Need opinions on my battery/alternator.

[ksa8907]

So my cadillac has a digital gauge that shows charge voltage and it is almost always 14.5-14.8 volts, depending on electrical load. The only time it drops down to 13v is if I drive the car for at least an hour.

Here's the kicker, it starts fine every time. Not necessarily crisp, but it starts reliably. And I can let it sit for a day or two and I still measure 12.6v on the battery.

This is having a significant impact on my fe.

[Carbon]

Power is measured in Watts (P=V x A), not volts(V). Unless you have an ammeter (A) on your alternator, just knowing the voltage of the system is not going to tell you the load on the alternator.

The alternator in your car is PWM (pulse-width modulation) controlled, meaning the field strength varies based on demand determined by the powertrain control module. Using an under-drive pulley, for example, in this system could lead the PCM to command a stronger field strength more often, defeating the purpose of the reduced RPM.

Nice car!

[markweatherill]

14.8V is a bit high so I'd check the accuracy of the factory gauge. Otherwise it sounds normal.
There's no harm in making sure the wiring is all OK. I had a car with a corroded alternator 'sense' wire which made the alternator charge the battery at higher voltages than it needed.

[ksa8907]

I was just reading on a Cadillac forum where somebody had alternator issues and his traction control, stabilitrak, etc. lights were coming on for service. It reminded me that I did have a message to service my stabilitrak about 2 months ago. Looks like ill be looking over the alternator connections this weekend.

MET/EET degree here, i understand voltage and current just fine. up to 15.5v is normal for charging depending on state of charge and battery temperature.