Mark Dodrill wrote: > Since it is a 6.7" ADC (a bit small for my car), I suspect that I'm > having a lot of electricity turned into heating up the motor instead > of having the motor run faster (since I'm at the upper end of the > power/torque it will do).
What size car do you have? And how do you drive? It might actually be that the 6.7" motor is more efficient than a larger motor, because it operates at full load and so nearer to its peak efficiency more of the time. An oversized motor would be running at (say) half load and so less efficient (but would have more power for high speed and accelleration). > I'm wondering how I can measure this loss. If I were to measure the > air temp going into the motor and the temp leaving the motor, with a > fan of a fixed CFM blowing air through the motor (in a sealed manner), > can I use that information to figure out how many BTUs or Watts of > heat are being generated? No; this approach is pretty hopeless, for a dozen reasons. There is no such thing as a fixed CFM fan. Air is compressible and expands/contracts with temperature. Significant heat is radiated and conducted away. There is a drastic thermal time constant. Your best bet is to use the curves for the motor. Measure your actual motor voltage and current, and use the curves to estimate losses. Just be sure you keep your rpm up; don't drive in 4th gear, forcing the motor to draw high current and turn so slowly that its fan is not providing the needed cooling! -- Lee A. Hart Ring the bells that still can ring 814 8th Ave. N. Forget your perfect offering Sartell, MN 56377 USA There is a crack in everything leeahart_at_earthlink.net That's how the light gets in - Leonard Cohen
