Deceleration Alternator

[bbjsw10]

I was thinking tonight about making my alternator kill, into a deceleration alternator. Would give me atleast a couple extra miles of run time that way.

I am using a Potter-Brumfield 70a relay to disconnect the output, and a Bosch 30a relay to kill the field wire. I was thinking of putting in a switch like this.
Nitrous Oxide Systems (NOS) 15640NOS - NOS Micro Throttle Switches - summitracing.com
on the throttle to be activated at idle position, but also connected to the clutch pedal through a set of relays as well, Basically only allowing it to run alternator when clutch is engaged and throttle is at idle. This way avoiding pretty much all conditions except for neutral idling, and deceleration.

I figure if the car is idling it might as well be doing something, and DFCO sounds like a good time to charge the battery to me.

Suggestions? If it sounds feasible I could possible get some diagrams started and a How-to. I have it stuck in my brain and need to get it out.

[Bakerboy]

Sounds like a good idea but if your clutch is engaged you won't be in dfco, your car will just be idling like in neutral. DFCO occurs when you coast in gear above a certain rpm range- in my car it kicks out of dfco at about 900 rpm.

[bbjsw10]

Clutch engaged while driving, dis-engaged while coasting, shifting.
http://en.wikipedia.org/wiki/Clutch

[MetroMPG]

"Smart" alternator control is a valid approach - it's been used (and is being used) on many models. BMW comes to mind, with its "efficient dynamics" program.