## Yabert (Feb 7, 2010)

execelon7 said:


> Thanks for the info, I will be using it in either a S10 or a Ranger.


http://www.diyelectriccar.com/garage/cars/260
Pick-up with 9" GE motor.


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## JRoque (Mar 9, 2010)

major said:


> Saturation means little if any additional flux can be had in the magnetic circuit. Torque is the product of armature current and flux. So even if flux is maxed out, torque will still increase proportional to increase in armature current.
> 
> This stays pretty true for series wound motors, however for shunt and PM, the armature current actually causes net flux to decrease due to armature reaction so the proportionality of increasing torque to armature current isn't so clear.


After reading that, I'm going to take 2 aspirin and lay down for a while. I ask that you please refrain from using such big words on a forum accessible to small minded people like myself. You hurt me man, you hurt me.

JR


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## major (Apr 4, 2008)

JRoque said:


> After reading that, I'm going to take 2 aspirin and lay down for a while. I ask that you please refrain from using such big words on a forum accessible to small minded people like myself. You hurt me man, you hurt me.
> 
> JR


Should of just said no


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## wb9hco (Nov 11, 2009)

HI All.

I'm still trying to wrap myself around sepex motors...
In a series wound motor the armature and field current are by necessity the same, while in a sepex they are not so closely related, although there must be some interaction between the armature and the field. 

Would I be correct in assuming that the field current is tailored by the controller to present the same flux density as a series design at max torque by virtue of more turns of smaller wire? ie higher voltage on the field than a series motor and more turns to yield the same flux density?
What controls the maximum RPM? A series motor will speed to destruction with sufficient input KW and no load. 

From what I read a sepex motor can run at higher than nameplate rpm (mine is rated at 25 HP 96.8 V 224A 2350 RPM) but how much higher?

If it means higher voltages, are they more or less linear?. I need about 3600 RPM for my donor car to be practical. For my motor that would be about 148 volts.

I think that this motor is large enough that I can get away without the transmission. Total weight without the IC engine and EV components will be about 1400 pounds, a Triumph Spitfire.
If nothing else I'll have a cool NEV if I can't get the RPM up enough...

Paul


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## major (Apr 4, 2008)

Hi Paul,

Some comments inserted.......



wb9hco said:


> I'm still trying to wrap myself around sepex motors...
> In a series wound motor the armature and field current are by necessity the same, while in a sepex they are not so closely related, although there must be some interaction between the armature and the field.
> 
> Would I be correct in assuming that the field current is tailored by the controller to present the same flux density as a series design at max torque by virtue of more turns of smaller wire? ie higher voltage on the field than a series motor and more turns to yield the same flux density?


This is pretty much correct 



> What controls the maximum RPM? A series motor will speed to destruction with sufficient input KW and no load.


A minimum flux level, at minimum. Since the field current is decoupled from the armature current, the controller can maintain field current level to provide sufficient flux at very low loads to keep motor speed reasonable. 



> From what I read a sepex motor can run at higher than nameplate rpm (mine is rated at 25 HP 96.8 V 224A 2350 RPM) but how much higher?


I am sure it can. But be careful of commutation difficulty at high voltage. I can't say, just beware there are limits.



> If it means higher voltages, are they more or less linear?. I need about 3600 RPM for my donor car to be practical. For my motor that would be about 148 volts.


Yes, if you keep the load and field the same as before. But realize that with a SepEx system, you can achieve higher RPM at the same voltage via field weakening. This method is unlikely to increase power, meaning you'd see the higher RPM needing less load. This is difficult to predict exactly because here again you're hostage to limits of commutation.

Regards,

major


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## toyolla2 (Jun 21, 2010)

Hey Yabert,
in reply to Excelon7 you suggested 144v on his 43.5v motor.
Please don't. If we are referring to a DC machine then I can assure you that this amount of overvolting will roast this motor by virtue of its iron loss.

Often times if you want a DC motor to run faster then weakening its field is the way to go NOT by increasing its voltage. Gradual field weakening is good because it puts the motor into a constant power condition, i.e. you have max volts and max current at the same time while the motor is continuing to spin faster. This reduces the strain on the battery - no need for abusive short bursts of very high current when getting up to speed.

On overvolting my personal experience with one motor on a dyno arrangement was that no more than a 25% voltage increase is allowable. After that point you will see iron loss going up exponentially even with a no load situation. The english of which is that even when coasting the motor would be applying a significant braking torque.

It wasn't mentioned how many commutator bars exist between brushes. As a rule allow no more than 18 volts per bar. This will avoid a "ring of fire" situation which you might see at 144Vdc with this particular motor.


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## Yabert (Feb 7, 2010)

Why?

Read this: http://www.diyelectriccar.com/forums/showthread.php/using-forklift-motor-and-choosing-good-7598.html

You can see here many GE motor who are running over the rated voltage: http://www.evalbum.com/mtrbr/GENE



> It wasn't mentioned how many commutator bars exist between brushes. As a rule allow no more than 18 volts per bar


That sound good..... example: 49 bar / 4 -2 (each one touching the brush) = 10 x 18v = 180v


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## toyolla2 (Jun 21, 2010)

Er yes Yabert,
but breaking this particular rule is not something to be encouraged unless you are running a 12 second 1/4 mile dragster perhaps.

And I wonder whether the majority of these builders are aware that the elevated temperatures of their motors are mostly due to excessive iron loss ? Probably they believe the motor was just working hard. 

Some drivers have told me that changing into third or even fourth gear immediately after accelerating produces more economy. They attributed this fact to the extra frictional losses when running the motor at high speed, which was therefore to be avoided whenever possible !

However you will get this iron loss effect for both series and sepex motors any time you force the the rotational speed of the motor along with the magnetic flux in the machine to produce a back emf voltage for which the armature was not designed. 

So why do AC motors not suffer from this ? Well if you rewind a 50/60 Hz motor for lower voltage i.e 0.7V/Hz down from 8.0V/Hz and then speed them to 10k rpm then actually they suffer as well. Their iron laminations are too thick for 300Hz. It is not all bad since a vector controlled inverter will lower the applied voltage when the vehicle attains cruising speed and the current drops below the current limit. The reduced flux level that then follows will immediately squelch the excessive iron loss.

The advantage of high rpms is you get to use the same iron and copper many more times per second than most conventional DC machines are accustomed which translates into a lighter and cheaper motor for the same power.

Did I say " than most conventional DC machines" ? - what about those DC machines that are speed capable. The first EV drive I worked on, way back, used a decommissioned ASG which was 10k rpm capable. These 400 amp SEPEX were built for 28Vdc aircraft duty and will take as much as a 36Vdc overvolt, but that is about the limit for efficient running. The huge rpm range allowed the selection of 1st gear to 44mph or an early selection to 2nd to avoid a clutch operation on the way to achieving even faster speeds. The new problem became that conventional manual autos will not accept 10k input. Approaching 7800 rpm, in our case, proved problematic.

Does the "If you can do it then it's not bragging" rule apply on this board ?

If so I will add that we were able to control this motor with an MC34060p pwm chip feeding into a TIP147 10 Amp pnp darlington transistor that drove the shunt field to 9amps max. Both field and armature current feedback were fed to this amplifier and we were able to control +/- 400 Amps. 
The armature cct would cut in as the motor exceeded its base speed of 2800rpm. At this point the armature would be directly connected across the battery with no 400 amp power transistors involved so Zilla eat your heart out ! 
We could have gone to 1000Amps and 88lbs-ft ( to do so is basically choosing the correct 1/4watt resistor in the feedback circuit) or even higher had we wanted but preserving the life of the two parallel strings of 6 volt golf cart batteries and avoiding a wiring upgrade took that off the table. For those interested in concepts, think of this technique of field control as basically using the motor as a rotating amplifier. Similar to a series motor, some would argue, which explains their adoption in street cars from about the 1870's. 

The shunt field version, I came up with, partly replaces a full time armature controller, though you still need one for the initial launch. It also offers regen in spades as a byproduct. 

But much more importantly it provides a rectangular power profile which series motors do not. A *shunt* motor builds to maximum power and continues to deliver beyond that point. Since a *series* motor can only accelerate by weakening its field this means its armature current must reduce ! Therefore its power profile is triangular. Its power will be seen to drop off after passing through the max power point. Clearly that is not the case with my circuit. I know that only a few out there will be able to comprehend this.
Simply put, for those that have trouble conceptualizing triangles and rectangles graphically, try this. The diagonal across a rectangle divides it into two triangles. If the enclosed area represents the power delivered over the acceleration cycle, is it not clear that the triangular case delivers only HALF the power of the rectangular case EVEN THOUGH both methods play with exactly the same bus voltage and peak current ? OK, perhaps not. Let's move on.

These days I don't play with ASGs, my ASG was sold for use in a concrete cutting application where they wanted a portable machine to run off of the 24 volts supplied from their truck.

I believe that *High* revs together with *Low* voltage continues to be a good strategy to adopt, although not as low as the 36V that I was obliged to use. I would have liked to have tried my system on 96V but finding suitable candidate motors at an affordable price prior to the arrival of the internet would have been practically impossible. Today I am looking at an AC motor which at under 20lbs I'm hoping is going to survive a 30 sec rating of 27Hp and 35lbs-ft.

The thrust of this post has been to advise against over-volting the nameplate voltage on a DC machine by more than 25%. 
That the employment of a field weakening scheme relying on armature current feedback to control the shunt field of a SEPEX motor is a better way to boost the RPM range of a DC machine.
And that this is a more preferable solution than using a series motor.


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## execelon7 (Jan 25, 2008)

toyolla2 said:


> Er yes Yabert,
> but breaking this particular rule is not something to be encouraged unless you are running a 12 second 1/4 mile dragster perhaps.
> 
> And I wonder whether the majority of these builders are aware that the elevated temperatures of their motors are mostly due to excessive iron loss ? Probably they believe the motor was just working hard.
> ...


Hello toyolla2 , thank you for your input, it was very informative ( most of it Way beyond my comprehension ) . This is my first attempt at a EV and my knowledge is very limited. My mechanical skills are about average, I did a engine conversion of a Mazda Rx7 . I replaced the Rotary engine and transmission with a chevrolet 4.3l and a 700r4 auto trans. I would like to begin as soon as possible but it is in instances such as this I am glad I havent proceeded yet.I do understand There is no Free Lunch. To obtain more power/torgue from a ICE you have to modify it by either increasing the cubic inch or the Fuel delivery . The preformance you get is quite noticabe but not without sacrifice. More power=more heat=decrease in Longevity, not to mention the RPM factors. My assumption this also applies with the electric motors. My intial plan was to use eight six volt batteries for power . As you stated a 25% increase in voltage is max, so therefore I will not exceed the limits. Could you please explain 
" Gradual field weakening is good because it puts the motor into a constant power condition " ? If I do this what preformance will I loose ? Just my guess it would be torque. Anyway, this is my plan so far I have a (see name plate info )
GE MOTORS
PART NO.2901-8G200 AU1840 
DC VOLTS 43.5 SER NO. XX-XXXXX-XX
KW 9.9 RPM 1000 ENCL OFC
DUTY 60 MIN CLASS H AMPS 265
MODEL NO. 5BT1366B158B 11" dia 16.5" long









SPEED CONTROLLER
TYPE SCE3-N42
MFG.NO 9Y037 (ISO)
Hitachi,Ltd. Tokyo Japan









These came from a Nissan forklift model CWP02L25S , with a GE dc 9.9 kw 43.5 volts 1000 rpm motor GE part number 29010-8G200
NISSAN CWP02L25S

















I have still yet to acquire my donor vehicle. I want to use either a Chevy S10 or a Ford Ranger. My requirements are a 20 mile range and a top speed of 45mph,is this doable with what I have so far. Thank you so much , Roger.


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## EVfun (Mar 14, 2010)

It looks like a suitable motor Roger. GE motors have a good reputation and an 11 inch diameter by 16 inch long motor should be plenty large (and heavy.) You want a motor that weighs around 150 pounds for a small pickup. You will have to figure out how to attach to the splined output shaft.

Commutator bar count and wiring would be the next things to look at. If you remove the bigger vent you can get a look at brush size and comm bar condition and count. You can determine a reasonably expected max motor voltage by counting the open slots that are between 2 comm bars. Count the slots between 2 adjacent brushes and multiply by 20 for an estimate of the voltage the motor can take. If you see 4 large posts to connect wires to on the outside of the motor then it most likely series wound. If 2 of the posts are small then it is most likely shunt or sep-ex. Those kind of motors can be used, but series wound motors are most common for DIY conversions. 

I doubt the controller will be of much use to you. I don't recognize it but most forklift controller are very low voltage for on-road EVs. If you really only expect 45 mph top speeds it may be possible to use it.

There was another thread here on a GE motor with similar numbers on the name plate. Here is an ended ebay auction on the exact same motor.


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## Duncan (Dec 8, 2008)

Hi Guys
_*The thrust of this post has been to advise against over-volting the nameplate voltage on a DC machine by more than 25%. 
That the employment of a field weakening scheme relying on armature current feedback to control the shunt field of a SEPEX motor is a better way to boost the RPM range of a DC machine.
And that this is a more preferable solution than using a series motor.*_

There are some problems with this statement

(1) There are very few controllers for SEPEX motors

(2) Most importantly - 
Your controller operates by effectively reducing the battery voltage to the voltage required by your motor at that specific speed and load - the motor does not see battery voltage until the controller is at 100% - drag strip time! - only a very powerful controller will let you go there 

(3) Iron losses?? - the statement appears to be that higher RPM's cause iron losses because the laminations are too thick,

6000rpm = 100Hz or 400Hz with four poles

I am a mechanical engineer but I would have thought QER and Tesseract would have understood this and not run their very successful controllers at 20,000Hz
(I want a Soliton but I've got an OpenRevolt for financial reasons)
Maybe its not important?

I recommend ignoring Toyolla2 and continuing with as high a voltage as your controller can handle.

Can one of the actual experts like Major or Qer, either confirm or tell me I'm full of it?


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## Tesseract (Sep 27, 2008)

Duncan said:


> I recommend ignoring Toyolla2 and continuing with as high a voltage as your controller can handle.
> 
> Can one of the actual experts like Major or Qer, either confirm or tell me I'm full of it?


Well, I didn't get included in your list of experts - which was accurate of you  - but you probably should have left Qer out, too... 

You are correct - iron losses from commutation are pretty much irrelevant in a DC machine. The armature (rotor) in a DC machine does see alternating magnetic fields from commutation, but the field (stator) does not.

The PWM frequency used by the controller does create iron losses of relevance, however, and this is another argument to not use a higher switching frequency than what is necessary to minimize whine. Iron loss is approximately proportional to the 1.6 power of frequency, btw (the proportion is not exact integer because several different losses go into "iron loss").


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## execelon7 (Jan 25, 2008)

EVfun said:


> It looks like a suitable motor Roger. GE motors have a good reputation and an 11 inch diameter by 16 inch long motor should be plenty large (and heavy.) You want a motor that weighs around 150 pounds for a small pickup. You will have to figure out how to attach to the splined output shaft.
> 
> Commutator bar count and wiring would be the next things to look at. If you remove the bigger vent you can get a look at brush size and comm bar condition and count. You can determine a reasonably expected max motor voltage by counting the open slots that are between 2 comm bars. Count the slots between 2 adjacent brushes and multiply by 20 for an estimate of the voltage the motor can take. If you see 4 large posts to connect wires to on the outside of the motor then it most likely series wound. If 2 of the posts are small then it is most likely shunt or sep-ex. Those kind of motors can be used, but series wound motors are most common for DIY conversions.
> 
> ...



Here are some more pics. My main concern is the Max sustainable RPM this motor will handle with out any damage. My plan (so far ) is to use the controller that came from the forklift, I have all the wiring harnesses and gauges and controls and a wiring diagram also. But That is another concern for a later time. I plan on using 7 , 6volt golf cart batteries. The motor states 43.5 volts and Im sure the controller is designed for that and I would be afraid to exceed the voltage. Perhaps you can tell something from the schematic pic. My requirements are 45 MPH 20 MI range . The motor says 1000rpm , but I dont know if the controller has any type of limiter for the motor rpm or the speed of the forklift was determined by the gear ratios of the transmission . From all the info I have gathered from here so far is a manual transmission no clutch works well. But, I finally found a great deal on a donor veh (if he doesn't back out) and it has a autotrans. This is where the problem is if I cant exceed 1000k rpm. The autotrans has to normally reach 1000-2000k RPM to shift. I know there also other determining factors for the shift pattern,throttle control linkage and overdrive lock up and the ECM. So a long question short, what is the MAX RPM I can use this motor at without damage ? Thanks again to all who have assisted me, Roger. UPDATE, I saw on the schematic that I can use 48 volts .







Motor terminals







Rear of motor







schematic


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## major (Apr 4, 2008)

execelon7 said:


> The motor says 1000rpm ...... So a long question short, what is the MAX RPM I can use this motor at without damage ?


Hi ex,

1000 RPM is the speed at rated load. Even in the forklift, it ran faster than that. I'd say you could do at least 4000 RPM.

As far as operational voltage for that motor, you could likely go up to 120 or 144. 

It is a series wound motor, so you need to either assure load or sense RPM to cut applied voltage if overspeed is detected. That forklift controller looks like a nice one, but is designed for 48 volts and likely could not be used at higher voltage. You could start with it, but typically 48V is too low for EVcars due to the high current loading of the battery. If you want highway capability, I'd think at least 96V.

Regards,

major


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## execelon7 (Jan 25, 2008)

Thank you Major for your reply.

"but typically 48V is too low for EVcars due to the high current loading of the battery." Major , I am sorry I dont understand what this means. If you can DUMB IT DOWN for me please. This is what I would like to do and here is what I need for it to do. I need it to have a range of 20 miles, charge overnight ,top speed 45 mph. This would not be used on major highways only back roads . 4000 rpm will be great for me, even if I use a autotrans . I need to find out all the info on how to set it up for the autotrans. I dont know anything about amp useage, but from what I understand about the forklift is that it would run 6-8 hours on the charged battery pack . Im sure most of the time was not in a forward motion of the forklift but in using the lift . Here are the specs on the forklift 







I dont know how to calculate the weight speed distance to achieve my needs . Thanks again ,Roger


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## execelon7 (Jan 25, 2008)

Oh, who has or is using a automatic transmission that could give me some info on how to do it ?


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## piotrsko (Dec 9, 2007)

execelon7 said:


> Oh, who has or is using a automatic transmission that could give me some info on how to do it ?


1:read the threads on auto trannies in the technical forum

2:buy an adapter kit and use the flex plate instead of a flywheel ( requires idle circuit in controller)

3:get the adapters from say TCI to convert the trans over to circle track which generally doesn't use a torque converter ( requires appropriate trans, usually rwd)

4:talk to the auto trans vendor guys over in "classifieds"

good luck, have fun !!!


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## EVfun (Mar 14, 2010)

48 volts ends up being to low because the current ends up so high. With cars it is traditional to think about horsepower. If you multiply the pack voltage times the current coming out of that pack, and divide by 1000 to converts watts into kilowatts, you can get a rough estimate of horsepower (gross simplification.)

So with a 48 volt pack at 500 amps you only have about 24 horsepower peak. Golf cart batteries tend to complain terribly above that current level. 120 volt at 500 amps is about 60 horsepower and a lot more drivable. Traditional golf cart battery powered EVs are never fast, but 60 pounds of car for every horsepower puts you in the performance category of a 36 horsepower Beetle ('50's Beetle.)


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## execelon7 (Jan 25, 2008)

If I do use the 48volt system with my motor and a manual transmission what type of range /performance can I expect ? Donor veh 1989 GMC S15
If it will give the same or close to the same performance as a golf cart, it will suit my needs.

















GE MOTORS
PART NO.2901-8G200 AU1840 
DC VOLTS 43.5 SER NO. XX-XXXXX-XX
KW 9.9 RPM 1000 ENCL OFC
DUTY 60 MIN CLASS H AMPS 265
MODEL NO. 5BT1366B158B
With this speed controller
This is the Nameplate from the forklift it shows the weight 








This is the wiring diagram ,








I noticed it has 12v outputs for the headlamps accs ect , I am hoping I can also use this to power the cars 12v system. So what do you think ? Thanks again, Roger.


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## Yabert (Feb 7, 2010)

execelon7 said:


> If I do use the 48volt system with my motor and a manual transmission what type of range /performance can I expect ? Donor veh 1989 GMC S15
> If it will give the same or close to the same performance as a golf cart, it will suit my needs.


265A at 48v give 13-14 hp at output shaft of the motor.
This is only true if the controller can sustain 265A continous (or 1h) and if your battery will be really strong (don't sag under load).

13-14 hp is probably enought to maintain 30 mph with a light pick-up.

About acceleration, they will probably be terrific. Barely enought to go with the trafic.

The range depend of the total Kwh you will have in your pick-up. Kwh = batt volt x Amp hours rating of the battery.
Ex: 48v x 200Ah = 9.6 Kwh.

I think you can try like this because your availiable parts are very cheap. And after, when you will take realize of the poor performance of your EV, you will can upgrade your set up with a new controller and more battery (more voltage) but stay with the same motor.
Probably 500 to1000$ for a cheap controller.
More voltage (72v, 96v or 120v) will give you more top speed with the same motor.


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## execelon7 (Jan 25, 2008)

Thank you for your reply Yabert, I have checked the RPM and speed factor of the manual transmission at 2000 RPM =55 mph in top gear , the auto transmission is better in top gear with lock up. Please correct me if I am wrong but my understanding of the components comparing to the ICE. Total Volts= fuel tank capacity , amps used= amount of gas used to achieve speed depending on load,terrain acceleration. What I need to know is what is the SWEET SPOT for the torque/rpm range . In other words is where the torque is still on a level plane compared to the rpms, I have seen some graphs here, wish I could find them, where the motors torque did not drop off until 1800 rpms . I have found this info on using a autotrans. http://civicity.blogspot.com/2009/10/how-i-used-automatic-transmission-in-ev.html . I also found a lot more info here on how to adjust the shift pattern on the autotrans . This would be a ideal set up for what I need , for the transmission to shift at 1800 rpm and to use lock up in top gear.


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