Chrysler Repair: 99 300 M unreliable start, resistance one, volt ohmmeter

Question
Not sure weither its the alternator charging the battery or the battery not holding a charge, but some mornings i will try to start my car and the starter will just click and my trunk will pop open. Or my battery will just die and when it does my trunk will pop open. If i drive it around for awhile then it will b fine to start later on depending on how long i let it sit. I had it in the body shop and it had been doing this everyday after i got the car back. I took the car back and got them to check for any shorts that could have been occuring but there were none. I charge it on a battery charger and it holds the charge, enough that it will start after i unhook the cables. I'll use my car throughout the day and park it around 5pm and then the next morning sometimes it will still start. but other mornings i look at my clock and it shows that it dies 4 am or even as late as 8 am. ive checked trunk lights, glove box, hood, etc. nothing stays on only the clock until the battery completely dies. Any suggestions would b appreciated. Thanks

Answer
Hi Josh,
Chances are that one of the interior lights is on all the time (glove box, under the hood, in the trunk). So look carefully to see whether those bulbs are truly going off when the door is closed.
The other approach is to use an ohmmeter to measure the resistance that each of the fuses is supplying current to.
If you can get a hold of a volt-ohmmeter with a digital readout you could differentiate a too low but finite resistance from moderate acceptable resistance. One of the fuses is supplying power to a circuit with a too low resistance and that is why the battery is running down. Begin with the fuses under the hood in the power distribution center box near the battery. One pin socket of each fuse is the hot side which has 12V on it from the battery, so don't touch that one with the meter in the ohmmeter position, just use the voltmeter to find the "cold" pin after removing each fuse. The 'cold' pin is the one to measure for resistance(i.e. all the lamps and devices are attached to that one). If you set the meter to read ohms (200 ohm full scale) and touch the - lead  of the meter to any shiny metal body surface and the + lead to the cold pin of the fuse socket it should read more than 50 ohm, the more the better. Make sure all the doors are closed when you are doing the measurements.
Then the question is how to find which of the many items on a given fuse that is suspect is causing such a low reading.
So first go thru the power distribution box under the hood to find a fuse whose cold side reads less that 50 ohm, and let me know which one(s) it is (its label by number and/or purpose). That fuse will supply several fuses in the fuse box under the dash, so we will do the same testing on those fuses once we identity the 'master' fuse which is carrying too much current.
Then we can go on from there to isolate what component on that secondary fuse is drawing the current and check it out.
Roland