95 tb 3.8 charging/battery issue

[mudrunner80]

Most of my tools are 300+ miles away. I started my car fine. Drove less than a mile. Stopped at my sons school for 15 minutes, went to start it and even dash lights were weak. No start.
Boosted it started quick. I let it idle 15-20 minutes and noticed the tach kept jumping up every 15 seconds or so. I decided to drive it but dash lights kept. Tripping off then instantly back on. Almost like a loose connection but everything seemed tight.
When I went for a spin its like a serious drain on the battery. Headlights flickered and it skipped. Since it started fine one minute then completely dead shortly after dead battery but if it was just the battery would it make it skip or want to stall when I tried to put the window down (power windows) with head lights on and wipers. I know its vuage with this description but any help or guidence would save me a fortune

[97Bird]

If there is an Autozone or someplace like it nearby, I would have them check the charging system for free! Sounds like an alternator has died. Make sure all the connections to the battery, alternator and grounds are clean and tight.