Dead Battery Sometimes

Hey, 1998 astro mark III , I've had 5 days, had dead battery in the morning 2 days, been cold outside, jump starts right away, then runs fine all day, battery dated 1-06, alternator looks off the shelf new, gauge inside on the pos side, expect one time when running everything, went way towards neg, stopped that and now always pos, switch battery? have mechanic test charging system?

Start with the simple things.... Make sure the cables are tight.

I had the same thing after switching batteries in my 95. Turned out I just hadn't tightened the cable bolts enough...

i agree, check that the cable connections at the battery are tight and clean. also check the engine ground wire. bad grounds are often over looked. then pop the caps and check the water level in the battery visualy, no maintenace batteries ain't so, they still vent to atmosphere just at a higher pressure. or better yet check the battery water with a hydrometer to see if the specific gravity of the acid solution is below the freezing point for your area.

Like CD said, start with the simple stuff. If that's not it, you'll have to dig a little deeper. Parasitic draw, if above 1200ma, (1.2 amps) can kill a battery overnight. Mark III is an aftermarket conversion that has several add on electrical accessories. Test for draw on the battery, if it is excessive, locate and repair the cause. An ammeter would be first choice however, a 12 volt test light connected in series with the positive battery cable will also work. Make sure all doors, lights, accessories, and the ignition key are off. Full brightness would indicate something is drawing the battery down. There is a fuse panel on the driver side wall just behind the driver seat. All fuses in that box are for accessories that the converter added. I would start looking there.