Let's see...The difference between a 100% battery
and a 0% battery
is all of one volt, from 11.7 to 12.7 more or less. You're talking about taking a 12.7 battery and dropping either 3% or 10% to your light bulbs, that would change the voltage to 12.3 or 11.43.
The bulbs will last longer, but do you really want to run bulbs at 11.43 volts, when they are designed to run at 14.4 volts (alternator voltage) not '12' in the first place?
I wouldn't bother ripping out good wiring
to upgrade it, but if I was laying new wire--I'd spend for the thicker stuff. Once you buy good crimp connectors and all the other stuff, the difference in the wire isn't much of the total damage anyway.<G>
Same thoughts for the battery cables
. If you are installing new, run the numbers and buy the thickest you can. Cable terminations (having the lugs properly crimped and secured tight and clean) can make as much difference as the cables
, so make sure they are made up correctly not just squashed on.
If you consider that every 1/10th of a volt lost
in the battery cables means your engine/alternator/charger are going to have to work harder to beat that cable loss, every time, the cables seem cheaper compared to the fuel
they can save, too.