SL/R231: HELP! Completely dead
Thread Starter
Newbie
Joined: Apr 2023
Posts: 8
Likes: 3
From: Atlanta
SL450
HELP! Completely dead
Hello everyone. I have a 2017 SL450 that showed no issues when I parked it a few days ago with the top down in the garage. This morning, the car was completely dead. No lights, no horn no dash lights nothing at all. How do I go about fixing this if I can't open the trunk and if I could, the top is down so how can I get to the battery? I've only had the car about 6 months so I'm still fairly new to the SL and its inner workings. Thanks in advance.
Thread Starter
Newbie
Joined: Apr 2023
Posts: 8
Likes: 3
From: Atlanta
SL450
I tried jumping it off with my wifes car but the batter was too dead. I did at least get all the dash light to come on and it attempted a "weak" start. Is it safe to connect a battery charger to the jump posts under the hood?
MBWorld Fanatic!
Joined: Feb 2021
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From: Nor-Cal
2020 GLC300 -2014 Sl550 - 1997 SL600
Hello everyone. I have a 2017 SL450 that showed no issues when I parked it a few days ago with the top down in the garage. This morning, the car was completely dead. No lights, no horn no dash lights nothing at all. How do I go about fixing this if I can't open the trunk and if I could, the top is down so how can I get to the battery? I've only had the car about 6 months so I'm still fairly new to the SL and its inner workings. Thanks in advance.
These cars tend to be pretty hard on batteries, and typically can fail without the "normal" warning signs some cars will exhibit when a battery is getting old.
You can only determine the true condition of these batteries under testing. BTW if you're not aware, there are two batteries in these cars. While the auxiliary battery will typically flash a message on the dashboard. The main batteries will not and should be replaced somewhat regularly.
The best place to jump these cars is under the hood. You can also try to put an AGM comparable charger on it overnight too. But chances are the battery may be too run down....
Good Luck
Last edited by crconsulting; Apr 5, 2023 at 11:46 AM.
MBWorld Fanatic!
Joined: Feb 2021
Posts: 1,419
Likes: 738
From: Nor-Cal
2020 GLC300 -2014 Sl550 - 1997 SL600
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MBWorld Fanatic!
Joined: Feb 2021
Posts: 1,419
Likes: 738
From: Nor-Cal
2020 GLC300 -2014 Sl550 - 1997 SL600
Yeah, you're going to have to get creative but you're going to want to have something to prop that roof up.
I usually make custom props like that out of wood. As long as there's not too munch weight on them!
Last edited by crconsulting; Apr 5, 2023 at 12:18 PM.
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Thread Starter
Newbie
Joined: Apr 2023
Posts: 8
Likes: 3
From: Atlanta
SL450
MBWorld Fanatic!
Joined: Feb 2021
Posts: 1,419
Likes: 738
From: Nor-Cal
2020 GLC300 -2014 Sl550 - 1997 SL600
Here's a good thread to read:
https://mbworld.org/forums/sl-class-...ent-guide.html
Good Luck!
Last edited by crconsulting; Apr 5, 2023 at 12:39 PM.
Thread Starter
Newbie
Joined: Apr 2023
Posts: 8
Likes: 3
From: Atlanta
SL450
As long as you can access it, you should be smooth sailing. Just be careful not to arc/short those terminals. Make sure you get a comparable battery. If you have any doubts, just get one from MB. It will probably last the longest anyways.
Here's a good thread to read:
https://mbworld.org/forums/sl-class-...ent-guide.html
Good Luck!
Here's a good thread to read:
https://mbworld.org/forums/sl-class-...ent-guide.html
Good Luck!
Newbie
Joined: Jul 2025
Posts: 2
Likes: 0
SL550 R23 2015
Hello everyone. I have a 2017 SL450 that showed no issues when I parked it a few days ago with the top down in the garage. This morning, the car was completely dead. No lights, no horn no dash lights nothing at all. How do I go about fixing this if I can't open the trunk and if I could, the top is down so how can I get to the battery? I've only had the car about 6 months so I'm still fairly new to the SL and its inner workings. Thanks in advance.
There is a place to insert the key under the edge of the trunk lid.
Once in the trunk you can pull up the 2 covers and get to the battery.
(replied to this old post so it doesn't stay a dead end thread / question)
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