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Old 08-25-2009, 08:40 PM   #31 (permalink)
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Join Date: Nov 2008
Location: Troy, Pa.
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Pasta - '96 Volkswagen Passat TDi
90 day: 45.22 mpg (US)
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Quote:
Originally Posted by jamesqf View Post
Maybe your car doesn't, but all of mine (excluding the Insight, of course) have run just fine on 12V, as for instance engine-off coasting, or when an alternator goes out.
SO you don't think that voltage sag occurs then? 'Cuz I hate to break it to you, but almost as soon you start running off your battery alone, you're not running on 12V anymore.

By the way - your 12V battery, when fully charged, contains something closer to 13V. It's 12V *nominal*. Test it some time.


Darin -

The conversion factor for your car's lost HP will be quite different, obviously, because the vehicle in question was probably running very high-tension ignition system, high power fuel systems, and making something close to 1000+ HP. At that point, you could imagine that for each 1VDC from 14.5VDC, they'd lose 10HP or so... for a 1% efficiency loss.

Applying that to your car, assuming you have the same draw as that engine has - You'd only be losing 2.5% of available HP, in your case, a figure not even noticeable by multi-dyno testing. Of course, the calculation for HP loss will not be linear, either.

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