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The main starter battery, dated 43/14, is still strong, holds a charge, and seems fine. However, living in NE Ohio, I'm concerned about its performance and when it will fail on a cold night . What is the role of the auxiliary (AUX) battery in maintaining memory and critical electrical components during the main battery replacement? Should I use a battery tender to ensure the memory items
Yes, you need to provide constant 12 volt power. Normal charging modes on tenders don’t do what you need. For example, when you go to CTEK, Mercedes choice, you need to go to their 7002 series which provides both charging and direct power capabilities. And … there are a few other things you should do, make sure all power consumers are turned off, put the driver window down, put the key at least 3 meters from the car and don’t try to use the cigarette lighter as a plug-in because with the ignition off it’s not connected to the system. Use either alligator clips on the terminals under the hood or an OBD II connector.
I’m not sure about the age of the battery from your description but for what it’s worth, I change both batteries and tires at 5 years regardless of mileage. Haven’t ever had to hitchhike.
It's kinda overkill changing batteries in a Mercedes-Benz in every 5 years but it should provide an extra piece of mind as well .
I still have my Original Main Battery from 2014. I use a Battery Tender when car is sitting most of the time. The Aux Battery was replaced twice since 2014. The Aux Battery and Main Battery are not on the same circuit. So when you use the tender, it is only maintaining the Main battery. I'm in the Low Voltage business, the AUX battery in general should have a lifespan of 3 to 5 years..
Last edited by Nice Ride; Feb 16, 2024 at 12:03 AM.
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.
