Im having some strange starting problems. Sometimes the car can sit for a month or two and will start right up other times it won't and I have to jump it I replaced the rear battery. Just now I went for a ride in it I had to jump it I drove it for like 20 miles on the interstate stopped to get gas and I had to jump it I'm not sure what's going on here when I got home I put a little trickle charger on the start (front) battery and it was green which means it's good. I checked it with a voltmeter and had 12.6 V I'm not sure if there's a sensor somewhere or relay that's causing problems any ideas?

 

The front battery is for the starter. If it is not charging, you could have a problem with the alternator, or, the battery controller. A quick test is to put a voltmeter on the batteries. At idle, both should register about 14v, but the battery controller can alter this, so truly, you may need SDS to get a proper diagnosis.

 

I did that and both batteries show 14.2 volts.
Pulled the start battery and took it to Advance auto and had it tested.
It showed about 250 amps!

Purchased a new one from Advance that is a duplicate of the MB Battery.

 

So all is well now? For the record, I like Advance Auto's batteries. They seem to use the same suppliers as genuine MBZ, but with better warranties.

 

I'll know if all is well Friday when I take the Badmobile to Cruisin the Coast.

 

Well ????

 

There is a standby mode to preserve battery charge for long term storage. Read the manual. Another option is a simple, cheap trickle charger.

 

I can't find anything about a "standby" mode. This is all that's in my OM regarding battery discharging:

http://benzbits.com/R230/JumpStarting.pdf

According to it, the "proper procedure" is to have your dealer disconnect the battery, which of course, makes no sense unless you intend to store the vehicle at the dealer!

The best option is to use a trickle charger. Here's the genuine MBZ part:

http://www.mboemparts.com/?p=catalog...str=0009820221

But this is nothing more than a CTEK 3300:

http://smartercharger.com/battery-chargers/#CTEK Multi US 3300

 

Page 150
Activating standby mode.
In the index its under vehicle.
Worst manual bar none!
I knew I had read it but still took me 10 min to find.

 

What model/year is your SL? I searched my manual (PDF) for "standby" and "stand-by" - no matches.

 

Just realized Im in the wrong model forum!
Sorry, I was refferencing the w213 new E class.

 

Well, that makes sense! I had never heard of standby mode on the R230. I do know that some people will put a quick disconnect on the rear consumer battery, but that's not factory equipment. In my case, I drive mine every day, or at least several times a week, so no need for this - the advantages of living in The South where I don;t have to worry about putting the car up for the winter.