"The alternator's load on the engine is the alternator belt."
Actually, since the belt doesn't get real hot, it's not dissipating much power at all.
The electrical load (lights, rear window defroster etc) is what loads up the alternator and
that (now mechanical) load is placed on the engine via the belt.
" Removing the alternator belt and running the engine just off the battery will shorten the battery life."
tommyt31 did say he was going to replace the battery with a deep cycle
so, maybe his idea will work ok..
"Draining down the battery and then periodically turning on the alternator with a switch to recharge it might shorten the life of the alternator."
If he watches the battery voltage and doesn't allow it to get too low, recharging it with the alternator shouldn't cause an abnormally high load.
Since tommyt31 is going to charge up his battery at night off the AC mains, it seems to me
that the alternator is going to get less use and should last a lot longer.
"Turning the alternator on and off with a switch would not affect mileage because the engine is still turning the alternator via the alternator belt."
If he is removing all the electrical load off the alternator, it's going to be real easy to turn.
(When you have the lights, etc turned on, it takes more work to turn the alternator,
to generate power: Watts)
And if the engine is not doing as much work, then he should get better MPG..
"whenever sensors detect the electrical load has increased when the engine is at idle. Turn on the headlights at idle and the engine will automatically speed up to increase the alternator output to the battery so the headlights don't start draining the battery."
My take on that is, when you turn on the lights, you electrically load down the alternator,
it loads down the engine, which has an idle control unit which wants to keep the engine
from stalling (when RPMs drop too low), so the idle control gives the engine more gas..
Any time tommyt31 charges his battery at home, he is not using gasoline..
His car will be working like a Plug-in Hybrid. But not saving a ton of gas
like the real deal (Honda Insight)!!
But, it sure seems like he will be saving a small amount of fuel..
Most likely not an easily measurable amount!