While I was deployed I had this car audio shop install a sound system in my car with a extra battery in the trunk. Since I've come back home(about 2 and a half months) there hasn't been a problem with the car until lately. A few days ago, The battery light will come on at random while driving for a few seconds or more and then turn right back off. The battery gauge on the dash says the voltage is fine and I even took my car to auto zone and had them check and they said both batteries are fine and said the alternator and starter were fine as well. The light went away. now again today while driving the battery light came on and off for a few seconds. I took it to auto zone again and had them recheck it again everything checked out fine. I did the old-school trick to see if my alternator was failing by disconnecting the negative battery terminal while the car was running and nothing happened. The car didn't bog down or anything. In short I've had both batteries checked twice and the the alternator checked and yet the light still flicks on and off every now and then for a few seconds. There's no dimming lights or anything like that so I'm a little lost as to what this could be. I'm thinking it's a short but i just want to get a little direction before I start throwing money at this problem.
yeah that sounds like a short or some type of interference, i would take it back to audio shop and tell them to recheck there wireing ,grounds,hot ,elec they probaly got your battery gauge wire shorting under dash behind radio wireing,just something to check for