OK I'm having a little problem. Lastnight it was raining like hell here in L.A and my windows got fogged up. So I turned on my rear defroster and instantly my battery gauge dropped from 14 volts to just below 12 volts. Once I turned it off it went back to 14 volts is this normal or is this a problem?

 

doesn't take much current to activate the rear defrosters, i would imagine you have a short somewhere between here and there. I would pull the paneling on your hatch to see if it is collecting rain or something. Other than i would just check to make sure everything is snug... i'm having problems with my volts hopping around also but mainly related to rolling up/down the windows and kicking on the A/C.

 

Short most likely or the alternator is going south, the battery may be not long for this world, or maybe the electrical system is having issues with all the rain that you are getting.

 

Beg to differ....any power going to a heat producer, whether it be A/C Bathroom Heater or D/C Rear Window Defogger will be a large Amperage Puller/Drain.

None the less, have a load test done on your Alt and Battery