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Old 02-02-2012, 08:48 PM   #39 (permalink)
ConnClark
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Join Date: Jun 2008
Location: Richland,WA
Posts: 985

Das Schlepper Frog - '85 Mercedes Benz 300SD
90 day: 23.23 mpg (US)

Gentoo320 - '04 Mercedes C320 4Matic
90 day: 22.44 mpg (US)
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Quote:
Originally Posted by aerohead View Post
We may want to think of it on a case specific basis.Those with instantaneous mpg readout could monitor mpg behavior with and without 'n see if it showed on the radar screen.
Yes I agree it would be a case by case basis, however I'm not sure that instantaneous mpg readings are going to tell you when you need to enable it.

Looking at the BSFC chart for my car I can see that enabling the alternator below normal road load (slowing down, braking, going down hill, etc) on the engine would be a loss in efficiency. It has to drop quite a ways to cross the threshold of using 15% more fuel where turning the alternator off would be beneficial. Everywhere else that it is above normal road load has better BSFC or is using less than 15% more fuel.

In my case it would be very difficult to determine where my efficiency dropped below normal enough to justify turning the alternator off would actually help.
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