Well anyways, lately my trucks headlights have been flashing upon startup. They like pulsate, dont know how else to word it. So i pulled the predator out, and my voltage is 14.7-14.8. Which i know is too high. Eventually, 10 min later the voltage is at 13.8-13.9, right where it should be...

My trucks battery is stock,(4yrs)
alternator on the other hand isn't, it failed a few months back and i replaced it w/ napa brand.

So is this an overcharging situation at startup due to my battery starting to fail, or what.

 

Sounds like the alternator.
That must be a pain to change. ugh.

 

I wouldn't change it for 13.8-14.8 volts. But I would definitely keep an eye on it with the Predator. I don't believe that it will hurt anything where it is at, voltage wise.

 

It may be that NAPA Alt. The last time I bought an alt. from NAPA it took 3 before I finally got a good one!

 

So basically i have a 4yr old stock battery. There's no undercharging going on here. I start the truck, and the battery is at 14.7 volts or so, which causes all the electronics in the truck to pulsate, i suppose due to the high voltage. I had thought that overcharging of the battery meant that the battery was weak. After a few minutes the volts settle to 13.9ish right where they should be, and stay that way until the cars shut off.........

 

14.7 Volts is normal for an alternator to output on startup. The alternator internally controls the voltage setpoint based on regulator temperature. When you initial start the truck, the alternator is cold, therefore higher setpoint. As the alternator heats up, then the setpoint gets lower. You need 14.7 volts in the winter to charge your battery.
Do you have many items turned on when the lights pulsate? This could be caused by the electrical loads exceeding the alternator output at idle, therefore you get voltage swings from 12.8 V to 14.8 and the lights will pulsate.

 

Just to give an update. I've changed nothing on the truck, and yesterday morning the battery light flicked on and off a couple times. So i pulled out the predator, logged the volts, and it was up into the 15.1 range, fluctuating down into the low 14's. So I really dont know what's going on, after a few minutes it settles to completely normal. Go figure....