SL55/63/65/R230 AMG: SL55 convenience battery drained after 1-2h idle
09-28-2015, 12:16 PM
#1
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2005 SL55
SL55 convenience battery drained after 1-2h idle
Hi all
My SL55 is currently at the MB dealer, with a new electric problem. I have checked forum and figured I might have ruined it because I've had a charger on the battery while it has been stocked for winter (constantly said "fully charged", but i guess at some short periods it have been charging) - although I haven't had any problems for the first 3-4 months after this, I recently had it parked for roughly 4 weeks while traveling, and when I came back, it was dead. I expected that, normal error msg with convenience functions unavailable - after 1h of driving it said now available again.
However, I then parked it, went shopping, came back after 1,5-2h, and it was dead again. Turned on, drove a bit, got the red battery error, turned off, immediately turned on, error gone. This repeated itself many times. The engine battery is always good and running.
MB dealer have had it for a week and done a lot of trouble shooting, and their judgement now is to replace the generator and "front computer", whatever that is.. I am a bit unsure how to attack this - wonder if any of you have had the same problem?
Thank you very much in advance.
My SL55 is currently at the MB dealer, with a new electric problem. I have checked forum and figured I might have ruined it because I've had a charger on the battery while it has been stocked for winter (constantly said "fully charged", but i guess at some short periods it have been charging) - although I haven't had any problems for the first 3-4 months after this, I recently had it parked for roughly 4 weeks while traveling, and when I came back, it was dead. I expected that, normal error msg with convenience functions unavailable - after 1h of driving it said now available again.
However, I then parked it, went shopping, came back after 1,5-2h, and it was dead again. Turned on, drove a bit, got the red battery error, turned off, immediately turned on, error gone. This repeated itself many times. The engine battery is always good and running.
MB dealer have had it for a week and done a lot of trouble shooting, and their judgement now is to replace the generator and "front computer", whatever that is.. I am a bit unsure how to attack this - wonder if any of you have had the same problem?
Thank you very much in advance.
09-29-2015, 12:46 AM
#2
Senior Member
I was having a similar problem with my SL63 but replaced the battery and it has been fine since. I would drive to work in the morning and the battery was dead by the end of the day.
It has been a week since I replaced the battery and so far so good. I think part of my issue may have been running an incorrect battery. I had the car stored at my father-in-laws last winter while I was building a new garage, the battery died while it was there (the car was stored for over a year in total) and he was kind enough to pick me up a replacement. What I learned recently though is not many battery places even know what this battery is, let alone stock it.
James
It has been a week since I replaced the battery and so far so good. I think part of my issue may have been running an incorrect battery. I had the car stored at my father-in-laws last winter while I was building a new garage, the battery died while it was there (the car was stored for over a year in total) and he was kind enough to pick me up a replacement. What I learned recently though is not many battery places even know what this battery is, let alone stock it.
James
09-29-2015, 09:15 AM
#3
Senior Member
My guess is if you install a good new AGM battery of the correct size, this problem will be solved. Also, buy a CTek battery charger, and connect it any time you are not going to drive the car at least once in the next week. Leave it connected until you are going to drive it. I hard wired the 'eyelet' connector to the battery terminals, and when I connect the charger, I leave the trunk lid open a few inches, so I don't forget to unplug before driving off!
I found the AGM Duralast battery was over $100 cheaper than the 'MB labeled' battery (MB does not MAKE batteries), and had a 3 year warranty while the MB warranty was 2 years. The Duralast battery was about 1/16" too long for the rear hold down to fit. So I elongated the hole in that hold down plastic piece where the bolt passes through to allow a perfect fit. By purchasing the Duralast battery you will save enough to pay for the CTek maintainer (about $70, same item at MB with their label is about $125)
Good luck
I found the AGM Duralast battery was over $100 cheaper than the 'MB labeled' battery (MB does not MAKE batteries), and had a 3 year warranty while the MB warranty was 2 years. The Duralast battery was about 1/16" too long for the rear hold down to fit. So I elongated the hole in that hold down plastic piece where the bolt passes through to allow a perfect fit. By purchasing the Duralast battery you will save enough to pay for the CTek maintainer (about $70, same item at MB with their label is about $125)
Good luck
05-09-2017, 10:26 PM
#4
Member
Ejbrock
+1 on keeping your battery on a Ctek unit when not in use. The accessory battery is constantly being drained with all the electronics in the car.
+1 on keeping your battery on a Ctek unit when not in use. The accessory battery is constantly being drained with all the electronics in the car.
05-10-2017, 06:31 PM
#5
Member
I have had this issue as well..
I have an aftermarket battery in the trunk and my brother (a mechanic) tested the battery and it is fine. He fixed my soft close and will be doing a service B next week with him and we will look at this. The battery light came on when he disconnected the battery to test it. Once it was reconnected, the light came on. I drove it for a couple days and eventually it hasn't come on again. So back to the OP, if I don't drive the car for a while, I get the "convenience functions unavailable" which run on this trunk battery. I need to drive it more or possibly get a new battery, but I will make sure my brother charges it up 100%. I will keep you posted. Letting these cars sit is not good for them at all..
Cheers!
Shaun
Cheers!
Shaun
05-11-2017, 12:31 PM
#6
Member
Ejbrock
I keep my accessory battery on a Ctek 3300 unit when I am not driving my SL55. Since doing this I have not had any problems.
Good Luck
I keep my accessory battery on a Ctek 3300 unit when I am not driving my SL55. Since doing this I have not had any problems.
Good Luck
12-10-2018, 01:51 AM
#7
MBWorld Fanatic!
If the convenience battery is more than 4 years old, I would replace it first to see if that solves the problem. Even if you use an official MB battery, it will be much less expensive than replacing anything else, never mind the dealer costs to diagnose.
These AGM batteries suffer irreversible damage if allowed to go completely flat which is why the CTEK conditioner is a must have. Modern cars require a minimum of power when not in use but not so the R230 whose electronics date from the late 90s. That’s why the battery goes flat so quickly. This is not a car to leave at the airport for several weeks.
I’ve had my SL55 since September 2002, so it is now 16 years old and I am on my fourth battery. As the car ages, it is getting expensive to maintain. A major maintenance service is typically 20-25% of what the dealer would offer for the car in part exchange.
These AGM batteries suffer irreversible damage if allowed to go completely flat which is why the CTEK conditioner is a must have. Modern cars require a minimum of power when not in use but not so the R230 whose electronics date from the late 90s. That’s why the battery goes flat so quickly. This is not a car to leave at the airport for several weeks.
I’ve had my SL55 since September 2002, so it is now 16 years old and I am on my fourth battery. As the car ages, it is getting expensive to maintain. A major maintenance service is typically 20-25% of what the dealer would offer for the car in part exchange.
