Volvo Repair: Volvo V90 Battery Draining, volvo v90, digital multimeter

Question
My 1998 Volvo V90's battery keeps draining.  Today is the third time it has happened.  Up till now, my solution has been to take the battery to O'Reilly's and have them recharge it.  Every time I have gone they have found the battery to be entirely depleted of charge.  O'Reilly's ran an electrical system check after they recharged the battery.  The alternator and starter both check out fine.

I have read on this forum and elsewhere on the Internet to do some electrical testing of the battery when the car is idle.  I have a Radio Shack 22-Range Pocket Digital Multimeter  (url: http://www.radioshack.com/sm-buy-the-22-range-pocket-digital-multimeter-on-wwwra...).  Will this work for testing?  Do I just touch the positive and negative battery leads with the tester and it will give me a current.  Then I will have a friend pull the individual fuse out one by one and check for any current changes.

The left front turn signal cover was ripped off a couple months ago.  I have not replaced it yet.  The light bulb is exposed to the elements.  I have ordered an entirely new turn signal assembly.  Could moisture getting in around the bulb cause these battery drains.  I noticed that during wet weather the battery seems to die.

The car has a faulty radiator temperature gauge per a system check performed by AutoZone.  Could this be causing battery drain?

Answer
Michael, lots of things can cause battery drains. Most common ones are aftermarket radios and CD players being installed incorrectly. On the V90, the dome light assembly is a possible culprit.   Any multimeter will check for voltage, etc but the true test is to use a test light, disconnect the positive battery terminal and take it off the battery then clamp the test light on the terminal and then place the tester end on the positive side of the battery.  IF the light lights up, then there is a draw.  If its bright, then there is a serious draw.  What is supposed to happen is you touch the battery with the test light, the light shines, then goes off. That means system is okay.  If it does the opposite and shines all the time, then there is a problem somewhere.  If this is not clear to you, let me know and we can go further.  Roger