Bklyn

Hi all:

I have an S550 4Matic with 125,000 own the clock.

I think the the batteries are original.

Anything I need to know about these batteries?

Do I get electronic warning of any kind when I need to change them?

Any advice greatly appreciated as I am concerned about the car starting on cold Boston winters. (I am concerned about me starting on those cold winter morning as well. Why do I live here)?

EasyPhil

What year is the car? What's the date on the batteries?

Polar Bear

Well, if it is a 2007-2009, it will have a large consumer lead acid battery behind the rear seat that is difficult to access. It will have a much smaller battery under the hood on the passenger side that is only used for starting the engine.

This is a nice setup since if you run down your consumer battery using accessories while the car is parked, it starts with no problem. The downside is that the consumer battery can be almost useless and you will never know as the alternator will pick up. One sign is when you get in the vehicle, observe the interior lighting. If it goes out quickly (30 seconds or so) the rear battery is likely needing of replacement.