I did some battery testing on my 92 F-150 this weekend and have a concern. Many publications have said that 12.7 is considered to be a full charge.

So here is what I did.
Check battery voltage - 12.6v
Start engine, check battery with NO load - 14.2v
Start engine, check battery WITH load - 13.7v
Turn off engine and check battery voltage - 12.8v

So it seems ok except for the 12.8v. Should I be concerned? Is this normal for a battery to charge above 12.7v?

 

Yes, it may after being fully charged be at 13.x vdc and go down slowly to 12.6. Its important to see what voltage is a few hours later, if it will hold at 12.6. Never worried if it was a tenth or so higher. Different lead mixtures may cause slightly diff results.

 

You're reading way too much into it - 12.7 is just a vague guide; not an absolute limit. None of those numbers indicates a problem, except MAYBE 13.7, depending on exactly how you loaded the battery. The captions in the photo album linked to this thumbnail image explain most of what you need to know about your truck's battery:


(phone app link)

Is there some problem with the truck that prompted you to test the battery? If so, tell us about THAT, and we might be able to save you some time. It would also help us help you if we could see ALL the truck's details in your signature under each of your posts. Click this & read the caption:


(phone app link)

 

I agree with Steve83.
Just clean the battery terminals and their clamps and call it a day.

 

None of this info is right. You can easily have a good float voltage while the battery will deliver very few amps. The running voltage is coming from the alternator and really has nothing to do with the battery. Not sure what you mean by load/no load. A stereo system? Headlights? You guys are all confused. Take your truck to autozone and have them throw a tester on it. Conductance testing is extremely accurate and will give you state of charge and CCA capacity left in the battery.

 

Depends on the battery design. But, if you have a digital voltmeter that is 100% accurate, please tell me the brand. I have 5 of them, and they never all read the same.

LOL.

This quote above is closest to correct, recommending an Auto Zone load test. Resting voltage is the minimal measure of the state of the battery capacity.

Amperage delivery is what counts.

 

Fully charged or not - doesn't matter if you can't crank out some amperage. I can take 8 D cell batteries and give you 12.7 volts. I 100% guarantee they will never start you truck. Acid levels, plate corrosion, lead-sulfate crystals, they all effect battery capacity but with enough of a "charge" they can read good voltages. Voltage means almost exactly j a c k s h i t.

 

Perfect...

 

True.
A battery on its last legs can have 12.6 volts at its terminals with engine off but not able to deliver its rated amperage.
You're right, an auto battery tester (which tests under load) is the best way to determine if a battery is healthy.

However, the OPer didn't mention any issues which is the reason some here including myself said the OPer is good to go.

 

What you said above is exactly what I'm saying. But you told OP his battery is in GREAT shape and that's simply impossible to tell from a voltage reading. So OP takes your comments and heads into the mountains on an extended trip and his battery goes to squat. Thanks for the help!

The ONLY way to PROPERLY test a battery is under load or with a conductance tester. These tests can be performed for free at any auto shop. Or If OP wants to experiment with his new tester get a load bank and stopwatch and start discharging the battery while measuring the voltage. You can google all kinds of ways to do this.