it is the cop in me that suspects the secondary battery back up isn't mentioned, because car thieves would have the knowledge then to steal our cars...when engauging the tow switch, which deactivates the alarm, does it also deactivate the ability to start the car? Just a thought. And, I would think the skreem module would contain the capacity to sound the alarm. I have never seen a small battery exposed anywhere, and I have looked at a few totalled cars at the junk yard while searching for parts. Granted the drive tranes were gone, but I would think this backup would be well hidden in the dash area...just my .02