Summary of what ELD does, from
secret way to gain a bit more mpg - Honda Civic Forum
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The civic 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.
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I myself have taken out the ELD, so whenever the engine is on, a bit over 14V are at the battery posts. I feel as though this will help increase the life of a regular lead acid battery, as it's being charged whenever I'm driving. Especially good in winter. I managed 36.6MPG on a trip to the beach in my 99 Civic DX auto with the ELD removed.
Do you think it eats much fuel? The alternator isn't working very hard to keep the battery at 14.2V.
EDIT: I don't think Canadian Civics have an ELD