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Old 05-25-2009, 10:07 AM   #9 (permalink)
EcoModding Apprentice
Join Date: Jun 2008
Location: Cambridge, ON
Posts: 240

Jalilah - '07 Chevrolet Cobalt LT
90 day: 40.57 mpg (US)
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I've often thought of replacing the alternator with a deep cycle battery, and a large series of peltier modules that run off of the exhuast. The exhuast gets really toasty (especially if you wrap it upstream) and there is this beutiful supply of cold air running along most of it for the cold side heatsink.

Problems i can see with this?

1) You'd have to run two modules in series, possibly three to get to 15V which is about where you'd have to be to completely replace the alternator
2) You'd have to integrate your own smart charging circuitry. Charging at 15V at all times would place an undue strain on your battery, and you'd be chewing through batteries every few years (which i guess isn't terrible)
3) If you were doing a lot of short trips, you'd run into issues.
4) I have no idea how much power would be required. Most i could see you generating in this fashion would be 500w (ish) and that would be a LOT of modules
5) You would have to engineer the thermal coupling to the exhuast to ensure that the peltiers didn't approach the melting temperature of the solder used to create the junctions

If anyone knows what kind of load it takes to run a car, i'd be curious.
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