can you trickle charge the aux battery? - Page 2

Jan 19, 2023 | 01:29 AM

#26

stug477

Newbie

Joined: Aug 2017

Posts: 13

Likes: 0

From: Atlantic City, NJ

2005 Clk500 & 2017 S550 Base

How can you trickle charge the Auxiliary battery with out taking the the trunk apart? 2017 S550 Base

Feb 1, 2023 | 11:22 PM

#27

Delagueto

Newbie

Joined: Feb 2023

Posts: 1

Likes: 0

CLS55 AMG

I changed the 2 batteries, I drove very little in the car, it was stopped for 5 days. Now it is giving the message of comfort items disconnected, the mechanic said I need to rotate more to "adjust" the tension. makes sense? I am suspicious of the auxiliary battery, it is not agm, could that be it?

Feb 2, 2023 | 08:37 AM

#28

machild

MBWorld Fanatic!

Joined: Jun 2020

Posts: 1,177

Likes: 314

2006 CLS55 AMG, 2005 SLK 350 AMG

Quote:

Originally Posted by Delagueto

When you get the message that 'Comfort Items Disconnected' it is telling you there is a low voltage issue with the main battery. The only purpose of the aux battery is to provide a back up power soruce for the electric brake system in the case of a major electrical failure and the main battery may not provide sufficient battery power to stop the car. The main battery is responsible for the entire car in normal operating conditions. So, when you get that message it means the main battery is not charged sufficiently to operate all the various systems on the car. This can occur after the car has been sitting for a long enough period that the main battery is somewhat low but not so low the car won't start. When you start it and the battery is low it switches off items in groups and will do that for various groups to as needed. If the battery is able to recharge from the car electrical system then once it is fully charged the message on the dash changes to notify the Comfort Items are functional again.

Since the aux battery is only a back up for braking, it is monitored by the car system (about 15 minutes after starting the car) and will charge if it has fallen below a voltage threshold. That battery - along with the main battery, should be AGM. A float charger on the main battery is a must for any car that is not driven regularly.

Feb 2, 2023 | 02:22 PM

#29

nd-photo.nl

MBWorld Fanatic!

Joined: May 2022

Posts: 1,917

Likes: 499

From: The Netherlands

2005 CLS55 AMG W219 C219

Check the voltage when the car has been sitting for a day or so. If the voltage is too low, then it needs to be replaced.

Around 11.8v or lower is reason enough to consider replacing them.