2nd Gen Non-Engine/Transmission Charging question

[TravisG]

This morning while driving to work I noticed that my trucks voltmeter was a little higher than normal. It is usually right around 14 but today it was a little below the danger mark. ya know 18! I stopped at the store and when I came out it was back down to 14. I am not much of an electrical wiz, so where do I start? Alternator? Some sort of regulator that I don't know about or what.

 

[K5IP]

Regulator functions are performed by the pcm.

Because it takes a higher voltage to provide a comperable charge to cold battery, the temperature compensation in the pcm increases the charge voltage when everything is cold. So, I would expect an increase but 18Vdc is very high. I would verify that with a good accurate voltmeter right at the battery before jumping to conclusions.

Normal temperature compensation would increase the charge voltage by about . 25Vdc for every 10 deg C drop in temp, with a 14. 7Vdc nominal at 25degC. (-25 Mv/degC)

Even in Wi. I would not expect to see above 16Vdc

Rog