I did a search on this forum regarding this issue, but maybe I'm just not very good at using the search feature.
With the truck off, battery voltage is 12.25. Last time I drove the truck was about 24 hours ago. I read on a Ford dealer site that a fully charged battery (without the engine running) should be 12.6, and if at 12.4 the battery would be considered only 75% charged. 2019 6.2L with 15K miles. Single battery. Seems to start fine with the exception of exceptionally long starts now and then that I think may be related to the fuel pump. But that's a whole other story. Could be that I need to drive it more often and on longer trips to keep the battery in good shape, but was wondering what other people were experiencing in the real world for their battery voltage.

 

If you are checking the battery voltage with the battery still hooked to the truck, there are a number of parasitic draws on the battery until the truck goes to sleep, so you can't get a stable reading from one time to the next. Also, battery voltage is not the proper way to asses battery health, a load test with a good tester is the only true way to check battery health.

It really sounds to me like you are worrying about nothing.

 

I would find it hard to believe that a 2019 with 15k miles would have a bad fuel pump.

Your battery is OKAY right now, and OEM batteries are hit-or-miss for longevity. I have had some last 7+ years, and others that barely made it 3 years. Basically anything over 12V is okay, but should be replaced soon. 12.4-12.6 is 'good.' Anything under 12V is a bad battery and needs to be replaced.

 

Batteries are not very good overall from the factory in these trucks. Replace with an Odyssey AGM or NorthStar AGM. The long crank is most likely your fuel pump, known issue with them.

 

Thanks all. I checked again and it's now at 12.5. As suggested, I think the truck hadn't shut all the way down when I got 12.25 previously. Having problems with my wife's Mazda battery, so had bad batteries on my mind. For the fuel pump, dealer said it's a known problem, but of course it was fine when they started it. Said bring it back when it has hard starts all the time and they'll replace the pump.

 

put a maintainer on it if you’re worried. They are designed to keep it topped up.

 

In general, a fully charged battery that has been allowed to rest (after being charged) should come in at around 12.8 volts. That's what it would look like if it had been charged outside the truck (no connections/draws). If you can get 12.6 volts with the battery installed, that's about right.

My driver side battery was replaced under warranty due to significant overflow out the top vents. The replacement is doing the same. The passenger side battery is still the original and doing well after 5.5 years.

I put a charger on the truck if it's going to be sitting for more than a week. I use it primarily for towing my RV trailer, so the truck does sit in the garage a lot. I use a CTEK MUS 4.3 connected to the passenger battery.

EDIT: I'm more used to working with AGM batteries like Odyssey, where 12.8 volts is charged. An old school flooded lead acid battery is considered charged at 12.6 volts.