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I sometimes will stay in the car for extended periods with music player, parking lights turned on and engine turned off. I was wondering how long can the car battery survive this load. Should I be worried about this?

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up vote 1 down vote accepted

I have a heavy duty truck battery in my car, and I can run a 640 Watt stereo system all day and all night, with the interior lights on without having any problems starting the car.

But once I accidentally left the lights on for two weeks while on holiday, and the battery was flat.

Those two datum points give an idea of the expected life (the truck batter is about twice the rated capacity of the normal car ones - which is why I bought it)

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Thanks for your answer – Gowtham Mar 16 '12 at 13:54

The question can only be answered if you determine the load that is being put on the batteryand the load capacity of the battery.I have run the radio in my truck for two hours and it started without a problem.I have seen a luxury car with 12 or 14 interior lights run a battery down in 90 minutes from a door left open.Most original equipment radios draw very little current so that isn't much of an issue.What can be of concern is if you repeatedly drain the battery with powerful stereos,lights,powerwindows etc. then recharge it by running the engine. it will shorten the batterys' life along with the alternators'.That being said if the alternative is to idle the engine adding wear to the engine, batteries are cheaper than engine overhauls.If what you are doing is sitting for 10 or 15 minutes listening to the radio it really should not be a concern.

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Thanks for your answer – Gowtham Mar 16 '12 at 13:56

I know every vehicle is a little different, but there's a drive in movie theater close by to where I live. Most vehicles there have no problems leaving the stereo on for 2 hours and then starting the vehicle.

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