Second Battery - Mercedes-Benz Forum

LinkBack Thread Tools Display Modes
post #1 of 6 (permalink) Old 10-25-2012, 01:47 PM Thread Starter
BenzWorld Member
Date registered: May 2010
Vehicle: SL550, GL550 & E350(wagon)
Location: Tampa
Posts: 66
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
(Thread Starter)
Second Battery

Hi All,

Does the second battery get any charging when the car is running?

I routinely hook up my trickle charger (1.25 amp) and it soaks for two or three days to bring the second battery to "full charge". I thought it was because my SL was a victim of short trips. But.......I just returned from 500 mile Interstae trip and same deal...took a two day trickle soak.

If this is normal...fine. If not, perhaps it's a cuurent drain.

Comments please.

Thx, Don
eckerson89 is offline  
Sponsored Links
post #2 of 6 (permalink) Old 11-27-2012, 11:35 AM
BenzWorld Newbie
Date registered: May 2010
Vehicle: 2013 SL550, 2003 SL500
Location: Ft. Lauderdale, FL
Posts: 4
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
Hi Don,
I've had the same experience. What you refer to as the second battery (in trunk) is actually the main vehicle battery. I'm sure that it gets charged (I've measured the voltage) when the engine is running.
Don't know why it still takes a charge after a long run. I did read somewhere that there are vehicle systems that are constantly drawing current, even with everything off and locked. Perhaps that is the cause.
Take care,
handy6699 is offline  
post #3 of 6 (permalink) Old 12-05-2012, 06:33 PM
BenzWorld Member
Date registered: Nov 2012
Vehicle: 2000 BMW M5, 1997 F250, 1998 Altima, 2005 Honda Repsol 1000RR, 22FT Bayliner Capri Bowrider 5.0L
Location: North Suburbs of Chicago
Posts: 106
Mentioned: 0 Post(s)
Quoted: 1 Post(s)
the venicle is very smart, it only uses the starter battery for starting, and only charges the starter battery when it needs to. dont be alarmed.. just drive and be happy!
Master Certified is offline  
post #4 of 6 (permalink) Old 12-27-2012, 11:41 AM
Undercover Moderator
SL BRABUS's Avatar
Date registered: Mar 2007
Vehicle: SL BRABUS 5.8 Silver Arrow, SL BRABUS B11, S Class diplomat ride, ML55 wife war horse grocery getter
Location: Near BRABUS, CA. USA
Posts: 5,088
Mentioned: 10 Post(s)
Quoted: 195 Post(s)
Lifetime Premium Member
Originally Posted by eckerson89 View Post
Hi All,

Does the second battery get any charging when the car is running?

Comments please.

Thx, Don
Yes, just like the R230 SL....

Horsepower: enough power to go from point A to point B
Torque: enough to get the car moving

0-60 mph: not in a rush
0-1/4 mile: about 5 minutes @ 2mph because no need to showoff

Pictures of my SL collection & Pictures of my S Class ride

My favorite topic, What kind of watch do you guys wear with your Benz...??
SL BRABUS is offline  
post #5 of 6 (permalink) Old 05-15-2013, 07:14 AM
BenzWorld Member
Date registered: Feb 2007
Posts: 75
Mentioned: 0 Post(s)
Quoted: 3 Post(s)
Second battery

Found the main battery in the trunk but I'm told by the Dealer that the smaller battery, which needs occasional charging, is somewhere under the passengers seat. I can't find it! I'm told that should it have to be replaced the car has to go to the Dealer where it takes about 2 hours to swap the old for the new. At $125/hour plus the cost of a new Mercedes battery that should come to about $500

Does anyone know where to get a look at a shop manual?
islander2 is offline  
post #6 of 6 (permalink) Old 05-15-2013, 11:40 AM
BenzWorld Junior Member
Date registered: Feb 2013
Posts: 36
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
Smaller battery sits in a compartment behind passenger seat under removeable lid.
California John is offline  
Sponsored Links

  Mercedes-Benz Forum > Mercedes-Benz Roadster Forums > R231 SL-Class

Quick Reply

Register Now

In order to be able to post messages on the Mercedes-Benz Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Title goes here

video goes here
description goes here. Read Full Story
For the best viewing experience please update your browser to Google Chrome