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Discussion Starter · #81 ·
Just a test version for anybody that wants to play with it. If you find issues, let me know. I'm going to play around with it for a few days then publish the final version in post #1.

Changes to Equivalent Mass done. Added Batteries in Parallel feature, and some changes to the battery table posted by drgrieve. I limited Motor Volts to the max allowed by the motor, no matter what the battery volts are. I think the only thing it would really change would be the C rate drawn from the batteries, but it's a circular reference since the voltage is calculated based on the C rate drawn. If the voltage is limited to the motor anyway, it won't matter on any other calculations.

I'm going to play around with the motor charts supplied earlier (Rickard's charts). It does seem the HV is different than the WarP11, at least different than the Netgain chart.
 

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Added the WarP 8, ImPulse 9, WarP 11, and the AC50/1238-75 to the WarP 9, just chose the number and all the relevant info will pop in.


I don't anticipate more changes unless anyone wants me to add another motor or finds errors.

Enjoy.
Warp 13? :))
 

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Just a test version for anybody that wants to play with it. If you find issues, let me know. I'm going to play around with it for a few days then publish the final version in post #1...
Joe,

What is "Continuous Peukert Factor"? It's obviously not the exponent. Are you using it in your $/mile estimate to account for energy dissipation in the battery during charge/discharge? This is significant for lead acid, especially at higher discharge currents and lower temperatures.

Nice job on the battery table - taking account of life Wh and life cost! How did you arrive at your expected life cycle factors?

I also like the calculation of cell voltage based on C rate during acceleration.

I guess Steady State Force Required is the force required to move the vehicle at constant speed?

It is not clear to me how Drive Wheel Force Available can be greater than Lbs Force Available, since the latter seems to be the force available for acceleration based on available wheel torque. Oh, the former depends on fwd/rwd, is it the max force the tires can apply to the road with static friction, before the tires would spin? Oh, looks like it is from "Traction Test".

If the vehicle is rear wheel drive, then technically there would need to be another gear ratio, that of the differential, to estimate equivalent mass of the drive shaft. Can leave that for gor to do since he wants accurate expressions for fwd, rwd, and 4wd.:D

Looks like you gained a couple seconds in 0 - 60 time with the equivalent mass correction, still well within your requirements though.

Boy, getting to be a lot of stuff in there! I've learned some tricks from your spreadsheet wizardry!
 

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Discussion Starter · #84 ·
Joe,

What is "Continuous Peukert Factor"? It's obviously not the exponent. Are you using it in your $/mile estimate to account for energy dissipation in the battery during charge/discharge? This is significant for lead acid, especially at higher discharge currents and lower temperatures.
Just a fixed amount for LA to modify the AH for range calculations (which I didn't put in yet), kind of a guess based on what I read somewhere. Since it's for LA only, I didn't want to get it too complicated because I don't consider LA cost effective for my purposes.

Nice job on the battery table - taking account of life Wh and life cost! How did you arrive at your expected life cycle factors?
Thanks! Just a guess really. From things I've read, it seems LA really lasts maybe half what it's rated at in EV's, don't really know for sure. For Lithium, it's just a guess, and a fudge factor if you have to replace a couple of batteries, maybe.


I guess Steady State Force Required is the force required to move the vehicle at constant speed?

It is not clear to me how Drive Wheel Force Available can be greater than Lbs Force Available, since the latter seems to be the force available for acceleration based on available wheel torque. Oh, the former depends on fwd/rwd, is it the max force the tires can apply to the road with static friction, before the tires would spin? Oh, looks like it is from "Traction Test".

If the vehicle is rear wheel drive, then technically there would need to be another gear ratio, that of the differential, to estimate equivalent mass of the drive shaft. Can leave that for gor to do since he wants accurate expressions for fwd, rwd, and 4wd.:D
Yes; yes; yes; I hope no one would notice :eek:, it should be very small though; and yes let's let gor figure that out for us! :D

Since wheels, tires and flywheels would be the most likely things someone could change to make a change in acceleration based on rotating mass, it'd be nice to leave just those in the spreadsheet and have the other rotating components Eq Mass based on vehicle mass, like in HPWizard. Maybe a future revision.

Looks like you gained a couple seconds in 0 - 60 time with the equivalent mass correction, still well within your requirements though.
I must have changed a few things on my car from my sheet in post # 1. I'm showing a loss of about 0.3 seconds if I'm only using 3rd gear for starts. I think I found 1st gear had too much wheel spin.

Boy, getting to be a lot of stuff in there! I've learned some tricks from your spreadsheet wizardry!
Cool! It's nice to have someone checking these things out. Hopefully it can be helpful to others.
 

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"If the vehicle is rear wheel drive, then technically there would need to be another gear ratio, that of the differential, to estimate equivalent mass of the drive shaft. Can leave that for gor to do since he wants accurate expressions for fwd, rwd, and 4wd"
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"and yes let's let gor figure that out for us! "
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yea, right : ))))) - you don't wanna know... the more i digging there - the less i like it
for now - hp wiz f-la - just fine :D (mid. of drivetrain: diff-gear box ~ most constant % - less affected by gears like top and bottom)
i guess i'll put it in separate thread - too much info
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"Since wheels, tires and flywheels would be the most likely things someone could change to make a change in acceleration based on rotating mass, it'd be nice to leave just those in the spreadsheet and have the other rotating components Eq Mass based on vehicle mass, like in HPWizard. Maybe a future revision."

- right (+ clutch & propshaft),- just take word "guesstimate" out - it's estimate, examples and links can be added for reference in the bottom

p.s. again - very nice spreadsheet, Max, congratulations
 

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Couple things...I used the C sub i parameter in the "porsche" version of Joe's spreadsheet and it gave a 0 to 60 time a couple seconds longer (10.20 versus 9.26) than that predicted by the calculation using equivalent masses.

I also tried reducing 0.0025 to 0.002 in the equation using C sub i in my spreadsheet and it further underestimated the 0 to 60 time, so wrong direction. It gave 9.75 sec in Joe's sheet.

It's easy to use the C sub i parameter in Joe's spreadsheet since a = F/(C sub i)m, where m is the total translational mass of the car, M1, in Joe's "porsche" version. So for example entry S44 becomes Q44/(M$1*J$31) in place of Q44/(M$2+R44).

I wonder if the 0 to 60 times reported in articles are achieved by reving the engines and popping the clutch, which makes it different than my time which was recorded by starting from zero mph and zero rpm, though not as different as it would be if my car had an ice.

Gor, what discrepancies are you seeing for the 0 to 60 times you pulled off the net? Are they over or under estimated, or a mix? How do the predictions compare for front wheel drive versus rear wheel drive? How do you know the numbers are accurate? Edit: Also, how are you using the C sub i parameter or equivalent mass to calculate acceleration, do you have torque-speed curves for the cars?

For my car the C sub i parameter gave 0 to 60 time about 13% less than measured, which I figured was good enough considering the uncertainties, but it may just have been coincidence for that one result. I think +/-15% agreement for a number of different cars would be very good considering...
 

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Couple things...I used the C sub i parameter in the "porsche" version of Joe's spreadsheet and it gave a 0 to 60 time a couple seconds longer (10.20 versus 9.26) than that predicted by the calculation using equivalent masses.

I also tried reducing 0.0025 to 0.002 in the equation using C sub i in my spreadsheet and it further underestimated the 0 to 60 time, so wrong direction. It gave 9.75 sec in Joe's sheet.

It's easy to use the C sub i parameter in Joe's spreadsheet since a = F/(C sub i)m, where m is the total translational mass of the car, M1, in Joe's "porsche" version. So for example entry S44 becomes Q44/(M$1*J$31) in place of Q44/(M$2+R44).

I wonder if the 0 to 60 times reported in articles are achieved by reving the engines and popping the clutch, which makes it different than my time which was recorded by starting from zero mph and zero rpm, though not as different as it would be if my car had an ice.

Gor, what discrepancies are you seeing for the 0 to 60 times you pulled off the net? Are they over or under estimated, or a mix? How do the predictions compare for front wheel drive versus rear wheel drive? How do you know the numbers are accurate? Edit: Also, how are you using the C sub i parameter or equivalent mass to calculate acceleration, do you have torque-speed curves for the cars?

For my car the C sub i parameter gave 0 to 60 time about 13% less than measured, which I figured was good enough considering the uncertainties, but it may just have been coincidence for that one result. I think +/-15% agreement for a number of different cars would be very good considering...
for EV performance calc, i make donor perf. model (with ice torque curve) to have data before and after conversion

w/o inertia accel times are less than published, with MOI - more;

true, on the magazines testing - they do revving engine, slipping clutch, using tire slip etc - whatever works to get better time, abusing tested vehicle just shy from braking it
this would take care of MOI on low gear, isn't it? : ))
but i don't have enough data to come with fwd, rwd, awd MOI numbers

launch 0-20 mph - gray area, too many things will vary, with clutch or with torque converter in AT...
many performance calc. don't even want to get blamed and start count from 30 mph : ))))

http://vlsicad.ucsd.edu/~sharma/Potpourri/perf_est.html
 

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for EV performance calc, i make donor perf. model (with ice torque curve) to have data before and after conversion

w/o inertia accel times are less than published, with MOI - more;

true, on the magazines testing - they do revving engine, slipping clutch, using tire slip etc - whatever works to get better time, abusing tested vehicle just shy from braking it
this would take care of MOI on low gear, isn't it? : ))...
I think so...and that is where the effect is largest. For example, the C sub i parameter (1 +0.04 +0.0025g^2) for my car is 1.49 in first gear, 1.17 in second, and 1.10 in third, so only a 10% effect in third. In my car, starting in second gives worse performance than starting in third, despite the lower effect of moi, because the decrease in mechanical advantage, 1.88, and resultant wheel torque is greater than what you gain in reduced moi, 1.27.
 

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It occurred to me that I had included drive train efficiency in the calculation of range, but not in the calculation of available acceleration. Using the value suggested by Bob Brant, 90%, (since I don't know what it would be), it increased my calculated 0 to 60 mph time from 13.2 sec to 14.8 sec. If I add 1 sec for shifting twice it gives 15.8 sec versus the measured time of 16 sec. May well be serendipity, but you couldn't ask for much better agreement than that!

I did the same for the AC31/Curtis 1238-7501 in my car and got 15.25 sec, but I have to shift three times rather than 2 so pick up an additional about 1/2 sec, so 15.8 versus 16.75 sec total, AC50/AC31. Doesn't seem to be much difference between them.
 
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