SL/R231: Battery tender recommendation
Thread Starter
Newbie
Joined: Nov 2022
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2020 SL450, 2022 GLE63S
Battery tender recommendation
I recently purchased a new (to me) 2020 SL450 and am looking for a recommendation for a battery tender as well where to plug it in - trunk or somewhere inside the car. Thanks, Ron
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Joined: Jan 2017
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From: God's County (Yorkshire)
Shanks’s Pony
Many people use a CTEK charger/maintainer(the unit sold by MB, Porsche, Bentley and some others are all rebranded CTEK) . My SL is currently on one.
Newbie
Joined: May 2018
Posts: 13
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From: Chicago
SL550, GLK250, Stelvio Quadrifoglio, M4 GTS, 996 4S, Evora 400
Have been replacing the older Battery Tender and CTEK units when the fail with Noco Genius1 units. We have a mix of cars/motorcycles in our storage with various battery types, and the flexibility of the Noco to support Lead Acid, AGM, Lithium battery types make them very convenient to use.
I have mine connected to the battery in the truck, and just added one to my Aux battery when I replaced it last month,
I have mine connected to the battery in the truck, and just added one to my Aux battery when I replaced it last month,
Member
Joined: Aug 2022
Posts: 111
Likes: 44
From: Bainsville, Ontario, Canada
SL 550 (2014) Kia Sorento (2016)
I have one charger for each battery on an R231. I'm not sure about the R230 but on the R231 the batteries are separated from the charging post in the front. The trunk battery is directly connected to the jump post. The aux battery is not. The r230 setup is different.
Simple test is to hook up a charger to the jump post or the trunk battery (same circuit) then read the voltage at the trunk battery. It will be anywhere from 13.8 to 14.6 volts which is the output voltage from the charger. Then test the voltage at the terminals of the aux battery behind the passenger seat. It will read no more than 12.6 volts which indicates it's not on the charging circuit.
Remember, this applies to an R231.
Simple test is to hook up a charger to the jump post or the trunk battery (same circuit) then read the voltage at the trunk battery. It will be anywhere from 13.8 to 14.6 volts which is the output voltage from the charger. Then test the voltage at the terminals of the aux battery behind the passenger seat. It will read no more than 12.6 volts which indicates it's not on the charging circuit.
Remember, this applies to an R231.
MBWorld Fanatic!
Joined: Jan 2017
Posts: 1,040
Likes: 234
From: God's County (Yorkshire)
Shanks’s Pony
I have one charger for each battery on an R231. I'm not sure about the R230 but on the R231 the batteries are separated from the charging post in the front. The trunk battery is directly connected to the jump post. The aux battery is not. The r230 setup is different.
Simple test is to hook up a charger to the jump post or the trunk battery (same circuit) then read the voltage at the trunk battery. It will be anywhere from 13.8 to 14.6 volts which is the output voltage from the charger. Then test the voltage at the terminals of the aux battery behind the passenger seat. It will read no more than 12.6 volts which indicates it's not on the charging circuit.
Remember, this applies to an R231.
Simple test is to hook up a charger to the jump post or the trunk battery (same circuit) then read the voltage at the trunk battery. It will be anywhere from 13.8 to 14.6 volts which is the output voltage from the charger. Then test the voltage at the terminals of the aux battery behind the passenger seat. It will read no more than 12.6 volts which indicates it's not on the charging circuit.
Remember, this applies to an R231.
Thread Starter
Newbie
Joined: Nov 2022
Posts: 10
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2020 SL450, 2022 GLE63S
Ron
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From: Pachuta, MS
2015 SL400
Hi all,
is there a particular CTEK charger you guys use? There are a bunch of different ones on Amazon. I actually used the cigarette lighter version (Porsche brand, but a CTEK) on my ‘15 911…anyone gone that route? I probably need to check and see if the battery is an AGM.
Any advice is appreciated, as the SL is now in stall 3 and won’t see daylight until probably April.
JHop
is there a particular CTEK charger you guys use? There are a bunch of different ones on Amazon. I actually used the cigarette lighter version (Porsche brand, but a CTEK) on my ‘15 911…anyone gone that route? I probably need to check and see if the battery is an AGM.
Any advice is appreciated, as the SL is now in stall 3 and won’t see daylight until probably April.
JHop
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MBWorld Fanatic!
Joined: Jan 2017
Posts: 1,040
Likes: 234
From: God's County (Yorkshire)
Shanks’s Pony
Hi all,
is there a particular CTEK charger you guys use? There are a bunch of different ones on Amazon. I actually used the cigarette lighter version (Porsche brand, but a CTEK) on my ‘15 911…anyone gone that route? I probably need to check and see if the battery is an AGM.
Any advice is appreciated, as the SL is now in stall 3 and won’t see daylight until probably April.
JHop
is there a particular CTEK charger you guys use? There are a bunch of different ones on Amazon. I actually used the cigarette lighter version (Porsche brand, but a CTEK) on my ‘15 911…anyone gone that route? I probably need to check and see if the battery is an AGM.
Any advice is appreciated, as the SL is now in stall 3 and won’t see daylight until probably April.
JHop
Mine is a ~14 year old MSX7 (i.e. 7 Amp) which I connect to the jump start points (as recommend by MB for charging).
If it is purely for maintenance you can easily use a much lower Amepere ratting.
I don’t believe the 12v socket route will work as they are supposedly isolated when the engine is off.
Thread Starter
Newbie
Joined: Nov 2022
Posts: 10
Likes: 5
2020 SL450, 2022 GLE63S
Hi all,
is there a particular CTEK charger you guys use? There are a bunch of different ones on Amazon. I actually used the cigarette lighter version (Porsche brand, but a CTEK) on my ‘15 911…anyone gone that route? I probably need to check and see if the battery is an AGM.
Any advice is appreciated, as the SL is now in stall 3 and won’t see daylight until probably April.
JHop
is there a particular CTEK charger you guys use? There are a bunch of different ones on Amazon. I actually used the cigarette lighter version (Porsche brand, but a CTEK) on my ‘15 911…anyone gone that route? I probably need to check and see if the battery is an AGM.
Any advice is appreciated, as the SL is now in stall 3 and won’t see daylight until probably April.
JHop
It comes with both battery post connectors as well as alligator clips.
Ron
