dazzleaj

2002 Astro, 103,000 miles, new fuel pump (the good one), key stuck in the ignition for over 6 months (just put a ball cap over it and lock doors) runs great.
Went on a 10 day trip, hurricane came through while we were gone, rained hard for days, van pointed slightly down hill. Came back to a completely drained battery (9 months old). OK, I assumed that water came down the crack in the hood right on the battery and for days just shorted it out. A bit far fetched but plausible. The van was tilted down enough that all the water that hit the roof would have cascaded down to the hood. The battery is situated so the flood would have hit it right between the terminals. Possible.
Trickle charged the battery for 5 hours to get it live again and then charged it. Van started and ran as always. Two weeks of intermittent use, no problem.

Saturday, took it out, no problem. Yesterday, Monday, went to start it, Deader than doornail, completely drained again and this time no rain.

I searched the forum and found a couple occurrences of this but no answers (one rocket scientist suggested "you might have a dead battery").

I am looking for any credible info before I start the laborious process of searching for that king of gremlins the, Intermittent Short. Guessing is tolerated but actual experience with this problem is greatly appreciated!

kevinkpk

Well, if it keeps it up, I'd suggest after stopping for the day, pull fuse on radio as it does draw (supposed to be) small amount when off to keep the clock, and presets. I had an 08 with an internittent issue like that (dealer said it was the radio, new radio didn't fix it). I'd also suggest check the cells with a hydrometer. Pulling the fuse everytime is a PITA, but that, other being able to check the current draw when off is about the only thing I know.

T.Neff

After charging the battery,you should measure 12.4 or more volts.Checking the charging system you should measure at the battery while running 14.4 or more volts.Take it to a local parts store and have them load test the battery.

If you don't find anything there a circuit check is as follows:Take off the neg cable off the battery.Run a test light between that cable and a ground.If with the key off you have the test light on,you have a short.Your interrupting the circuit of the battery and it is find a ground(the short) somewhere else.Go to the fuse box and pull one fuse at a time until the test light goes out.It is that circuit that you now narrowed down the short to look at closely.

These Astro's have a poor grounding wiring harness.If you where to trace the ground cable,you would see it leads to just a little stud in the rad support.So if all else has checked good above,there is what is called the big three upgrade.You would need either two types of battery connections.One is a battery with side post and top post connections or battery connections that convert to a two post connection.

So given that what is the big three??. Still using the O.E.M. harness you need the following:

About 6' of 0/1 cable and three d ring ends.Basically that is welders cable.Solder one d ring to one end and cut it to be long enough to run between the neg top post of the battery to a ground clean chassis ground.Then solder the other d rings on the cable to run between the engine ground and the chassis.Make sure those are clean contact points.Now that is two of the big three upgrade.

The third is about 6' of number 2 wire.Run that between the Alt output with the third soldered d ring and the top + battery connection.

For the two top battery connections your going to need new top style connectors.

Right out of the box,your going to see because of the upgraded cable size all the lights are brighter and everything else seems to have gained more powerful.

Lastly.If you recently installed a stereo system or remote starter system that might not have been put in correctly,that could be a cause of drawing the battery to dead.

dazzleaj

Thanks for the tips. Yes I did test battery and alternator voltage, both were correct after the recharge and the next day (even a sick battery can show 12.4v right after charging).

I like the idea of rewiring a charging/ground/starting system. I ran a second set of wires on a 1986 ford van with a 351w and completely changed its electrical personality. I hadn't occurred to do it on a newer vehicle. I also have routinely put solenoids in the lighting circuit of most of my cars and trucks to take the load directly to the battery, gives brighter lights and reduces the chance of loosing lights due to a burnt up switch or old wire connection.

I like the idea of the test light between Neg and wire, after the rain stops in a few days I will try that.