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Discussion Starter · #1 ·
I know it's nothing new on these trucks, but my '04 Sierra ECSB with 120k miles has been having battery drain issues on and off for the past few months. Before I go any further, I should mention that the battery was replaced fall of '13 with a high-end Bosch 900 cca battery. Anyway, I started having issues at the end of last summer. I'll list the issues and what I did to troubleshoot them in chronological order:

1. Summer '14: Battery was completely drained after sitting in the LAX long-term parking lot for 17 days. Nothing was plugged into the cigarette lighters and the stereo (aftermarket JVC) wouldn't power up after being jumped. The stupid Metra warning chime box was found to be the culprit, and had caused several issues in the past. I replaced the box with a different brand, which seemed to have fixed the issue.

2. December '14: Truck sat for five days and the battery went completely dead. I jumped it and it started right up. The next day I used a multimeter set to ammeter in series with the negative battery post to see if there was a parasitic draw. It consistently read 250 ma. I was scratching my head for the better part of an hour until my roommate (who routinely drives my truck) came out and casually mentioned that he leaves the SAT radio receiver turned on overnight. Sure enough, when he turned it on, the reading jumped to almost 1 amp. Mystery (or so I thought) solved.

3. Present day: After getting steadily worse and worse, it is now to the point that if the truck sits overnight it has a hard time starting. I had a 12v power strip with three cell phone chargers and a GPS plugged into one of the power ports which I now keep unplugged when not using the truck, but the battery still drains.

Some things to note:
-The voltmeter never goes above 13.5v even when charging right after the truck has been jump started. It used to hover between 13-14.5v but not anymore.
-The battery terminals are clean and the belts/tensioners were replaced fall '13
-I recently checked (again) and there is no parasitic draw (at least while I am testing it). With the key off, even after sitting for ten minutes, it's still only drawing a steady 250 ma.
-The problem is steadily getting worse, to the point that I've left my jumper box in there just in case.

To me this sounds like an alternator issue, but if it turns out to be the battery I think it's still under warranty.

I'm going to go to VatoZone this weekend to get my battery/alt checked, but I thought I might bounce it off some of the sages on here and see if anyone else has any good ideas.
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