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.

[tdangle]

Great thread! Never really thought about it, but you bring up a good point. A voltmeter will show if your charging system is good, but not the amount going to charge a battery. An amp meter shows the amount of charge. If you are familiar with how much charge it shows normally and the charge amount goes up, then something is asking for more -- usually the battery. Think I'll stay with the amp meter.

[canadaboy25]

Interesting, my ammeter never moves from slightly off center even when charging a nearly dead battery.

[tdangle]

Mine will show more charge after starting when the truck has been sitting a few weeks. When I do drive it around, it barely moves after starting.

[Andy4639]

Volt meter if you watch it will tell you the same thing. You have to watch them though. Ammeters are fine just don't have the movement as much as a volt meter. Basicly they do the same thing.
By the way charging a dead battery with your alternator is the worst thing you can do to your battery and alternator.

Good info on the differences of each.

https://www.quora.com/Whats-the-diff...atts-and-volts