just1time

Noticed in the last month or so, some electrical features don't work right unless car is actually on. For example, my power trunk and lock feature sometimes doesn't work when operated at the trunk. And even sometimes when activated from the from the front, it will just pop open and not lift. Yesterday i noticed i Couldn't turn on interior lights if car wasn't on. All these problems go away when i start the car and use them. Which leads me to believe the consumer battery is slowly dying off and only works right when car is on and being charged by alternator.

I will use a voltmeter to check the on and off voltages of the battery when i get home from travel. But does my assumption sound right? Research shows average lifespan of consumer battery is 5years, and my car is a 07MY.
If so, whats the best replacement for the consumer battery, if not OEM. And any particular procedure to follow when replacing it?

Thanks

just1time

DaveW68

That definitely sounds like a discharged consumer battery. I had the same problem....and it turned out that one of the rear vanity mirrors was open and discharging the battery. You might want to check & see if there is something that is discharging the battery when the car is turned off. Also, if you drive the car around for an hour or so, that should be enough to fully recharge that battery. If after confirmation of nothing drawing on the battery when the car is turned off and you get it fully charged....it still loses power, then yes, you need to have the battery replaced. I haven't done any research as to what type of battery is used, but I'm sure that you can pick up a battery at say Autozone or another store that would be a direct replacement without the MB logo on it.

just1time

thnks..good input