Quote:
Originally Posted by TomEV
After a couple of weeks I put it back to where it was. Turns out (at least with this motor / voltage / controller / vehicle weight configuration) that advancing it made it somewhat slower (7.5 seconds 0-25 compared to 7.0 standard) and less efficient (about 300 wh/mile compared to ~250 standard).
On a side note, it appears that this motor may be maxed out for this 1250 lb car.
Today I put 13” tires on the Citicar to see how it would affect speed and acceleration. For baseline, my Citicar has a top speed of 32 / 36 (normal / field weakened) and accelerates from 0-25 in an average of 7.0 seconds with 145R12 tires. (R in this configuration implies an 82 aspect ratio.)
If you just want a higher top speed, my money would be on field weakening, and a second step would be to adjust timing a few degrees positive or negative to see where your particular setup stands.
Tom
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If field weakening has an effect, a larger tire or different gearing or different voltage should have an effect.
Trouble is your WEIGHT and rolling resistance must also stay the same another battery must have added weight.
Was your amp draw the same with bigger tires? Its possible they had more rolling resistance.
My recommendation to you is to locate some geo metro 105x13" tires for $5 from a salvage yard (be very carefull mounting them), fill to 60psi (sidewall rating) and test.
What PSI do you run your tires at now? Remember their "rating" is at speeds in excess of normal highway speeds, the slower and lighter the vehicle the more air you can safely put in, if you aren't already test at a much higher air pressure, sure ride sucks but hey it does anyway? I would say 50psi-60psi, this is how I got my miles zx40 up to 30mph from 24mph.
My c-cars top speed is effected 5mph if I change from 60psi space savers to normal 40psi radials and my amp draw increases, I am sure you would see a different if you increase pressure.
Good Luck