If a car's battery (fairly new, probably about 2 years) is completely drained, and I mean totally and completely, is it possible that it is just dead from here on and even after charges it wouldn't be able to hold that charge?

My mom left the car running and forgot about it for about 4 to 5 hours. Came back and the car was dead. Charged it and she drove it for about 45 minutes and came back. After a while, she tried to leave again and the FOB wasn't recognized and after several tries, the car just died again.

I'm guessing it's just dead and no longer can hold a charge, anyone else think anything different?

 

You might be right.

About a week after I accidently drained my OEM car battery in my car, it took a dump on itself. Dealer offered to replace it if I paid a certain percent. I said no and bought an Optima... no problems since.

 

It's a pretty good bet that the battery is toast. Car batteries are not meant to be fully discharged like that, they usually get damaged. If the voltage measured is below 9.6, one or more cells may be dead.

If you want to be certain, take the battery in to Kragen and have them charge and test it. The charger will charge the battery in an hour (assuming it will take a charge) and then it will do a load test at the end. If it's bad, it will fail the load test. Some batteries will not take a charge at all and after five minutes on the charger, the machine will indicate that it's bad.

 

You guys might be right. I don't have a Kragen near me but I will be taking it to Costco tomorrow to do the Charge Test or just replace the battery.

Thanks.

Are there any places that gives money for dead batteries?

 

I can't say it is impossible, but I can say that i have drained several batteries (between new and several years old) and had no problems after jump starting and driving for a few miles.

 

Oh, and just curious, why did the car stop running? If a fairly modern car, even at idle, the alternator should put out more energy than is used from the battery, so the battery shouldn't have run down. Did the car run out of gas? If not, I'd wonder if there is a problem with the charging system, which could explain why everything didn't resolve after she drove it a bit.

 

Many cars will run odd/badly when the battery is not holding a charge. The battery is part of the circuit and if it's not putting out what it's supposed to, the components expecting a certain amount of power start to malfunction.

 

But we were speculating on whether the battery being discharged could have effectively killed it. I'm looking for a cause for it to have become discharged in the first place.

Also, I'm curious, I've heard what you said before, but have never understood it. A car battery generally puts out around 11.5 volts, and an alternator around 14.4 volts. How do any of the electronic components "know" that the battery is missing from the circuit since it doesn't add to the available voltage?

 

A fully charged battery should read 12.6 volts, 2.1 volts per cell. The components don't know how much voltage, but the computer does. It's set to expect a certain amount of voltage from the electrical system. When it doesn't receive enough, it runs bad. Think of it like a failing fuel pump or clogged fuel filter. You don't get enough fuel to the engine so it runs bad because it's not receiving the amount of fuel needed to run efficiently.

As for the battery, sometimes they just go bad. I've seen batteries bad off the shelf or they can go bad even just a couple weeks/months after purchase. It's not common but it does happen.

 

all lead acid batteries are designed to be taken down to 20% deoth of discharge, anything more than that will do some form of damage to the battery. The amount of damage depends on the batteries condition before being fully discharged.

However, if your mom forgot and left the car running and came back to find it dead, I would suspect that your alternator may have died

 

 

Yeah, that's the strange part of this... if the car is running, the battery should be charged... unless the alt died. Maybe he meant she left the radio on with the car off

 

Guess you've never bought a battery before, eh ?

You'll need the old battery to get back your core charge... They typically charge 5-10 bucks that you get back when you bring in the old battery. They recycle them.

 

Draining the battery will decrease the life of the battery, but I've never had one die (unless it was really old) just by draining it... I've just jumped the car without an issue... Battery charges, but it's not as strong as it used to be.

If the battery is older than 5-6 years old, then completely draining it would probably kill it.

 

FYI The battery on my explorer died this past summer because it sat for 6 months with a dead engine. The battery wouldn't power anything in the vehicle. Once the new engine was in and the battery charged it has been fine for the last 8 months

 

Dead batteries suck. I just went through that with mine. If I even listened to the radio for a few minutes with the car off, the battery would die and I would be unable to start the car. I bought a new one right away.

 

Yup, the alternator died. The technician just told us.

The battery is fine though for those who are wondering haha.

Thanks.