Charging problem in 87 legend?

Hello all,
Looking for some feedback regarding a recent incident with my 87 legend.
Having been left idling with the stereo running, and the headlights on for
approximately 45 minutes in approx -10 Celcius weather, the headlights seemed dim from the outside as I approached, and when I got in, the interior lights would not work. When I put the vehicle (Automatic Tranny) into reverse the engine sputtered, and then to my surprise died. To my embarassment this happened while I was shopping for a new car, but fortunately the dealer offered a boost which caused the motor to start promptly and purr like a kitten again. On the drive home everything seemed to be working as normal. When I got home, I shut the car off, waited a few moments, and attempted to restart the car. It started NO PROBLEM. I did notice however that the Idle is a little slower than I thought it should be (according to the tach it seems to be about 500-700 ish RPM, needle about half way up to the 1). Please correct me if I'm wrong, but I thought these things needed to idle about 800 RPM??
SO, I'm wondering if the seemingly low idle could be creating insufficient charge to maintain the battery while idling??? Other thoughts are toasted alternator, toasted battery, or something of that nature.... Any input, thoughts or advide would be appreciated if it can help prevent this occurance in the future.
Thanks in advance. (sorry 'bout the longish post....) Noland
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wrote:

With headlights (or DRLs) on, and a battery that's how old?

Don't leave it idling for long periods with the headlights on in cold weather unless you're sure of your battery.
The days of ammeters in cars are long past, which is a pity, because an ammeter would have shown you right away that your headlights couldn't find enough current coming from your alternator and were sipping from the battery. Maybe your idle is a little low, maybe your alternator belt was slipping a bit. Was the heater on too?
I think you were just asking too much of the system.
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