trabots

My 2006 SL55 after sitting for a few days the remote doesn't work and convenience functions are not available temporarily. Both batteries have been checked out as OK and show high 12 to low 13 volts before starting up. After a short drive everything starts working again. Interestingly, while idling the main battery shows 14.3 volts while the small battery shows 15.4 volts. I don't understand why that is and is that why I am having issues? Cheers.

cdk4219

These cars are notorious for parasitic draw. Things just don’t shut off when the car is shut off. Everything from alarm sirens to vacuum system leaks that keep the vacuum pump running.
Most people put a smart trickle charger on the back battery and live with it. Electrical nightmares when these problems start.