Battery reading 12.0-12.1Volts?

[bluebombersfan]

I just bought a new battery for my 2012 ford f150 3.7L. When the truck is running I am always getting a healthy 14.5 volts. But other then that when it is not in use the battery will usually read 12.0-12.1 Volts. Isn't this a bit low? Shouldn't a full battery be more like 12.4 Volts?

 

[Mickey Bitsko]

Maybe even a little higher..12.7 at rest, Take it back and let them put a load test on it. AFTER your truck sits for a few minutes DO the test.

 

[RonD]

14.5volts is not healthy, it is REcharging voltage, it should be down below 14volts after a few minutes, 13.6 is average, that keeps battery charged but doesn't "cook it", above 14volts "cooks" the battery.
Then turn on all the lights and heater fan to high, voltage should drop and then come back up to 13.6volts, that means voltage regulator is working and all 3 fields in alternator are good.

Yes, new battery should be 12.7 to 13volts.

Could have a dead cell or bad volt meter

 

[bluebombersfan]

Today I manually charged the battery and got a reading of 12.6 when it was fully charged. Sure enough after a few hours it was back down to 12.1 volts. I will get the battery tested but I am very sure 12.0 or 12.1 volts is not a healthy charge, especially not on a brand new battery. I would assum a short of some sort would get the check engine light on but I am no mechanic.

 

[RonD]

Battery has an internal short most likely.

Unhook battery cables and do the same test, if voltage holds at 12.6v then truck has something on that shouldn't be and it is draining the battery when it sits.

Truck should have a "Battery Saver" relay that will cut all power after 20-30mins, except the clock/radio presets, keyless entry and alarm(if so equipped)
That will prevent a truck "short" from draining the battery

 

[xcross]

Could just be a simple grounding issue that is why you are getting a false reading in your volt meter.

 

[Mickey Bitsko]

Sheesh... go get it tested already

 

[adsm08]

Your truck may also be equipped with a battery monitor system that needs reset with a scan tool when the battery is changed. I can't remember what year they started the F-150s on that because if got phased in over about 3 years with different vehicles getting it at different times.

 

[kimcrwbr1]

Are you testing thew battery disconnected from the truck? Pull the battery out and fully charge it and measure the voltage should be around 12.7v then let it sit overnight and check it again if the voltage drops go get another battery. Not the first time one was bad new. At around 2500 rpms with nothing on the charging voltage should not be more than 2.5 volts over battery voltage or over 15.3v. At high idle speed with the lights and heater on you want to see no less than .5 volts over battery voltage or less than 13.3v at 1200 rpms.

 

[xcross]

By my guess its a weak battery that need replacement. Drain overnight is not normal it could be leaking or worn battery plates.