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Old 11-26-2007, 01:02 PM   #226 (permalink)
MetroMPG
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Location: 1000 Islands, Ontario, Canada
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Blackfly - '98 Geo Metro
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01-08-2007, 04:27 Pm

Quote:
Originally Posted by SW
That must be analogous to a tourque-converter lockup clutch. EDIT: that should mean that the system should be more efficient at the equivalent of WOT.
Nice analogy!

That's one of the advantages of contactor controller setups, a la 3-stage setup in the CitiCar / ComutaCar. Notwithstanding the first speed stage (where a beefy resistor limits voltage to permit "creep" speeds), it's a 100% efficient controller approach, effectively always at WOT.

But the catch is that you're pulling high current more often with WOT, and Peukert says that'll reduce the total energy you can get from a PBA battery. Depending on driving needs/ability, you might get better range with a less efficient PWM (assuming you use the PWM to keep the amps low and accelerate gently). I suspect PWM is better for variable speed (ie: stop 'n' go) driving; and straight contactors would be more efficient in steady speed driving of longer duration.

Ideally, we want a PWM for stop 'n' go and a bypass circuit in with the Curtis for cruising efficiency (though it'll only work at one or possibly 2 speeds - 1st or 2nd gear).

Quote:
I think your system's peak current limit will determine your acceleration rate and ability to climb hills.
Oh definitely. This will be a side street-using, hill-avoiding car for sure.
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