Paul Dove wrote:
When I built mine I did a spread sheet.
Ben Goren via EV wrote:
Any chance you have a copy handy and would be willing to share?
Here is a copy of the Excel spreadsheet I use for my performance
calculations. This is a "dead" version for email purposes (filled out
for my 1980 LeCar / Lectric Leopard EV), but it shows the equations for
the calculations. Ben, I can send a "live" version to your email address
if you like (let me know off-list).
Renault LeCar HP vs. Speed Calculations by: Lee Hart
HP = rolling resistance + power train loss + aerodynamic drag
where rolling resistance = R W V / 375
R = tire roll resistance 0.008
W = vehicle weight, lbs. 2306
V = velocity, mph 5
power train loss = C W V^2 / 375
C = loss coefficient 0.0002
I^2R, gear, bearing, stirring etc.
aerodynamic drag = Cd A V^3 / 146,625
Cd = drag coefficient 0.35
A = frontal area, sq.ft. 18
motor ADC L91 15 HP at 96 volts and 135 amps = 86% efficiency
batteries 12 Concorde 12 v each weight (lbs) 63
33% of curb wt 144 v total amp-hrs (20-hr rate) 95
175 minutes at 25 amps Peukert amp-hrs 104
621 minutes at 8 amps Peukert exponent 1.11
MPH 25 30 35 40 45 50 55 60
MotorHP 2.67 3.74 5.07 6.69 8.62 10.91 13.57 16.66
Eff. 66% 72% 77% 81% 84% 85% 86% 86%
WattsIn 3039 3863 4892 6160 7701 9554 11762 14373
Amps 22 28 36 45 56 70 86 105
Minutes 200 153 118 91 71 56 45 36
Miles 83 77 69 61 54 47 41 36
A spreadsheet makes it easy to play "what if..." games. What if I add a
battery? What if I change from lead-acid to lithium? What if I reduce
the weight, or improve aerodynamics, etc.
--
A designer knows he has achieved perfection not when there is
nothing left to add, but when there is nothing left to take away.
-- Antoine de Saint Exupery
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
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