wrxin17

So i let my car sit for about 2-3 weeks.... wont start and its completely dead. I jump it with my jump box and the car fires right up but the battery protection comes on the dash and the a/c only works half way. I heard for some reason our cars have two battery's is this true? I currently have the battery that is in the trunk on a slow 2 amp charge. Anything else I should be worried about? I should prob just get a new battery...

Yacht Master

2 batteries, the other one (AUX Battery backup for electric brakes SBC) is under hood passenger side, large cover with one black plastic nut holding it has a sticker that says battery in trunk. Take nut off and lift front part up this part has your cabin air filter in it, it will pop loose and you will see the AUX battery.

My advise is get a new battery (or 2) nothing is harder on the electrical system than a weak battery, low voltage kills. No battery, no brakes.

zoink

I heard that aux battery should last a long time.... my trunk battery died once already (at 19K miles).

Unless you want the ultra small battery, use roadside assitance to get it replaced. You'll only pay for the battery itself... not a labor (which you will have to if you do it at the stealership).

AMGfan

I've had this problem several times...This will be my third Mercedes battery in my E55. I go out of town 2-3 weeks at a time about twice a year. Either get a spare battery (MB will rape you on labor) or get a battery charger.

I got a CTEK battery charger and I've been happy with it. It is installed in-line with the battery and I just plug the battery charger when I'm away.

http://www.hsgear.biz/ProductInfo~pr...4202-4203.html

I think MB sells them but at a markup. I got mine from Ebay.

Jakpro1

Long as you take her for a good drive, you should be fine on the small one. Worth a check though. Car goes dead, it's the only thing LITERALLY keeping you from certain death or massive injury.