Another EV Calculator, in oooBasic

I tried it but I can't open the file- it says it has been locked and password protected.

 

I'm using OpenOffice 3.1 on Linux Fedora 12 and have no problem with it.

Eric

 

good with me as well (open office 3.1)

 

Some views of my EV Calculator

 

Are you sure the file got updated in your edit?

Excel still tells me:
Cannot open 'Franky EV Calculator.ods': This file has been protected with a password and cannot be opened.

I'll try later with OO, but I downloaded it a machine that doesn't have that installed.

 

Yes TX DJ

To be sure, I've downloaded it and checked. It has document protection removed, but still has a sheet protection (necessary to avoid messing it all up)

It runs well on OpenOffice (I have version 3.2).

I'm not sure you can run it with Excel, as it makes great use of oooBasic macros.

 

How do I change the pack topology to say 45S - 1P? Also, if the pack voltage is set real low, shouldn't the Speed be limited?

 

I figured out the 45 cell thing. My macros weren't enabled.

 

Nice you found it. I've preparared a screenshot, just in case, for other people.

 

The formula I use to compute acceleration time is too optimistic, as it consider acceleration constant. Does anyone as a good formula ?

It should be an integration of :

dt = m v dv / (Pmax - ½ ρ Ca A v3 -( μ m g + m g sinα ) v)

 

The formula I use to compute acceleration time is too optimistic, as it consider acceleration constant. Does anyone as a good formula ?

It should be an integration of :

dt = m v dv / (Pmax - ½ ρ Ca A v3 -( μ m g + m g sinα ) v)

Acceleration is definitely not constant. And unless you're only using direct drive you'll need to consider gearing.

I used F=m*(v1-v2)/t or t=m*(v1-v2)/F, the F being what the motor can deliver to the tire patch, less F required at speed (and inclination in your calculations). I used 5mph increments, looks like accuracy should be within 5%.

You really should include what force the tires can deliver to the pavement, since it looks like a friction coefficient of 1 for dry pavement is pretty close to all you'll get. I'm toying with this in my spreadsheet now.

Download the spreadsheet in my signature, you should be able to figure out everything.

 

maxvtol : I've read the entire thread and downloaded your spreadsheet, but I'm to figure out what are the formulas as I only understand metric.

 

I haven't done a detail check of the units in your formula, but at first glance it looks ok. It's just for average power over a increment in velocity. You can't use the maximum power of the motor for this, you'll have to use the average power over that increment in velocity, and to find this you'll have to use a motor chart to find the power at your start velocity and end velocity and average that power. You'll need the rpm for this, that's why you'll need the gearing ratios. Then you can just add the times for each velocity increment for an ET.

My formulas are in the cells, mostly under the acceration chart, although I'm using F instead of the P/v in your equation, but same thing. My spreadsheet is more taylored to finding maximum acceleration, but let me know what you're trying to do and I'll help any way I can.

 

I've done some work to implement gearbox in another sheet (Motors).

All is not perfect, still need some work to do.

But you can choose gear ratio, change gear, or take rid of one or more gear, and see what happens.

Obviously, You'll better have a big powerfull motor and only one reduction gear.

 

Job finished, and updated V2.

All things in a signle sheet, and more coherency among diffrents formulas.

Take into account, motor torque, gear.

EDIT : BUG correction, graphic has sometime incorrect size
some simplification

EDIT : Added shift time

 

My ev calcultor now takes care of : power, C rating, DOD, gearbox ratios, shift time, grade.

I've updated the file in the the first post, and make some cleaning.

 

My EV acceleration calculator...

Determine the power to weight ratio, using estimates for actual voltage and motor efficiency. Find an ICE car with that power to weight ratio and use its numbers. Expect to do a little better in the real world because electric motors have wider power band compared to most ICEs. Follow up with construction and driving to see for yourself how good your calculator is

Yes, that means that most golf cart battery powered EVs end up performing like 36hp or 40 hp Beetles.

 

Change mileage to wh/km and some optimization.

Update in first post

 

A few suggestions.

I can only download the zipped file, then open it (only opens as read only), I have to do a "Save As" then use that file to get it to work. If that is the way it's supposed to work, I would put that instruction in post 1 where you download it. Other instructions on how to use in the spreadsheet itself would be useful, either on a separate page or on the flyovers. Somehow marking where the dropdowns are would be nice.

Label the x and y axis on the graphs with the units.

There's no way to adjust motor voltage or amperage which affects performance, this is done with the controller settings on my spreadsheet. To give a realistic performance, that should be included, at least on DC motors. On AC, I'm not to sure how it would be done, but if it requires a certain voltage or amperage battery pack, you could default a battery setting. And I'm curious as to how you're getting your motor charts.

Put the acceleration in G's. In toying with my spreadsheet, if you have close to a 50/50 weight distribution, you'll probably only get roughly 0.5 G's acceleration (more for RWD, less for FWD). If the acceleration shows more than 0.5 G's for a particular motor, it's probably not realistic (at least on a 50/50 weight distribution with similar tires on front as on back).

 

Hello Max,

The file is not read-only, is't just zipped, I thought is was the best extension permited by the forum.

OK for the labels, big mistake i'll correct soon.

As this spreadsheet is just a simulation program, I need formulas and "boundary conditions" to program the effect of changing the nominal voltage.

For now, I only use datas I've found in available torque curves, with only 3 points : 2 for the flat torque portion, and 1 for the max rpm. Maybe I can add some more columns to take care of voltage ranges.

I've found these datas sufficient to emulate a torque and power curve, with a correlation function.

I'll check your spreadsheet to understand how you deal with acceleration and weight distribution , I've not seen anything about that before. I suppose the simulation I give is for an ideal 50/50 weight distribution, but with correct datas entered it give 4.0s for 0-100km/h and 190km/h max for the Tesla. Not far from the real numbers.

Thank's for your sugestions.

 

Quite a long time I've updated this EV calculator, it's now based upon torque curves.

 

Looks good. I probably should have checked it to see if the acceleration portion was working before I posted. If my guesstimate is correct the only thing you could add is a hard limit to your top speed based on motor speed versus gearing. Given the initial values in your script the car shouldn't be able to go above ~160km/hr given the ~7300rpm limit of the HVH250.

 

Hello roflwaffle, if you set the rpm limit to 7300 in the Motors rpm table, with a 1575 kg car, a 3.70:1 reduction gear ratio (direct drive), and other defaut parameters, the speed limit is 160 km/h.

But I have the Remy HVH motor spec sheet that set max rpm to 10600.

Remy HVH 250

Anyway, max speed will depend of numerous factors. I don't know what car you plan to convert.

 

In that case it looks like your chart for motor speed is being cut off at row 73 for some reason. Nice calculator btw. Have you thought about incorporating motor efficiency curves into it? That way someone could see the difference between motor efficiency at various speeds/loads wrt gearing.

 

In fact, I use the table on the right side, only to display the graph, the actual calculations are done via the left side of the table, where I conceptualize the motor torque curve with only two points.

Rought approximation, but every thing is approximate here !

By the way you can change the graph resolution by changing the "blue" parameter " Δrpm
By default it's set to 150, try 200 or 250...

I don't plan to have motor efficiency, or motor performance based on the voltage at the moment, one day maybe...

Regards

 

Great spreadsheet! Did my head in a little bit when I first opened it, but all good.

Some additions that would come in handy for Australian and New Zealand users, if you feel like adding them in a future update:

Gearbox:

• As fitted to Holden Gemini (TX, 1976)
  
  • M20 4-speed
    • 1st: 3.51:1
    • 2nd: 2.17:1
    • 3rd: 1.42:1
    • 4th: 1.00:1

• As fitted to Holden Gemini (TG, 1983)
  • M75 5-speed
    • 1st: 3.51:1
    • 2nd: 2.17:1
    • 3rd: 1.42:1
    • 4th: 1.00:1
    • 5th: 0.86:1
  • M40 3-speed Trimatic
    • 1st: 2.31:1
    • 2nd: 1.46:1
    • 3rd: 1.00:1

• As fitted to Holden Commodore (VB, 1978)
  
  • 4 speed MC6 2.85 and 3.3 L6 Manual Transmission
    • 1st: 3.50:1
    • 2nd: 2.02:1
    • 3rd: 1.41:1
    • 4th: 1.00:1
  • 4 speed Torquemaster M20 2.85 and 3.3 L6 Manual Transmission
    • 1st: 3.05:1
    • 2nd: 2.19:1
    • 3rd: 1.15:1
    • 4th: 1.00:1
  • 4 speed M20 4.2 V8 Manual Transmission
    • 1st: 3.05:1
    • 2nd: 2.19:1
    • 3rd: 1.15:1
    • 4th: 1.00:1
  • 4 speed M21 5.0 V8 Manual Transmission
    • 1st: 2.54:1
    • 2nd: 1.83:1
    • 3rd: 1.38:1
    • 4th: 1.00:1
  • 3 speed TriMatic M40 3.3 L6 and 4.2 V8 Automatic Transmission
    • 1st: 2.31:1
    • 2nd: 1.46:1
    • 3rd: 1.00:1
  • 3 speed TurboHydramatic 350 M41 5.0 V8 Automatic Transmission
    • 1st: 2.48:1
    • 2nd: 1.48:1
    • 3rd: 1.00:1

• As fitted to Holden Commodore (VN, 1988)
  
  • 5 speed Manual M78 V6 Transmission
    • 1st: 3.25:1
    • 2nd: 1.99:1
    • 3rd: 1.29:1
    • 4th: 1.000:1
    • 5th: 0.72:1
  • 5 speed Manual M78 V8 Transmission
    • 1st: 2.95:1
    • 2nd: 1.94:1
    • 3rd: 1.34:1
    • 4th: 1.00:1
    • 5th: 0.73:1
  • MD8 4 speed Turbohydramatic 700 Automatic Transmission
    • 1st: 3.06:1
    • 2nd: 1.62:1
    • 3rd: 1.00:1
    • 4th: 0.70:1

• As fitted to Ford Falcon (XD, 1979)
  
  • Manual (Six, 3 speed Borg Warner)
    • 1st: 2.95:1
    • 2nd: 1.69:1
    • 3rd: 1.00:1
  • Manual (Six and 4.9 litre V8, 4 speed)
    • 1st: 3.06:1
    • 2nd: 1.84:1
    • 3rd: 1.32:1
  • Manual (5.8 litre V8, 4 speed)
    • 1st: 2.36:1
    • 2nd: 1.78:1
    • 3rd: 1.27:1
    • 4th: 1.00:1
  • Manual (5.8 litre V8, 4 speed)
    • 1st: 2.46:1
    • 2nd: 1.78:1
    • 3rd: 1.27:1
    • 4th: 1.00:1
  • Automatic (3.3 and 4.1 litre Six; Borg Warner 35-3)
    • 1st: 2.39:1
    • 2nd: 1.45:1
    • 3rd: 1.00:1
  • Automatic (3.3 and 4.1 litre Six, 4.9 litre V8; C4-3)
    • 1st: 2.46:1
    • 2nd: 1.46:1
    • 3rd: 1.00:1
  • Automatic (5.8 litre V8; Ford FMX-3)
    • 1st: 2.40:1
    • 2nd: 1.47:1
    • 3rd: 1.00:1

• As fitted to Ford Falcon (EB GT, 1992)
  
  • BTR 5 speed overdrive Manual
    • 1st: 3.35:1
    • 2nd: 1.99:1
    • 3rd: 1.33:1
    • 4th: 1.00:1
    • 5th: 0.72:1
  • Type: BTR 4 speed overdrive lock up torque convertor
    • 1st: 2.39:1
    • 2nd: 1.45:1
    • 3rd: 1.00:1
    • 4th: 0.68:1

Once you've got a dozen or so gearboxes listed, maybe put them on a seperate sheet as well? In fact, you could probably push the Motors 'boxout' onto a seperate sheet as well, and leave the dropdown box on the main sheet. If you move the Motors dropdown to the top right, and shift the 'boxout' with the Gearbox dropdown in it to the right of screen as well, and that would let you widen the columns for Power, Uptime, Range, etc.

Cd (according to Wikipedia):

• 1995 (XG) Ford Falcon:0.31
• 1998 (EA) Ford Falcon:0.295
• 1998 (VT) Holden Commodore: 0.31.

Could you add some RPM/Torque specs for Kostovs motors as well (like the 17R 144V, Dual 17R 144V, R20 192V)? Their graphs do my head in.

 

Spent some time with this spreadsheet this morning. Very, very handy. I'd previously conservatively estimated a conversion to get 300wH/km at highway speeds. You spreadsheet is suggesting I'll be 'sipping amps' at a miserly 147wH/km and less, which doubles my range, so I'm somewhat suspicious that I've done something wrong.

Specs:
~1000 kilo car after conversion. 900 kilo ICE-standard weight, ~150kg engine, ~50kg ICE ancillaries, add back in a 200kg battery pack, M75 gearbox.
65 100AH Sky Energy cells, 65P1S, 70% DoD (15kWh pack).
0.3C[sub]d[/sub].
0.5s shift time.
Impulse 9.

This gives me a range of 262km @ 30kmh and 59wH/km, 206km @ 60kmh, 75wH/km, and 119km @100kmh, 129wH/km. The Range is so far in excess and the Mileage so far below my estimates that I'm sure I've done something wrong to the spreadsheet!

EDIT: just figured out the 15kWh was useable capacity, not total capacity. With 46*100AH @100% DoD, my range is now 'only' 122km @ 100kmh...?

If the figures the spreadsheet are giving me are correct, I can almost halve the size of the battery pack (smaller batteries, but keep the voltage up), cutting perhaps a third off the cost of the conversion.