[paulgato]

Hi again,

I've had good success with running alternator-optional. In fact I've barely used the alternator since January. I plug the car into the mains every night on the driveway, have a 10A charger installed in the engine bay, and have a large AGM battery installed. For the vast majority of my daily driving this works fine and I don't need the alternator. I have cut one small wire close to the alternator, and fitted an inline plug/socket, so if I do need the alternator I just reconnect that wire. (I'll fit a switch on the dash at some point, but I use the alternator so rarely it hardly seems worth the trouble.)

I reckon I'm saving about 10% on fuel from ditching the alternator. Since I'm plugging the car in every night I also fitted a 2kw engine coolant preheater, which I switch on from indoors via a remote control fob thing an hour before driving off. I reckon that saves me another 5% overall. Obviously the shorter the journey the greater the benefit of pre-heating. According to the pumps, my overall mpg has jumped up from about 70mpg to about 80mpg since plugging in every night. That's a 15% improvement, and I'd say that's being conservative.

I've spent a lot of time working on this mod, and quite a lot of money too, mainly trying to extend the alternator-free driving range to the point where I would never need the alternator (second battery in the rear, DC/DC converter, etc...) but in fact the majority of the benefit can be had by simply fitting one really good battery in the engine bay and an appropriate battery charger. 10% off your fuel bill is a fair amount, so this is a mod that will pay for itself quite easily if you do any number of miles in a year.

Of course it only works if you have a driveway - somewhere you can plug in every night.