Electrical Consumers Offline R230 SL55

cmc

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Nov 14, 2006
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12
Hi All,
I am getting the consumers offline message usually after not driving the car (2004 SL55 AMG) for a couple of days. It goes out after a short while and my thoughts were that the battery is not holding charge and probably needs changing. I am sure this topic has been touched on but I’d like to ask if anyone has had this and if you think my diagnosis is accurate. Is there anything else I should check?

thanks in advance people.
 

E55BOF

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CLS 350 SB, CLS 63 SB, SLK55, FJR1300,
The R230 is well-known for (relatively) heavy residual electrical load when switched off. Check the battery (the one in the boot) is the correct size, and if it is, charge it fully with a trickle charger and see how it goes after that.
 
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cmc

New Member
Joined
Nov 14, 2006
Messages
12
Thanks, battery looks okay size wise. Will put a trickle on it and see how it goes.
 

Brabus SL

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Oct 10, 2008
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Location
London
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Brabus SL55 K8
Hi All,
I am getting the consumers offline message usually after not driving the car (2004 SL55 AMG) for a couple of days. It goes out after a short while and my thoughts were that the battery is not holding ca harge and probably needs changing. I am sure this topic has been touched on but I’d like to ask if anyone has had this and if you think my diagnosis is accurate. Is there anything else I should check?

thanks in advance people.

This is normal when left unused for a couple of weeks. Sometimes, it might even happen after a few days - depending on the age of the battery and the care the battery has had. If the battery has been allowed to go flat, they tend not to fully recover - meaning that when you next try to fully charge it, it will only accept a limited amount of charge.

The rear battery in the SL55 should be an AGM battery and not a led acid one. The AGM battery (which are now commonly used in cars with stop-start technology) can recover from a deep discharge without any issues. AGM batteries also hold their charge for much longer than a lead-acid battery.

The charging system on the SL55 AMG is designed to charge an AGM battery (AGM batteries are charged differently to lead-acid ones). AGM batteries used to be quite costly, but not anymore, I have owned my SL55 since 2008, like many new owners of the SL55 AMG I experienced the same as you. A replacement AGM battery back then for the SL55 AMG would cost around £225! Now, you can buy an 096 AGM VARTA or 096 AGM Exide for around £130 (if you look around).

I would not recommend that you fit a lead acid or equivalent. It will work, but it's life will be greatly reduced, especially if you don't connect a battery smart charger conditioner. With my SL55 AMG, I can leave it for a month without it being connected to a charger and I still don't get the consumers offline message. However, I do normally have a smart charger connected to the rear. I also have a separate charger on the front battery. Contrary to popular belief, charging the rear battery does not charge the front battery, so if your car sits unused for some time - like during the winter, it would be better for each of the batteries to be connected to a smart charger.

The front battery has two purposes - to start the engine and for the brakes. If you ever get a red warning with a battery symbol message in the dash display, safely STOP the car, do not drive it. You will have limited amounts of brake pedal presses before the breaks totally stop working.

The rear battery is for everything else electronic in the car. Even after the car goes to sleep (around 15 mins after locking the door) the electronics on the SL55 are slowly consuming. It is for this reason that the rear battery looses power. But, after saying all of the above, you could also have a battery drain caused by a device which isn't switching off.

I hope this help.
 

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