FormulaZR

My father has a 2007 SL550 and recently had both batteries replaced due to age. Everything was fine until Monday when he tried to take it for a drive and the car has absolutely no power. Battery under the hood is showing 11.5+ volts when tested with a multimeter. The terminals don't have any corrosion and nothing has changed since it was parked a week ago working correctly. Any ideas where/what to start checking?

moretech

Are you saying BOTH batts are dead or just the front?? I'd disconnect the rear batt 1st then pull the front and have it checked or charged ( if it will charge) reinstall, front batt 1st, then rear, and see where it goes. Could be a battery failure --premature. Some members caution against jump starting so my idea here is safer way to go. Absolutely need to know if the front battery is good or not. Then worry about anything else later like battery cable is broken, starter gone bad etc;

moretech

Rudeney

These cars have several electronics devices that are always powered, so after sitting for a week, it's not uncommon for the batteries to be low. For this reason, many people who have these "garage queens" will put a trickle charger on the consumer (rear) battery. The C-Tek is the recommended model. Also, check that the PSE pump is not running continuously. Air leaks can cause this and it will quickly drain a battery.

FormulaZR

No, neither battery is dead. Both have 11+ volts.

What I am saying is the car has no power anywhere.

It's "as if" the batteries are disconnected - but they aren't and they both show voltage when tested with a multimeter. Even putting a battery charger on both results in a battery that charges less than 15 minutes before indicating charging is complete (I am using a known good charger). I am unsure if there is a certain module or fuse I should be looking at that would control global power to the car?

Rudeney

11v is too low. A fully charged battery should be 12.6v. But the problem may not be the battery, but a fuse. Check this thread:

https://mbworld.org/forums/sl-class-...-t-charge.html

bobterry99

If that is literally the case, then you must have several blown fuses. Refer to the document Lee uploaded to this post: https://mbworld.org/forums/sl-class-...ml#post3304569.