[ZX-E]

Hi all.

I wrote a program that should help determine the ideal gear ratio for conversions. All you have to do is enter a few parameters for the vehicle and enter points for a torque curve. It outputs the 0-60 time, Top Speed and Quarter Mile. I’d love to hear what you guys think. The program obviously isn’t perfect and it has its limitations, but it does what it is designed to do: find the right gear ratio (especially useful for motorcycles).

UPDATE: The program can simulate a shift to another gear ratio at a certain RPM

If you're confused about gear ratios, tell me the input parameters on the first jpg and tell me what motor you have. I'll share the results. Hopefully the motor you're using has a torque curve somewhere. Ideally if anyone knows their vehicle's 0-60 time or quarter mile time it would be really interesting to compare the program's estimation.

After I read the post on a conversion with an AC-55 motor where people were throwing gear ratios around. I tried out a few ratios myself using the information on AzureDynamic's website's torque vs rpm curve. I actually came up with a faster zero-sixty time with a 4 to 1 ratio than a 6 to 1 because of the significant torque drop off at 2000 RPM.

azuredynamicshttp://www.azuredynamics.com/products/force-drive/documents/AC55_DMOC445ProductSheet.pdf

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


















-Rich

[major]

Originally Posted by ZX-E

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...i-36904p3.html post #23.

I would appreciate it.

major

[major]

Originally Posted by major

Any chance you might want to help us out on another thread? Look at http://www.diyelectriccar.com/forums...i-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...i-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

[ZX-E]

gThanks Major,


I might has some problems turning it into an .exe. I might 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 .

Someone post the specs for their car so I can test it please. Anyone using an AC55?

[major]

Originally Posted by ZX-E

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

[ZX-E]

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.

[Batterypoweredtoad]

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

[SolarJ]

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

[ZX-E]

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.

[SyCo]

Originally Posted by ZX-E

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/o...tor_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.