It’s not, but the OP asked about full charge. The condition is just an estimate.Voltage test is not sufficient to determine the health of the battery.
You need to do Load test.
The voice of reason!Better question: What events led up to you asking?
Around 12.6V will tell you that no cells are shorted out. It won't tell you the reserve or peak current capacity of any of those cells.
With a battery that was ideally maintained and just time to retire due to irreversible plate degradation resulting in too low a current capacity, you will still see around 12.6V charged, but that voltage will drop too low under load. I assume automotive starting battery, but it applies to any application, when the battery is no longer suited for it's requirements.
Just turn the headlights on for a minute to get rid of the surface charge.You can only assess state of charge by voltage measurement under the correct conditions. The battery must be rested i.e not recently taken off charge or the engine run. otherwise you get a false high reading, mine reads over 13 volts just after being taken off charge. I prefer to wait a minimum 4 hours or overnight when it will then read the correct 12.7 volts. Secondly the battery should be under no load and ideally open circuit. That's perhaps unrealistic but at the very least modern cars need to be asleep. I only have to open a door and the stupid thing wakes up all the computers and draws anything up to 8 amps which will give a false low reading until it goes back to sleep again which may take 10 mins. All the caveats about voltage measurement not indicating battery health are true but on modern sealed batteries there is no way of determining state of charge other than voltage measurement.
Battery needs to be load tested not voltage tested.Hi Guys.
Thank you all for taking time to help.
My Jeep is having some issues, so i had it connected to a scan tool. I noticed the tool was only registering the Battery at 11.9v at the top of the screen. Now the engine seemed to be cranking ok that morning. With engine running the display says 14.6v. I was unsure what a healthy 12v battery should be reading. Google suggested 12.6v, which thanks to you guys seems correct.
Anyway, as the Battery is at least six years old i have changed it. I got an Excide Platinum, 100ah and 900cca.
Mine is lower than 11.8 (sometimes 11.2 on really cold mornings) and starts the car (a V6) just fine.The battery in my 1995 Miata reads around 11.8 volts every morning, and has for the last 5 years. Always starts the car fine. Charging voltage is around 14 volts. It's an AGM. I think there is something wrong with it, but it has been soldiering along and doing it's job for a long time.
What group size battery do you have in there? I had seen some with group 51 and some with group 35. It is a small engine so it is very easy to start. Had it been a larger engine like a 2.5 or something over 3.5, then you may be in trouble. The Miata is a perfect candidate for those lithium jump pack.The battery in my 1995 Miata reads around 11.8 volts every morning, and has for the last 5 years. Always starts the car fine. Charging voltage is around 14 volts. It's an AGM. I think there is something wrong with it, but it has been soldiering along and doing it's job for a long time.
Hi.100ah is fabulously large for a gas passenger vehicle. Sounds like a nice battery. H8 sized?