Is it true that if you leave the ignition in your car running with the A/C, you'll run down the battery?

%26amp; what's the worst that can happen to your car for doing that? I usually let the air run for a good 15 minutes if it's burning hot for 15 minutes. In New Orleans, the heat is so hot you can't even touch the steering wheel. %26amp; one time I did that, %26amp; my former foster brother-in-law told me I'd run my battery down. But can't the battery get recharged? %26amp; also, how much would a new battery cost for a new car? My car was sort of new @ that time, but I don't have a car now because it got repossessed. I was just wondering if what he said was true because I asked someone else, %26amp; the other person said he was lying. I want to know so that in the future if I get another car, I'll know what I should do.

Is it true that if you leave the ignition in your car running with the A/C, you'll run down the battery?
if your car is started and you have the a/c on your battery will not die. when your car is running its not really getting the power from the battery, it comes from the alernator. if your battery does go dead you should purchase a new one. the best is an optima battery. they are dry cell so they dont have water to leak out of them, also if you do end up running the radio or leave your head lights on over night it keeps enough amps in it to start your car. the down side is these are $150
Reply:These people are all full of it. A good 80 amp hour battery would run the fan for over 8 hours without dieing even if the engine isn't running. If the engine is running you won't ever run it down. The compressor doesn't use electricity and the fan doesn't use much. As long as you don't have headlights on or something, the alternator at idle is more than enough to keep everything going.
Reply:if the car is on with the engine running no because the crankshaft rotates the alternator generating electricity and sending the elctricity bak through a wire but if the fuse is blown then it wont recharge


ifd it is on battery iin the on position with the engine off and the ac running yes it will drain the battery
Reply:I think your asking if you leave the key in the on position before starting the vehicle will it run the battery down. Yes, the fan is running off the battery power. Without the engine running, the a/c won't be doing anything but fan will still operate. At some point the battery will die.





If you are asking about letting the engine run with the a/c on, this will not run the battery down. Because with the engine running the alternator is continually recharging the battery. There is no reason to let it set for 15 min. though. You don't need to cool the whole interior off just hold on to the steering wheel. Just rub it with a wet rag or something. Or hold it with a towel for a minute. That's a waste of fuel.
Reply:Yes!! It'll run the battery down.





But if you drive the car for awhile, say 40 minutes, the battery should recharge.





The battery will only stop working when it is very old.
Reply:At idle speed, the electrical draw from the blower fan and the clutch to engage the compressor will probably be greater than what the alternator is putting out, so yes, it will drain the battery. That being said, if your battery is in good shape it should be fine for 15 minutes as long as you're going to drive it for a while afterwards, so that the battery can recharge what it lost in that time. At normal driving speeds, the alternator puts out more than you'll use, so the battery will recharge.





So - don't run the AC idling for 15 minutes if you're only going to drive it for 5 or 10, if so you will eventually kill the battery, and that is whether it's new or not.





As for battery prices, I'd check with Pep Boys or Wal Mart, they're about the cheapest I've seen. Should be somewhere between 50 and 100 bucks, depending on how big it needs to be and how long a warranty you get.
Reply:yeah if you leave it on for a long time.
Reply:Yes it will missy! and with hotter weather, the batteries life is shorter. A battery can run you from $45 and up.
Reply:Well its impossible to run down your battery when the cars running the battery is only used to start the car when the cars running you can take the battery out till you shut it off. The alternator acts as a generator to keep your battery and other systems charged and running while the motor is running. If the if motor is not running then yes you could drain the battery over time but it would take 12 hours to do that.
Reply:I used to leave my car on so that only the radio stayed on and I ran down the battery. Getting a new car battery is not cheap.