Chrysler Repair: 00 T & C wont start or shuts down a few minutes after being started

Question
A couple of weeks ago I started having trouble with the van starting
Sometimes it wouldn't do nothing at all or just click.the battery light came on a week ago, so I changed the belt tensioner with a new one, because that's what i did  4-5 months ago when I had trouble keeping the battery charge, change the tensioner, but the battery light came on again. Had the starter check(it was bad), put a new one on, car started up no problem, but battery light came back on, then the next day car started but shut down after a few minutes. Had battery checked(was bad, when I was told a week ago it was good. Put another battery in, and still the same thing, van starts but shut down after a few minutes. I seen on some websites it may have something to do with the alarm system, but this 1 doesn't have one just keyless entry. Your help/answer would be greatly appreciated. Thanks Cornelius dixon

Answer
Hi Cornelius,
The alarm system shutting down the engine occurs within 2 seconds after starting, not minutes, so that is not the reason.
I would focus on the alternator/charging system particularly if the battery light is 'on' when the engine is running. The other possibility is that there is something that is draining the battery overnight which shouldn't be drawing current. You would need a volt-ohm-milliamp meter to check that possibility by putting between the - post clamp of the battery and the - post proper (after removing the clamp from the battery to see what the ignition off draw is. After a few minutes from turning off the system the off draw should be less than 50 milliamps.
With that same meter yous should find that the voltage across the battery posts with the engine running should be over 14V, and if not then the alternator is likely bad.
You could also check for engine fault codes using the ignition key: "on-off-on-off-on and leave on" doing that in 5 seconds or less elapaed time. Then watch the odometer window to see if the mileage reading is replaced by a 4-digit number preceded by a P. Let me know.
Please read the PS (below) and respond to it.
Thanks,
Roland