10-16-2008, 08:35 PM
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#1 (permalink)
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Batman Junior
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Tesla Roadster a power hog?
Tesla founder & former exec Martin Eberhard has posted on his blog about how shocked he was  to discover how much power his car wasted sitting idle (battery coolant pump running constantly):
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Whoa! The car consumed a whopping 14 kilowatt-hours in four days, just sitting there! Doing the math, the pump draws about 146 watts all day long, all night long, every day. This works out to 1,278 kWh per year. To put this in perspective, a really nice 26-cubic foot side-by-side refrigerator with an ice maker uses only 618 kWh per year, so this pump is the energy-equivalent of two huge refrigerators!
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The car basically wastes about 20% of its battery capacity (and lifecycle) circulating coolant. Note this is for HIS particular driving patterns & style; YMMV.
He's also been tracking his total efficiency, at the wall: 439 watt hours/mile
That's right: turn on four (point 39) 100 watt light bulbs for an hour, or drive 1 mile. Your choice.
This includes the "idle wastefulness" that he discovered, and is frankly not very good.
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10-16-2008, 09:40 PM
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#2 (permalink)
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Administrator
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Yikes, looks like someone needs some lessons in ecodriving!
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10-16-2008, 09:59 PM
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#3 (permalink)
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Batman Junior
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Likely. But then that'd be like trying to teach a Ferarri driver to ecodrive. Probably ain't gonna happen.
For comparison, the ForkenSwift's average over winter & summer is 312 watt hours / mile (at the wall).
Its built-in "efficiency hit" comes from having worn out batteries. If they were newer, it'd be better than that.
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10-16-2008, 10:25 PM
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#4 (permalink)
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Batman Junior
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More perspective: Eberhard's lousy 439 Wh/mile is still 76 MPG equivalent. Compared to the Ferarri, OK, not too shabby.
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10-17-2008, 11:34 AM
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#5 (permalink)
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EcoModding Lurker
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Quote:
Originally Posted by MetroMPG
More perspective: Eberhard's lousy 439 Wh/mile is still 76 MPG equivalent. Compared to the Ferarri, OK, not too shabby.
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Under what equivalency? I get 83 mpg for pump energy versus plug energy. However, it only ranks 57 mpg in terms of price equivalency. I get a measly 33 mpg in CO2 equivalency, using the average US power mix. |
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10-17-2008, 12:25 PM
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#6 (permalink)
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Batman Junior
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Energy conversions used:
- 3412 BTU per kWh
- 114,500 BTU per gallon (US)
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10-18-2008, 02:59 PM
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#7 (permalink)
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EcoModding Lurker
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Ok; I was using 34.8 MJ/l, apparently from Oak Ridge National Lab, via Wikipedia. 114,500 BTU/gallon is 31.9 MJ/l, which explains why our numbers differed.
I really hope they're going to bring their efficiency up. That 33 mpg CO2 number could be quite damaging to its eco-reputation were it widely known. The trickle-down effect the smaller EV players wouldn't help matters either, even if their efficiencies were higher.
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