Intermittent instrument clusters working. Today battery wont hold a charge.

1999 Plymouth Voyageur. 300k+ km. Last winter the instrument cluster stopped working, started again in the spring. It quit again a month ago. Replaced the cluster with the same result. Yesterday, I left the door open for about ten minutes (interior lights on and engine not running) needed a boost. Today the van stopped running while driving (battery died). Headlights, radio and fan on. Had the van towed home

Battery is about a year old. Tested three times and it is "ok".

Is this a ground issue? Do I need an alternator?

Any thoughts?

Help!

Dave