So I have a volt meter that plugs into the cigarette lighter. With nothing on, just the car, it shows 13.8-13.9 volts in the cig lighter. With headlights on, it dropped to around 13.5 give or take a couple tenths. With all electronics on, like AC, air recirculation, fog lights, it'll drop to mid to low 12's on the Cigarette lighter voltage gauge. I checked the voltage on the battery in the same conditions and it shows 13.4 and never dropped. The cigarette lighter with everything on at idle will drop voltage slowly. I ended up seeing like 11.5 volts in the cig lighter after like 10-15minutes of sitting still at idle and same 13.4 from battery. The batteries voltage never drops, stays at a constant 13.4 while voltage from cigarette lighter eventually drops to mid 11's. Never seen it go lower.