This thing will come on while driving down the road, but when I come to a stop it goes off. Might come back on, might not. The battery is about 3 years old and so is the alternator. I can't remember the exact voltages, but with the car off it showed around 12.3 ish volts and with it idling it was around 14.9 or so. That seems high, but I dunno. I did not check what it was at around 2k RPM.