Is My Battery Dead ?

You test batteries with the motor off. You test alternators with the motor running.
If a battery has a dead cell it can fry the alternator. The battery should also fail to start the car if you let it sit for a week with out driving it.Go to an advance Auto store. They test batteries and alternators for free. I'd get a second opinion before replacing the battery.

Take it to an auto parts store and they will check it for free. Sort of a second opinion. Then if you need a new one, get it.

There are battery tests you can do (and should do) with the engine off.

An "engine off" voltage reading should be about 12 Volts. (2 Volts each, out of 6 cells). If a single cell is failed (short circuit), you'll read 10 Volts. Perhaps that's what the mechanic saw.

You might expect the car to crank slowly. But, if the engine is otherwise in good condition, it might still start reliably.

Anybody with a cheap voltmeter can run a couple of simple tests. Engine off, 12 Volts, engine on, closer to 14 Volts is a pretty good battery and alternator health check. To test more than that, you need to measure current.

EDIT: Agreeing with K-Y Clay: 12.6 Volts is more like it, open circuit, engine off.

Get a new battery.

"Was my mechanic retarded" - No, that would be you. A battery is not checked with the engine running. Further to that, you asked to have the battery checked a$$hole. So now you don't like the answer and the mechanic is retarded? That's rich.

If your car cranks and starts without any hesitation (like instantly), the battery is good. A battery with a dead cell will have a hard time cranking a car if it will even have the power to crank it. Go to a car parts store and have it checked again if you are in doubt.

Might it be that they wanted to sell you a brand new shiny battery? 'If it ain't broke, don't fix it'.

That's just their way of saying the battery doesn't pass the capacity load tester, your battery is soon to leave you stranded.
It's not supposed to be running, they load tested the battery, not the alternator. SMH, you're like a screen door on a U boat.

Don't buy a new one now. Just wait until you are 40 miles from nowhere and it dies. Then you can pay 3 times the amount you could get one at Walmart or Costco.

If the weather is warm often it will start the engine, but if getting warn out and the weather gets cold, frosty or snow or just plain very cold, batteries do not like that and then will give out if in bad condition.

A dead battery will not start your car. Ask your favorite private mechanic or dealer of your car to do an inexpensive *battery lead test to see what the reserve amperage capacity is. Amperage spins starter motors.
Rhere's not a new, fully charged battery on the face of the earth that tests 13.2 volts. Each cell of a new fully charged battery will test 2.1 volts, 12.6 volts total.

Answer: Apparently not.

First, you don't understand a car battery.
You said:
"it's been a cold winter up until now and I know that puts some wear on your battery overtime."

That is not true.

You also said:
"the car wasn't even on when he tested the battery"

The car SHOULD NOT be on when the battery is tested.

Let's just say that it's highly likely that the person did not tell you the truth.

Just get your oil and filter changed there. Nothing else. If they try to scare you about some other supposed ailment, just say thanks for telling me, and leave. Then have somebody else check it.

Personally, if a repair place lied to me, I'd never go back.

-Engine overhaul mechanic,
-Electrical system expert,
-General automotive mechanic,
since 1971

Valvoline was trying to make an extra buck off of you.

"a DEAD CELL.. meaning my battery is juiced out."
You don't know what a dead cell means. Batteries usually have six cells. One is faulty. Often just topping up with distilled water will fix the battery. Have you EVER checked the levels in your battery? If you haven't the problem is your own fault.

A fully charged battery will read 12.6 volts. There are 6 cells in a 12 volt battery. Each cell provides 2.1 volts. When one cell is dead the battery will read 10.5 volts. A dead cell will drain all the other cells if the battery sits overnight. If the battery is over 3 years old just replace it.

Crappy connection can throw test results off. I prefer removing the terminals and hooking it directly to the posts. Of course with a memory saver installed to the DLC.

Often times if you overfeed a battery it can gorge itself and die.