Ammeter or Voltmeter?

[RichardJ]

Some have discussed the value of one over the other on this forum in the past.
I have sometimes posted that I thought the Ammeter was more useful.

The Ammeter normally always sits in the middle. at 0 Amps, within a second of starting after replacing the current lost from the starter motor. This is normal for all charging systems with an Ammeter.

Three weeks ago My GMC Ammeter started showing a slight charge while driving down the road. Battery voltage was 12.2 V after the truck sat a few hours. Charging voltage was 13.5 - 14.0 V at just above idle.
One battery post didn't look right so I pulled the cable and cleaned it. Oxidized, but not corroded. After a few days the Ammeter stopped showing the charge and went back to normal.

Yesterday while out making a few stops, during one of the restarts, the starter cranked noticeably slower.

Today I hauled some firewood over to my son-in laws, then made a trip across town. All the way over and back , the Ammeter was on the first of the two marks on the charge side.


To sum up all that rambling,

The ammeter showed a slight charge for a few days, went bake to normal for a few weeks, then started showing a higher charge.

Conclusion,
The battery is about ready to leave me sitting somewhere looking for a jump.

The shocker,

I've been buying Sears Diehard batteries for many years. The guy looks at it and says he hasn't seen that old a label in many years. He looks up on his computer and says it shows that I've bought batteries for the Vette and the MH, but haven't bought a battery for the GMC in 13 YEARS.

I knew it was old, couldn't find the receipt and have no recollection of when the last time I replaced it, but 13 YEARS.

10DN with external regulator, HEI and AC.

To stick with the original topic, the Ammeter has always told me when it was time to replace the battery before I was stranded somewhere, even if it takes 13 years.