battery loses charge quickly

[Route 66]

My battery on my 02 is losing its charge quickly after leaving the parking lights on for less than a half hour. I had a new Interstate battery installed at the end of June of this year. Is it the battery or is the Alternator? Could this be the ignition switch? Who can help? The car has 57,000 miles.

[Showtime22]

Sounds like it could be the alternator if the battery is newer.

[Zurawek]

seems a little early to be battery but if it was the alternator it wouldnt start back up. go to autozone and get it tested for free. then get an optima battery FTW

[Aindriu]

Don't know if this helps much but my battery drain was coming from the blower resistor. So if your A/C is playing up a bit, too, then that could be the case.

[Route 66]

I put the battery charger on and set it for 10 amps. I let it completley go to a full charge and then with charger still hooked up I turned on the running lights and as soon as I did that the charger went to the level where the red and the green are represented on the charger. Battery?

[Aindriu]

If you get another battery get a Bosch S5. Top notch batteries they are.

[Edwin NL]

what is the voltage output when idling?