Too much voltage to headlights?
nd i put a gauge on the alt just to see and once she gets up to temp, it seems to hold steady for alt output right at 14, maybe occasionally 13.9, 14.1 but never outside that range.
This is good but should not relate to temperature.
So what is going on?
During warm up the alternator is recharging the battery, and its also running at higher rpm (fast idle).
So the question is what voltage is the alternator output when;
a) the battery is recharging
b) the headlights are on
c) just running with no lights or electric accessories.
Also check if voltage of the alternator's output varies with rpm.
the car was idling and I had just started it. Didn't really seem like they're wearing out, just that they saw too much power or something.
See above.
There may be enough resistance in the circuits that causes increasing voltage loss with increasing current through the resistance.
Result is the regulator is seeing a lower voltage.
Regulator then brings the alternator's output voltage up until the regulator sees the right voltage range.
But then the output at the alternator is at significanly higher voltage.
With the relays connecting the headlights almost directly to the alternator's output, they see that high voltage and draw more current.
Voltage and amperage are not the same. Actually they are inversely proportional.
For limited power supply yes P=I x V
For an alternator Power is usually only maxed out when there is a high demand at idle rpm (slow idle).
With car/truck ammeters, the curent shown is only current to and from the battery.
When higher voltage available to the battery, it will draw more current.
So that is why the ammeter sometimes will show higher charging with higher voltage.
It could be one of two conditions.
When the battery is not fully charged, the higher the resupply voltage the more current it will draw.
When a battery is fully charged but connected to a power supply over 15 Volts current will flow through it anyway. Instead of charging it will cook off the liquid. :(
If the second is suspected, its worth checking the voltage at the battery terminal
while the ammeter is showing charge.
