Battery resting voltage 12.8V when truck is off. Is that ok?
 

This past sunday I drove around 40 miles and did an all day hike. Got back to the car 8 hours later and it started right up. I drove 5 miles to a restaurant and when I got back in the truck 40 min later it would not start. The battery was completely dead.

I got it jumped and the 40 mile trip home the truck would stall for half a second and come back on. It did this 4 times on the way home.

I pulled the old battery and put in a brand new battery. I then wire wheeled every pos and ground going to the battery at the terminals and the ground to fender to make sure all connections are good.

I drove into work this morning and I watched my Scangauge II. the voltage put out while driving is 14.0-14.1V.

When I turned off the truck and went into the building it read 12.8V.

Is a resting 12.8V correct? Or do I need to start checking other connections and the alternator?

(483,333 miles, 2008 Sport Edition 4.7L V8)

Yes this is what it should be, the system is 12 volts. Less is discharging more is charging. You want to see between 13.5 to 14.5 with the truck running (alternator is doing it's job). Off anything right around 12 volts is good, what volts can't tell you are the available amps, but in your situation everything is presumably fine unless it's still stalling... is it?

Looks good. Batteries do fail.

With the new battery in it is not stalling. I assume the battery was so drained that the alternator could barely keep up for the drive home.

Been reading other sites since I posted this and it looks like 12.8V resting is appropriate.

Nobody is gonna comment on the 480+k odometer? Holy cow!

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You changed the battery and cleaned up the connections, so it's a bit hard to tell which was the real culprit. However, the stalling was likely due to intermittent connections, but a bad battery with an intermittent shorted cell can also cause issues like that.

As said, your current observations indicate everything is now working properly.

IKR?? @randy88fj62 That's damn impressive!

Mileage Goals!

Original engine / trans /etc. Still going strong. Dealer maintained until I bought it and now I do all the maintenance.

You want to see 12.6v-12.8v idle with a new battery.
As it ages the resting voltage diminishes. My 10 year old Optima Red started showing 12.0v to 12.1v idle in the last couple months,even after a long drive, little too low for my liking, so I just changed it out last week for an Energizer AGM from Costco. Shows 12.8v idle, 13.5v-14.2v while running.

I just went through with an alternator rebuild, I have voltmeter wired in and it shows 13.8 on start up, 12.8-13.3 while driving and 12.5-12.8 at idle.

Multimeter shows 13.8 directly from battery

Old post, but...480K! I sooo want my runner to go that long.

Well done!

It did take 12 years to do it, haha!