Mystery Battery Discharge

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So I get in the H2 this morning and notice the interior lights are dim, uh oh! As expected, it wouldn't turn over. I got it started with the quick start mode on my AC charger no problem.

I used it yesderday, so it hasn't been sitting. Nothing was left on or open which would obviously cause a rundown. I assume that there's rundown protection on the exterior and interior lights as these always seem to go off and you can leave the doors open without causing a problem.

I do have some ideas for potential culprits:

1. Last week, I applied the "DRLs on with Parking Lights" mod using a diode so the parking lights will trigger the DRLs and not viceversa. This was first choice as the culprit since I just made the mod last week. It seemed very unlikely that this was the cause. I'm not real wise on electrical though, so I'm not sure if an unintended discharge situation could result from doing this wrong. The jumper is well made with the diode shrink wrapped and wire only exposed in the relay slots .

And I don't think one of the relays was stuck open...there was no light coming from the DRLs or parking lights that I could see. But I suppose it could have been faint.

2. I have a portable DVD player that's always plugged into one of the console power jacks (been that way for ~8 months). These jacks are always on, but we always turn the DVD off when it's not in use. It does use a tiny bit of power to drive the IR receiver for the remote control, but I assumed this tiny draw wasn't enough to cause a problem as long as we drove daily. Could I be wrong, could this constant draw has weakened the batter so it can no longer hold a cranking charge overnight?

3. My alternator started whining in the past month. When the H2's running, the charge indicates 14V. So I assumed that the alternator's functioning okay and I haven't rushed it in to get looked at. But could the regulator have gone bad in a way that wouldn't prevent good charging, but would allow parsitic draws when the vehicle's off?

4. Perhaps the battery's just getting old and tired and needs to be replaced.


Any other ideas for things I can check before dragging it up the Twin Cities for a dealer checkup? I have a multimeter, but for low current applications. Is there any use I can make of this in searching for a drain?

In the meantime, I undid the jumper mod in the fusebox, but left the DVD plugged in the way it's been for the past 8 months. If the battery goes dead again, I'll unplug this and see if the situation improves (Change one thing at a time until we find the issue). Plus I'll keep a spare battery in the back, just in case.

Man it'd be nice to have that wrangler dual battery setup.