SL/R231: Winterising R231 2013 SL 550 batteries
Thread Starter
Junior Member
Joined: Apr 2021
Posts: 71
Likes: 5
From: Canada
2013 SL 550 R231
Winterising R231 2013 SL 550 batteries
Hello everyone,
I am winterising my 2013 SL 550 R231 for about 5 months and I need some in formation as I have read conflicting answers regarding my question.
My question is trickle charging the car's battery or batteries.
I know that there is the main battery in the trunk, it can be reached (charged) through the charging posts in the engine compartment.
The second battery is located below a compartment behind the passenger seat.
Witch battery needs the trickle charge or do both need be charged?
Is a 1 amp. trickle charger (s) powerful enough ?
Thanks for your help
I am winterising my 2013 SL 550 R231 for about 5 months and I need some in formation as I have read conflicting answers regarding my question.
My question is trickle charging the car's battery or batteries.
I know that there is the main battery in the trunk, it can be reached (charged) through the charging posts in the engine compartment.
The second battery is located below a compartment behind the passenger seat.
Witch battery needs the trickle charge or do both need be charged?
Is a 1 amp. trickle charger (s) powerful enough ?
Thanks for your help
Junior Member
Joined: Nov 2020
Posts: 44
Likes: 13
2003 SL500, 2013 SL550
Hello everyone,
I am winterising my 2013 SL 550 R231 for about 5 months and I need some in formation as I have read conflicting answers regarding my question.
My question is trickle charging the car's battery or batteries.
I know that there is the main battery in the trunk, it can be reached (charged) through the charging posts in the engine compartment.
The second battery is located below a compartment behind the passenger seat.
Witch battery needs the trickle charge or do both need be charged?
Is a 1 amp. trickle charger (s) powerful enough ?
Thanks for your help
I am winterising my 2013 SL 550 R231 for about 5 months and I need some in formation as I have read conflicting answers regarding my question.
My question is trickle charging the car's battery or batteries.
I know that there is the main battery in the trunk, it can be reached (charged) through the charging posts in the engine compartment.
The second battery is located below a compartment behind the passenger seat.
Witch battery needs the trickle charge or do both need be charged?
Is a 1 amp. trickle charger (s) powerful enough ?
Thanks for your help
I don't have a definite answer but a pretty educated one for you. I own a 2003 SL500 and it too has two batteries. The accessory battery in the trunk and the startup battery under the hood. I leave the 2003 in Florida and only use it in the winter months. I use a trickle charger on the accessory battery in the trunk and every time I go to Florida it starts fine and runs fine. I think in large part because I keep the trickle charger on the accessory battery in the trunk.
I now own a 2013 SL550 and think I will do the same thing when I go to Florida for the winter and that is put a trickle charger on the accessory battery which is located behind the passenger seat.
I look forward to any more experienced R231 owners who have needed to leave their cars garaged for months at a time, especially during the winter.
Thanks!
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Joined: May 2002
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From: Land of 10,000 lakes
AMG GTC Roadster, E63s Ed.1, M8 Comp. Coupe
Slightly different answer from me. Doesn’t matter how many batteries the car has.
You usually use the charge points in the car if it has them. That means under the hood. The cars charging system takes care of batteries.
Just like in dealer showrooms (normal times when dealers have inventory) cars are usually plugged in on the charge points.
You usually use the charge points in the car if it has them. That means under the hood. The cars charging system takes care of batteries.
Just like in dealer showrooms (normal times when dealers have inventory) cars are usually plugged in on the charge points.
Senior Member
Joined: Oct 2019
Posts: 293
Likes: 153
From: Nova Scotia, Canada
2019 SL450; 2023 M850i coupe
Some relevant info in this thread starting at post 23. https://mbworld.org/forums/sl-class-...tery-type.html
Super Moderator
Joined: May 2002
Posts: 10,534
Likes: 3,669
From: Land of 10,000 lakes
AMG GTC Roadster, E63s Ed.1, M8 Comp. Coupe
Some relevant info in this thread starting at post 23. https://mbworld.org/forums/sl-class-...tery-type.html
Eventually we decided that keeping the SL in storage for the winter was a waste and put on some snows instead. They drive great in the snow
Something we reversed for the AMG GTC. That car is back in storage and gets trickle charged via the cigarette lighter in the trunk…
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Senior Member
Joined: Oct 2019
Posts: 293
Likes: 153
From: Nova Scotia, Canada
2019 SL450; 2023 M850i coupe
Great info! But it makes the point via measurement that it’s not necessary to charge the accessory battery anyway. We have had our SL’s sitting for up to 5 months for many years either with a single trickle charger to the charge point or nothing at all (just starting the car occasionally and letting it run for a bit but that was more for the R230’s).
Eventually we decided that keeping the SL in storage for the winter was a waste and put on some snows instead. They drive great in the snow
Something we reversed for the AMG GTC. That car is back in storage and gets trickle charged via the cigarette lighter in the trunk…
Eventually we decided that keeping the SL in storage for the winter was a waste and put on some snows instead. They drive great in the snow
Something we reversed for the AMG GTC. That car is back in storage and gets trickle charged via the cigarette lighter in the trunk…
The voltage drop on the Aux battery (measured at approx. 1.5 mV a week in warm weather) is so low that it hardly seems necessary to keep a maintainer on it full time while in storage.
It’s been suggested that the Aux battery will take a charge from the battery posts under the hood, but only once the Aux battery falls below a threshold of approx. 11 volts. 11 volts is too low to allow an AGM battery to sit, so topping up sooner (at 12V) from the Aux battery terminals behind the passenger seat is probably a good idea if and when necessary.
Last edited by hornethandler; Dec 4, 2021 at 01:31 PM.
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Thread Starter
Junior Member
Joined: Apr 2021
Posts: 71
Likes: 5
From: Canada
2013 SL 550 R231
That’s the confirmation I was looking for. There are many contradictions regarding this issue for the 2013 SL550;R 231
I was under the impression that you connect the trickle charger directly to the charging posts in the engine compartment ( passenger side firewall )
and this directly charges the auxiliary battery in the trunk without direct connection to it needed. No need to connect a trickle charger to the main battery behind the passenger seat as it will draw power from the auxiliary battery in the trunk if needed
i hope that finally I have it wright, let me know Wolfman
Best Regards
SLdoug
I was under the impression that you connect the trickle charger directly to the charging posts in the engine compartment ( passenger side firewall )
and this directly charges the auxiliary battery in the trunk without direct connection to it needed. No need to connect a trickle charger to the main battery behind the passenger seat as it will draw power from the auxiliary battery in the trunk if needed
i hope that finally I have it wright, let me know Wolfman
Best Regards
SLdoug
Senior Member
Joined: Oct 2019
Posts: 293
Likes: 153
From: Nova Scotia, Canada
2019 SL450; 2023 M850i coupe
That’s the confirmation I was looking for. There are many contradictions regarding this issue for the 2013 SL550;R 231
I was under the impression that you connect the trickle charger directly to the charging posts in the engine compartment ( passenger side firewall )
and this directly charges the auxiliary battery in the trunk without direct connection to it needed. No need to connect a trickle charger to the main battery behind the passenger seat as it will draw power from the auxiliary battery in the trunk if needed
i hope that finally I have it wright, let me know Wolfman
Best Regards
SLdoug
I was under the impression that you connect the trickle charger directly to the charging posts in the engine compartment ( passenger side firewall )
and this directly charges the auxiliary battery in the trunk without direct connection to it needed. No need to connect a trickle charger to the main battery behind the passenger seat as it will draw power from the auxiliary battery in the trunk if needed
i hope that finally I have it wright, let me know Wolfman
Best Regards
SLdoug
- The Main (large) battery is in the trunk and the Aux. (small) battery is behind the passenger seat.
- The battery posts under the hood are connected to the Main battery.
- The Aux “may” be charged from the battery posts under the hood but only if the Aux. drops below approx. 11 volts.
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Joined: Jan 2016
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From: Brookshire, Texas & Cat Spring, Texas
2019 SL550/2023 EQS 580 SUV
Number 3 is correct. The aux battery through a one way connection can be charged by the main starter battery. Just connect a battery maintainer to the posts under the hood and all will be fine. As mentioned above cars sit from the factory to the dealership for long periods of time and it would be crazy/expensive for the dealerships to dive into the compartment behind the passenger seat just to charge the aux battery.
MBWorld Fanatic!
Joined: Dec 2015
Posts: 1,634
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From: Hagerstown MD
2015 SL400; 2019 X5M40i
Number 3 is correct. The aux battery through a one way connection can be charged by the main starter battery. Just connect a battery maintainer to the posts under the hood and all will be fine. As mentioned above cars sit from the factory to the dealership for long periods of time and it would be crazy/expensive for the dealerships to dive into the compartment behind the passenger seat just to charge the aux battery.
Senior Member
Joined: Oct 2019
Posts: 293
Likes: 153
From: Nova Scotia, Canada
2019 SL450; 2023 M850i coupe
Senior Member
Joined: Jul 2013
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From: Europe, but from Norway
89 SL500 Silver ,97 SL500 Carlsson 04 Mercedes SL55 AMG , 07 Mercedes SL55 AMG convertedBlack series
how long time can the sl500 sit in garage in minus ,before batteri drop? I read somewhere the 2013 models have aux batteri inside fotwell passenger side, Then later models moved pos bhind passenger side.
MBWorld Fanatic!
Joined: Dec 2015
Posts: 1,634
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From: Hagerstown MD
2015 SL400; 2019 X5M40i
Depends on the condition of your batteries but I would definitely use a battery maintainer on the terminals under the hood. Supposedly it will also keep the auxiliary battery behind the passenger seat from going below a level which would render it ineffective.
