# New EV Calculator



## ZX-E (Aug 31, 2009)

Hi all,

I recently wrote a program that should help determine the ideal gear ratio and other characteristics for electric vehicle conversions. All you need are a few parameters for the vehicle and a torque vs rpm plot. If you can't find a torque curve for your particular motor, estimating the it is actually pretty simple. The program will output the 0 to 60 time, top speed and quarter mile. The program obviously isn’t perfect and it has its limitations, but it does what it is designed to do: find out how fast you're going to go, and give you an idea of what you might want to improve. I’d love to hear what you guys think about it. 

UPDATE Sept 30 2009: The program can simulate a shift to another gear ratio at a certain RPM
UPDATE Feb 23 2011: The program can now calculate 0 to any speed, instead of just 0-60 times
UPDATE Feb 26 2011: Downloadable 64 bit version! http://www.hvbikes.com/downloads.htm

What inspired me to make the program was a thread on an AC-55 conversion where people were throwing around gear ratios with from what I could tell, little reliable simulation comparison. I tried out a few gear ratios out myself using the program and the information on AzureDynamic's torque vs rpm curve, and came up with a faster zero-sixty time using a 4 to 1 ratio instead of a 6 to 1 ratio like the before mentioned thread seemed to agree on. The steep torque drop off at 2000 RPM really has a significant impact on acceleration at higher speeds. The higher RPMs from the 6 to 1 gear ratio at cruising speeds are however easier on the motor, but that's beside the point.


Here are some screen shots from the program using specifications for a Tesla Roadster:



































Left click to add data points, right click to delete them:







































-Rich


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## major (Apr 4, 2008)

ZX-E said:


> After reading quite a few posts where people are guessing what gear ratio they would need for single speed conversions, I came up with a MATLAB program that should help out. -Rich


Hi Rich,

Looks like you might have something there 

Any chance you might want to help us out on another thread? Look at http://www.diyelectriccar.com/forums/showthread.php/torque-irrelevant-relevanti-36904p3.html post #23.

I would appreciate it.

major


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## major (Apr 4, 2008)

major said:


> Any chance you might want to help us out on another thread? Look at http://www.diyelectriccar.com/forums/showthread.php/torque-irrelevant-relevanti-36904p3.html post #23.


I just want to compliment Rich (ZX-E) on the most excellent job he did with this program and the simulation which he was kind enough to run for me. http://www.diyelectriccar.com/forums/showthread.php/torque-irrelevant-relevanti-36904p3.html post #25.

I think what he has here is a great tool. And I hope he is kind enough to somehow share it with the community. 

Nicely done, Rich 

major


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## ZX-E (Aug 31, 2009)

Thanks Major,


There might be some issues compiling it to a .exe file. There is a possibility I'll be able to work something out in the next few weeks though.

Hopefully I'll be able to put in an option to shift gears as well. What do you think? A two speed transmission should be pretty easy to implement. I'll have to fit it in between classes .

Could someone post the specs for their car so I can test it out? Anyone using an AC55?


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## major (Apr 4, 2008)

ZX-E said:


> What do you think?


I think it's great. Pretty much all my EVs have weird motors or no good tested performance to help you out  I appreciated your help with Drew. Can't understand his point of view. But everybody's entitled to an opinion.

While we're on it, I got a problem with my computer, or the operator  I cannot seem to include in my post a paste of things like an excel chart, or even a word file. Like for the example you ran for me, I plotted the two specs from Bowser in Hp vs PRM plot in excel. No problem. But no way (that I can figure out) to post the plot in a response to him. I see other guys (and you) apparently just paste in stuff. How do you do that?

Just a computer dummy here 

And if a computer dummy can help you getting this tool out there, don't hesitate to ask.

Thanks again,

major


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## ZX-E (Aug 31, 2009)

I just got it to do two speed shifting. Woo Woo. 

Anyway yea you have to upload your pictures to photobucket first. Then when you make a post here click the "Insert Image" icon and you can enter in the url of the photobucket image.


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## Batterypoweredtoad (Feb 5, 2008)

ZX-E, Major, Can you guys help simulate this one?

I hope to eventually convert a 1992 Lexus SC400 to an electric drag car on the cheap. There are better choices, but this is just a fun calculation for now.

I will be using a 350lb GE *5BT1378B6* 13" Motor.
The nameplate gives 140ft/lbs of torque at 925 rpm, 48 volts, and 467 amps. I hope to use 14, 12V optima yellow tops to get around 140 volts and 900Amp capability for the length of a 1/4 mile run. I think I will limit the motor to 4000 rpm. I dont have good information on torque at other rpm, and amp ranges. The best I have is a 72V graph for a Warp13. Major-can you help estimate what would happen at double nameplate amps and triple nameplate volts? Here is the Graph for the WarP motor:










Wow that is a big graph, sorry!


For this exercise lets assume I have a controller that can survive this.

The transmission is a powerglide with a first gear that can be either 1.76/1, 1.82/1, or 2.0/1, and a second gear of 1/1. Lets assume 1.82 for this exercise.

The final drive is either 3.62 or 3.29. Lets use 3.62.

The tire size is 225/55/16.

The coefficeint of drag is .31

The weight will be approximately 3800lbs.

I guess we assume perfect traction as well?

Thanks guys,
Josh


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## ZX-E (Aug 31, 2009)

Here Josh. I set up the car with your specifications. I estimated a peak torque of 300 [ft-lbs]. I had the torque start dropping off at 2900 RPM and hit 180 [ft-lbs] at 5000 RPM. I hope you're ok with an educated guess for the motor output. Major can probably come up with something better later.










Check out the new transmission input!













































Not exactly a drag racer, but it's a damn fast commuter.

-Rich


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## Batterypoweredtoad (Feb 5, 2008)

Thanks for the calcs!

Sounds like I need more volts and amps, and less weight! (and more rear gear)


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## frodus (Apr 12, 2008)

I think you need a little more cowbell


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## ftaffy (Mar 13, 2009)

Hey Rich, 

I have an interesting one for you, be interesting to see if my estimates are correct:
Warp 9 - specs: http://www.go-ev.com/images/003_16_WarP_9_SpreadSheet.jpg; http://www.go-ev.com/images/003_15_WarP_9_Graph.jpg
Car: Lotus 7 replica (Locost)
Batteries: 144V 60AH Thundersky (45 batteries)
Open Revolt controller: 144V 500Amp
Weight: 613kg (est total including 2 people)
drag coeff: 0.6 (its a brick)
Frontal area: 1.59m^2
Drivetrain efficiency: 0.9
Direct drive: Ratio: 2.92
Wheel radius: 0.28m

No urgency but would be interested. 

Cheers
Taffy


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## ZX-E (Aug 31, 2009)

What torque were you expecting at 500 amps?


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## ZX-E (Aug 31, 2009)

Nevermind I'll just go with 110 ft-lbs. I found a site with some info. (evparts.com)


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## ZX-E (Aug 31, 2009)

At evparts.com their motor test of the ADC 9 at 120 volts gives 58 hp peak @ 2800 RPM. I had the torque for your motor start dropping off at 3300 RPM because you're using a little higher voltage.

I've been getting a better understanding of how electric motors work, but by no means am I an expert. Any input would be much appreciated.










103 mph top speed
12 second 0-60
19 second quarter mile @ 82.7 mph



I'll post/email you graphs if you want 'em


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## ZX-E (Aug 31, 2009)

Ok, Batterypoweredtoad. 

I was thinking something was fishy with those calculations I did for you. The shifting option wasn't working right because the RPM wasn't being calculated the way it should when the shift point occurs. You should disregard the first estimates other than the top speed.


if RPM > para.ShiftRPM
newRatio = para.ShiftRatio
end

RPM = Vel/60*(5280*newRatio/(para.WheelCircumference/12));

NetForce = GetDriveForce(LineFitCoeff, RPM,para.WheelCircumference, newRatio)...
- RollingDrag - GetAirDrag(Vel, para.FrontalArea, para.AirDragCoef,para.AirDensity);



Oh well. Here are your new calcs. Thanks for giving me a reason to add the shifting option . It should be working right now.



















Looking better

-Rich


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## ZX-E (Aug 31, 2009)

Ftaffy,

Here you go.


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## Batterypoweredtoad (Feb 5, 2008)

Wohoo!!!!!


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## ftaffy (Mar 13, 2009)

Thanks for that! 
Your sim got a higher top speed (170kph vs 130kph) but slightly slower acceleration (12sec vs 10 sec). But they are within the margins of rounding that i may have done. Thanks again!

Cheers
Taffy


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## ZX-E (Aug 31, 2009)

Interesting. I tried it in another sim and got a 12.25 second 0-60 and 109 mph top speed. Which makes sense because that one didn't account for the torque drop off. That explains why the top speed was a little higher than mine.

Can you post what values you put in your simulator exactly? What was your max RPM?


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## ZX-E (Aug 31, 2009)

Whoever is the first person to post some specs for a car with real life 0-60 times, quarter mile time and top speed gets the first beta version! I'm going to try and use the University of Washington's compiler on the full version of matlab to create an .exe. I'll most likely post it on the forum for free sometime at the end of the month.


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## ftaffy (Mar 13, 2009)

Sorry about the delay, i will get my calc's up tonight when i get home. Had some rather urgent things up in the last few days that left me with no time outside of work. 

Cheers
Taffy


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## ftaffy (Mar 13, 2009)

As promised, how i was doing my calcs. I cut this out of the spread sheet and added some notes. The complete thing is a mess of extra calcs i have been doing. Also have done some battery price vs range comparison stuff, though there are still some flaws in it.

Anyway Rich here it all is:









I then used the motor specs given by Netgain to produce this table, see notes on the side on how it was uprated to 144V.









And came out with the following by having excel trend out the values, would be better if excel (well mine dosnt, though i have seen it) had an interpolate function.









This is the section that shows speeds, accleration etc, its a serious mess so be warned!









And as a bonus what happens when you calc out battery vs range vs cost.
This first table is everything how it was calc'ed. The lifetime is assuming 850 lead acid cycles and 2000 Lithium ion cycles. I also assumed 80% lead acid power available though from some further reading on here this figure should probably be lower, will change that next time i come around to working on this stuff.









This comparison includes doing 15 4 sec 0-60kph accelerations per pack cycle and the rest crusing at 60kph. I picked 60kph as that is the general speed limit in Aus and it seems like a fair speed.









Anyway i am open to people to telling were i messed up.

edit: The change when you set pbA's to 50% usable power.


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## ZX-E (Aug 31, 2009)

Before I get further into it. Did you mean to have a 2% incline? It looks like that creates more force than your rolling resistance.


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## ftaffy (Mar 13, 2009)

Yes i did, this was help simulate the effect of real world driving that would involve hill climbing. Were i live there are lots of little hills all through the city.


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## ZX-E (Aug 31, 2009)

Ok we're definitely calculating drag the same way. I checked the math and my plots.

The only thing I've noticed that's a little odd is how you're using your rated available power. The motor's power output should be much lower than the peak and increases almost linearly from 0 rpm to the point of peak power. Are you using motor power output correctly?

I did another run with my sim using your 2% incline (essentially doubling the car's weight if your calculations are correct), a 1.2kg/m^3 air density and .018 total rolling drag coefficient. Assuming about about a 83 hp peak again I get a 32 second 0-60, 100mph top speed and a 30 second quarter mile.

You might want to look into how you're using motor power output at different rpms. It seems way too high. Although I could always be misreading how you're doing it.


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## ftaffy (Mar 13, 2009)

Will have a look at it again, but wont get back to it for a few days at least. 
I will look at how i am using motor power and go back to some of my references. 

That 32 seems very high, as other EV lotus 7s in direct drive are said to be very fast off the line. Will see if they have any data on this.


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## ZX-E (Aug 31, 2009)

Well like I said that was using your 2% incline. Which according to your calculations created a hill drag greater than the the rolling drag. If I don't include that incline in my simulator I calculate a 13 second 0-60, 20 Second quarter mile and 101 mph top speed using exactly the same vehicle parameters you used. Which makes sense. (It's a 500 amp system).

If you removed that 2% hill incline your calculations would also be completely different, and you'd have a much faster 0-60.

You should definitely check how you're finding motor power at different rpms/velocities. That's where the problem lies, I'm pretty sure.


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## _GonZo_ (Mar 23, 2009)

About the motor constants usually the manufacturer gives full details on tables it is posible to get the data from there.
If they are not available then it can be estimated that the grateses efficiency of the motor is around 80% of the maximun revolutions it can gets with that given voltage (efficiency will be then around 80 to 90% at that point) so knowing the voltage and amperage at that moment you may know the power of the motor. Just my idea...

You are doing a great job here, Is it posible to download that excell sheet so I can play with it as well.


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## ZX-E (Aug 31, 2009)

ftaffy. For example at 10 mph the motor can only put out 8000 watts at 110 ft-lbs. It looks like you have it doing about 43 kW at all speeds. That would explain why my 0-60 times and quarter mile times are much slower.


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## SolarJ (Sep 12, 2009)

I have a 90 Mazda Miata weight 2300 lbs and am putting a AC55 Motor in it. 4.3 Gear ratio direct drive. 312VDC 60AH. Could you run the numbers?

Thanks, Jim


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## ZX-E (Aug 31, 2009)

SolarJ. I got a 85 MPH top speed, 9 second 0-60 and a 17.3 quarter mile at 72 miles per hour. 

I've been really busy with school so I haven't had much time to work on the program. However, I don't mind running numbers for anyone who asks for them . A 4.3 gear ratio looks pretty good there.


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## SolarJ (Sep 12, 2009)

Thanks for the info! What difference would a 3.9 diff make?
Jim


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## ZX-E (Aug 31, 2009)

At 3.9:1 you'll get a 87 mph top speed, 8.65 0-60, 17.2 quarter mile. 

3.6 is right about the point where you maximize your 0-60 time. 4.3 should be fine though because for the AC 55 I'm pretty sure want to run it at as high of a RPM as possible so you can keep the motor torque down when you're cruising and accelerating.


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## adamj12b (May 4, 2009)

Hey ZX-E, 

I got one I would love for you to run. The car is not done yet, But most of the specs have been calculated already.

Motor: Warp 11 - One hour HP rating = 43 HP @ 72 volts DC 135 Ft. pounds torque - 72 volts, 452.8 amps
Car: 1971 Corvette Coupe
Batteries: 144V 160AH Thundersky (45 batteries)
Modified Open Revolt controller: 144V 1300 Amp
Weight: 2900lbs
Drag coeff: .456
Frontal area: 2,779.2 Sq in
Drivetrain efficiency: 0.9
Gear Ratio 1: 8.4672
Gear Ratio 2: 6.3168
Gear Ratio 3: 4.9056
Gear Ratio 4: 3.360
Max RPM: 5500
Wheel Circumference: 85.2in 

I think thats all the information you need.
The transmission is 4 speed, but 1st is way too low. I will probably race 2-4. Launch in second and skip all the way to 4th for top speed. I plan on racing the car on the strip at 1000A, but If needed I can crank it all the way up. I cant wait to see the result. 

Thanks.

-Adam


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## ZX-E (Aug 31, 2009)

Hey thanks for getting all of those stats for me . 

At first I thought you were going to run it at 72 Volts... Which I thought was a little odd, and my program showed you couldn't even get to 60 miles per hour at that voltage. Then I realized you were running 144V. 

I estimated 270 ft-lbs peak torque and had it start dropping off at about 3000 rpm. I need to find a better way to determine the torque curves at different voltages... But I've been pretty busy with schoolwork.


Here's the torque curve 











And the results


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## ZX-E (Aug 31, 2009)

Oh yea. I had it shift from 2nd to 4th gear at 4000 RPM.



Here are the input parameters I used for your car.


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## esoneson (Sep 1, 2008)

Adam,
I may be really off base, but I think the 1971 Corvette Drag Coefficient is a little lower than you stated. Something on the order of .325 not .456 which would probably change your graph results a bit.

I found 1972 Corvette CdA of 6.27 (in square feet) and at least one Cd of .325 when googling around a bit.

I too would be interested in those graphs since I am looking at a BMW 3 series (.32 Cd) with about the same weight, battery and motor as your 'Vette.

Eric


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## adamj12b (May 4, 2009)

Well, I dont think it would be that low. There is no good results for early C3 Vette's though. 

I would still like to see what the numbers look like for a drag coeff of .325.

I was hoping to numbers a little faster then that. Stock 0-60 is 7.1 and 1/4 mile is 15.5 seconds. I need to be faster then those times....

Anyways. Thanks alot for the numbers already. That program is looking great. I cant wait till you release it, but I know how school is, and thats way more important. 

-Adam


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## SyCo (Feb 15, 2008)

ZX-E said:


> Someone post the specs for their car so I can test it please.


I don't know if my project might be of some interest but just in case . I will be running at 48V and I would like to know what gear is best and what motor rpm (range) I should use ?

Weight 2800lbs

The transmission is manual 5 speed 
1st ; 2nd ; 3rd ; 4th ; 5th
3.615 ; 2.053 ; 1.37 ; 0.971 ; 0.825

Final Gear 3.65

I also have a 1:2 chain drive that constantly double the motor RPM at the flywheel.

Tire size 175/70R13 with a diameter of 22.8"

Frontal area (using dimensions from shop manual) is 2036 inches^2

Max RPM 4000
Max Torque ~185lbs/ft

motor dyno graph (metric)http://i365.photobucket.com/albums/oo96/SyCoQc/EV/ac_motor_img2_2.gif

In case it is needed
*Controller (AC)*:
Curtis AC 1238-5601
36-48V, 650A max (210A 1hr)

*Motor (AC)*:
Prestolite Asia ASDA 4004
15.5Kw, 30.3V, 405A, 1735RPM

Note: all above is from someone new to EV (me ) so please be indulgent if I've posted in the wrong thread.


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## ZX-E (Aug 31, 2009)

What top speed are you planning on with 48 volts?


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## ZX-E (Aug 31, 2009)

adamj. Changing that drag coefficient drops your quarter mile time and 0-60 time by .1 seconds but it increases your top speed by about 10 mph.


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## SyCo (Feb 15, 2008)

ZX-E said:


> What top speed are you planning on with 48 volts?


I was hoping for 40 mph. I know I'm running only 48V but I think I can get more amps to give enough power to reach that speed. Plus I'm using an AC setup and if I was told right it is a bit more efficient than DC.

Then again I'm all new to this and I must read, read, read ! So if I miss something please forgive me .


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## adamj12b (May 4, 2009)

Yea, I didnt think it would make much of a difference. the front area of the car is just huge. lol

Ive read before that the early C3 vette's have the same aerodynamics as a hummer. lol

One more thing, What happens if you change max torque to 425 lb-ft @ 1000A. My friend and I did some math and the Warp 11 based on a quadratic fit should make that. I would be much happier with that amount of power.

I think it will make the times drop like a rock. I would also say that the 2 to 4th gear shift doesnt help, but 3rd will top out around 90 MPH.

-Adam


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## ZX-E (Aug 31, 2009)

Also adamj. I was using 1000 peak motor amps for those calculations. If you do 1300 amps to accelerate you should go faster than the stock corvette.


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## adamj12b (May 4, 2009)

ZX-E said:


> Also adamj. I was using 1000 peak motor amps for those calculations. If you do 1300 amps to accelerate you should go faster than the stock corvette.



OO ok, Well My controller will easily be able to run at 1000A for more then 1 minute. Its the batteries that im worried about.....

-Adam


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## ZX-E (Aug 31, 2009)

How did you come up with 425 ft-lbs? Just curious. I can run it though. If you look at the graph at http://www.evparts.com/img/MT2144Torque.pdf, the torque vs amp plot looks almost linear. If anything you'll have less than 320 ft-lbs at 1000 amps.


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## ZX-E (Aug 31, 2009)

Because you have such a high voltage it will be a while before you're pulling 1000 amps from the batteries. Can you program that controller to limit battery current draw?


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## adamj12b (May 4, 2009)

Hello, 

Its based on the numbers in this chart: 









If you continue the torque line with a quadratic fit, it does slope up. This method only works for series motors. 

If its true, I will be very happy I suspect.

-Adam


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## adamj12b (May 4, 2009)

Yes, I will be able to limit battery current.

-Adam


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## ZX-E (Aug 31, 2009)

SyCo said:


> I don't know if my project might be of some interest but just in case . I will be running at 48V and I would like to know what gear is best and what motor rpm (range) I should use ?
> 
> Weight 2800lbs
> 
> ...


SyCo I need to know two more things about your project. What kind of car are you using so I can find the coefficient of air drag. Also, what exactly is your drive line gear ratio. Are you saying you have essentially a 1.825:1 final drive?

I really like that motor torque curve you have there.


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## ZX-E (Aug 31, 2009)

Hey Adamj. Shifting from first to third at 4000 rpm you get a 6.15 second 0-60. That's still at 1000 amps.


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## SyCo (Feb 15, 2008)

ZX-E said:


> SyCo I need to know two more things about your project. What kind of car are you using so I can find the coefficient of air drag. Also, what exactly is your drive line gear ratio. Are you saying you have essentially a 1.825:1 final drive?
> 
> I really like that motor torque curve you have there.


My car is a 2002 Hyundai Accent 3 door. Some pics of my setup here: http://www.diyelectriccar.com/forums/showthread.php?t=38064



ZX-E said:


> Also, what exactly is your drive line gear ratio. Are you saying you have essentially a 1.825:1 final drive?


hum "drive line" I'm not sure what you mean (sorry I speak french). But look at my pictures in the link above. It's an AC motor mounted to a plate with a 1:2 chain driven multiplication unit. The previous owner did this to limit usage of motor RPM. But I've been told by others that a direct coupling would have been more efficient and if required I could have used the 4th and 5th gear instead of 2nd or 3rd. I can choose any gear from the manual tranny but to answer your question, yes the final drive would equal (3.65/2) or 1.825:1 if I understand this correctly.



ZX-E said:


> I really like that motor torque curve you have there.


Can you give me a bit more details ? Or maybe some advice on how I should "operate" my car to gain efficiency from that torque curve ?! Since I don't want to redo the mechanical part for now, should I limit the motor RPM within the controller and use taller gear or should I try higher RPM with less torque ?!

thank you


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## ZX-E (Aug 31, 2009)

SyCo I think your gearing is quite alright. It's not really worth changing. You're looking at 84 mph top speed in 5th gear. Which is way more than it sounds like you even need. You won't have much torque at that point to do anything anyway. But based on my calculations you _could_ go that fast if you wanted to. 

If your motor is drawing 650 amps you can do 0-60 in 25 seconds shifting from 2nd to 5th at 2000 rpm. Not too bad really. You could drive it on the freeway .


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## SyCo (Feb 15, 2008)

ZX-E said:


> SyCo I think your gearing is quite alright. It's not really worth changing. You're looking at 84 mph top speed in 5th gear. Which is way more than it sounds like you even need. You won't have much torque at that point to do anything anyway. But based on my calculations you _could_ go that fast if you wanted to.
> 
> If your motor is drawing 650 amps you can do 0-60 in 25 seconds shifting from 2nd to 5th at 2000 rpm. Not too bad really. You could drive it on the freeway .


 so you mean IF my motor, which is rated at 405A on the label, was able to draw 650A (and are you talking about AC amps btw? Because I'm still a bit confused with what is coming in _DC amps_ and what is going out to the motor _AC amps_ ) So I would be able to to reach 84mph ?? But how much time would it takes ? 2 minutes ??  Because that is all the time I have since 650A through my controller is for 2 min max according to the specs.

Now, more seriously, do you have my top speed in 2nd and 3rd gear ? Would that be the approriate gears to choose to be efficient and be able to reach 40mph ? What would be the amp draw at that speed according to your calculations ?

Thank you


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## ZX-E (Aug 31, 2009)

AdamJ. Thanks for the insight. You're right about using that quadratic fit with an increasing slope . Here are your new numbers with 425 ft-lbs peak: 0-60 in 4.65 seconds, quarter mile in 13.3 seconds.


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## ZX-E (Aug 31, 2009)

SyCo said:


> so you mean IF my motor, which is rated at 405A on the label, was able to draw 650A (and are you talking about AC amps btw? Because I'm still a bit confused with what is coming in _DC amps_ and what is going out to the motor _AC amps_ ) So I would be able to to reach 84mph ?? But how much time would it takes ? 2 minutes ??  Because that is all the time I have since 650A through my controller is for 2 min max according to the specs.
> 
> Now, more seriously, do you have my top speed in 2nd and 3rd gear ? Would that be the approriate gears to choose to be efficient and be able to reach 40mph ? What would be the amp draw at that speed according to your calculations ?
> 
> Thank you



Yes it would take forever for it to reach 84 mph. And yes those calculations were based on the torque curve you sent me. Which looks like it was about 600 amps peak at the motor. I didn't know your motor was rated at 405 Amps. Is that continuous?

Your top speed in second gear is about 62 mph. 

It sounds like you have a pretty good understanding of your car's limitations SyCo. That's always a good thing to know .


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## SyCo (Feb 15, 2008)

ZX-E said:


> Yes it would take forever for it to reach 84 mph. And yes those calculations were based on the torque curve you sent me. Which looks like it was about 600 amps peak at the motor. I didn't know your motor was rated at 405 Amps. Is that continuous?
> 
> Your top speed in second gear is about 62 mph.
> 
> It sounds like you have a pretty good understanding of your car's limitations SyCo. That's always a good thing to know .


Great! thanks!

The sticker says 405A and below there something about duty saying S2-60min
http://i365.photobucket.com/albums/oo96/SyCoQc/EV/SDC11277800x600.jpg 

not sure if that means continuous amps it can substain during 60 minutes ?!


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## ZX-E (Aug 31, 2009)

Oh yea. SyCo. I didn't just arbitrarily choose 640 amps. I got it from that graph you linked me that's directly referring to your motor http://i365.photobucket.com/albums/oo96/SyCoQc/EV/ac_motor_img2_2.gif

Multiply the maximum input amperage by 20 and you get 640 amps .


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## Kelmark (Oct 26, 2009)

I am Converting a Replica Ferrari Dino, and I am finishing first stage, rebuilding the chasiss. Which was a 1978 VW Beetle, before I rebuild the transaxle I wanted to find out if I can improve the gearing 1-3 for the best 0-60 time and set up fourth for interstate travel. (70mph) 

Car- Kelmark GT
HPEV AC-50 and Curtis controller
Pack 115V 190AH Kokam
Peak power out to 3,600 RPM aprox 90ft pounds & 60hp

According to: http://www.bugtrans.com/transaxles2.html

Currrent Stock
*4.12 Ring Pinion*
*3.80 first*
*2.06 second*
*1.31 third*
*0.89 fourth*

What should I change?

The tire size is 25" Dia. +/- 1" as needed

The coefficeint of drag is Unknown

The converted weight will be approximately 1800lbs.

Thanks for the help!

Respectfully,

Jacob Blake
USNR


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## esoneson (Sep 1, 2008)

Jakob,

I love the Kelmark. Very sturdy construction and fabulous look. Here is a tool that can help you decide which ratios need to be changed if any.

http://vexer.com/68rt/speed.html

I use it all the time.

Eric


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## Jordysport (Mar 22, 2009)

Weight: 2205 lbs
Rolling Drag Coefficient: 0.01
Gear Ratio's:
1st===3.417:1
2nd===1.810:1
3rd===1.276:1
4th===1.026:1
5th===0.767:1
rev===2.500:1
final drive===3.765:1
Overall Tyre Circumference: 136.3
Wheel/Rim Circumference: 87.96 (14 inch wheel)
Drag Coefficient: 0.340
Air density: 0.075
Max RPM: 5700 
Max Torque (Kostov 168v Motor Running 144v): 108 

All units have been converted to your spreadsheet or matlab, could you plug them in or send me the program as i have Matlab on uni computers. 

Many thanks


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## ZX-E (Aug 31, 2009)

I've been busy wrapping up school and my motorcycle conversion over the last year, so I haven't had much of a chance to update the code. I did however add an option to calculate 0 to whatever speed your interested in, instead of just 0 to 60 times.

Is anyone still interested in the program ? Maybe someone has done something similar while I've been out of the loop. Hopefully that's the case, but I'm not sure to be honest. It will be up on the forums as an .exe early next week for sure.


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## major (Apr 4, 2008)

ZX-E said:


> I've been busy wrapping up school and my motorcycle conversion over the last year, so I haven't had much of a chance to update the code. I did however add an option to calculate 0 to whatever speed your interested in, instead of just 0 to 60 times.
> 
> Is anyone still interested in the program ? Maybe someone has done something similar while I've been out of the loop. Hopefully that's the case, but I'm not sure to be honest. It will be up on the forums as an .exe early next week for sure.


Hey Rich,

Good to hear from you  Thanks for using the program to run those calcs back on my torque thread. I thought it worked very well. And yeah, I'd like to get my hands on it.

Regards,

major


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## ZX-E (Aug 31, 2009)

Well, well. It looks like this project might be on the verge of completion. One of my parents friends owns a personal version of the Matlab compiler, so I was able to create an executable for you guys to try out. 


Unfortunately, the compiler used was the 64 bit version, so the program will only work with 64 bit windows for now. The file size with the included Matlab Runtime Compiler is also quite large, so if you already have Matlab, just download the second file without the compiler.

I'd love to write a guide how to use the program, but I don't have much spare time at the moment. I'll try to provide support if any questions come up . 

Tip #1: Right click to delete torque curve points
Tip #2: Space out torque curve points evenly

Happy tuning!


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## ZX-E (Aug 31, 2009)

64 bit windows download!
http://www.hvbikes.com/downloads.htm

New start screen:









Updated for 0-? times:


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