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Old 03-15-2012, 10:12 PM   #8 (permalink)
MetroMPG
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Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
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Blackfly - '98 Geo Metro
Team Metro
Last 3: 70.09 mpg (US)

MPGiata - '90 Mazda Miata
90 day: 52.8 mpg (US)

Winter beater Metro - '00 Chevrolet Metro
90 day: 73.57 mpg (US)

Fancy Metro - '14 Mitsubishi Mirage top spec
90 day: 58.72 mpg (US)
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My understanding is that the HF model (and Civic VX) had the special alternator.

Quote:
- The high efficiency Honda Civic VX and CRX HF models reduce alternator charging under certain cirucumstances. The VX computer instructs the alternator to drop from 14.5 volts to 12.5 (ie. not charging the battery) when all of the following are true:
- Load below 10A
- Speed below 40 MPH
- Engine speed below 3600 RPM
- Coolant temp above 140 F
- A/C off
- Intake air temp above 65 F
- Brake switch off
- Fuel cut-off not active
In other words, the alternator is essentially "idling" when the load on it is low, the car is warmed up and being driven gently. Note that the alternator reverts to normal charging when braking or decelerating (fuel cut-off mode), which is like a simple form of regenerative braking found in modern hybrids and electric vehicles.
Plug-in Blackfly: going alternator optional nets +10% mpg - MetroMPG.com

Info came from EcoModder member Randy. I forget which one
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