SL/R232: Try a Faraday box to reduce battery drain
Thread Starter
Member
Joined: Mar 2023
Posts: 108
Likes: 90
SL55 2023
Try a Faraday box to reduce battery drain
I previously had great battery luck with my 2023 SL55 by double locking the door and keeping the key 20 feet away. However, as I have driven the SL less recently with fewer days of convertible weather, I experienced some low battery warnings that required trickle charging. Based on another post on this forum, I changed my approach to double locking and keeping the key in a Faraday box. Since then I have had no battery warnings at all. Search “faraday box for car keys” on Amazon and you will find many in the $10-$20 price range. I tested mine by bringing the closed box with the key inside next to my SL and it passed the test—it would not unlock the door until I opened the box.
I bought this $13 model but there are many other choices:
Please report here if you have used a faraday key box or decide to give it a try.
I bought this $13 model but there are many other choices:
Please report here if you have used a faraday key box or decide to give it a try.
MBWorld Fanatic!
Joined: Jan 2013
Posts: 1,170
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From: Irvine, California
2022 AMG SL63
I've used one. A bag actually but same principle. I did find that with the bags I misjudged the size needed and had to opt for a larger size (still inexpensive). It's an easy fix. Yes, if we all lived in the "world of should" this wouldn't be necessary but it's not such an inconvenience and like many thing worthwhile once the habit is established it is seamless and takes all of a couple of seconds.
MBWorld Fanatic!
Joined: Oct 2010
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From: Corona Del Mar, CA
2019 SL450, 2019 E450 Luxury Trim Wagon, 2024 BMW I7 xDrive60
Well, our “world of should” is occupied by those who are “glass half full” types and “glass half empty” types. Alas, I belong to the latter group and cannot understand why ANYONE would rejoice at having to lock their car, when the car is sitting in their locked, private garage and then needing to secret their key away in a magic box or bag. As a card carrying member of the GHE group, I would NEVER do those things and would achieve great entertainment from constantly calling MB Roadside Assistance to tow the car into the dealer, so they can try to fix the car properly, so that it operates as stated in the Owner’s Manual.
Several folks here lament the “lead balloon” depreciation the R232’s have experienced. No problem. With the built-in issue of the battery going dead when the SL’s are treated like virtually every other vehicle on the planet, just give the dealer their required number of repair attempts, refuse to jump through their ridiculous hoops and when the car reaches “lemon status,” get all your money back. Depreciation issue solved!
Several folks here lament the “lead balloon” depreciation the R232’s have experienced. No problem. With the built-in issue of the battery going dead when the SL’s are treated like virtually every other vehicle on the planet, just give the dealer their required number of repair attempts, refuse to jump through their ridiculous hoops and when the car reaches “lemon status,” get all your money back. Depreciation issue solved!
Thread Starter
Member
Joined: Mar 2023
Posts: 108
Likes: 90
SL55 2023
Well, our “world of should” is occupied by those who are “glass half full” types and “glass half empty” types. Alas, I belong to the latter group and cannot understand why ANYONE would rejoice at having to lock their car, when the car is sitting in their locked, private garage and then needing to secret their key away in a magic box or bag. As a card carrying member of the GHE group, I would NEVER do those things and would achieve great entertainment from constantly calling MB Roadside Assistance to tow the car into the dealer, so they can try to fix the car properly, so that it operates as stated in the Owner’s Manual.
Several folks here lament the “lead balloon” depreciation the R232’s have experienced. No problem. With the built-in issue of the battery going dead when the SL’s are treated like virtually every other vehicle on the planet, just give the dealer their required number of repair attempts, refuse to jump through their ridiculous hoops and when the car reaches “lemon status,” get all your money back. Depreciation issue solved!
Several folks here lament the “lead balloon” depreciation the R232’s have experienced. No problem. With the built-in issue of the battery going dead when the SL’s are treated like virtually every other vehicle on the planet, just give the dealer their required number of repair attempts, refuse to jump through their ridiculous hoops and when the car reaches “lemon status,” get all your money back. Depreciation issue solved!
MBWorld Fanatic!
Joined: Oct 2010
Posts: 8,125
Likes: 4,353
From: Corona Del Mar, CA
2019 SL450, 2019 E450 Luxury Trim Wagon, 2024 BMW I7 xDrive60
Member
Joined: Feb 2023
Posts: 184
Likes: 138
From: Chicago and Palm Springs
2025 BMW Z4 M40i (Manual); 2025 Lexus NXH Luxury; 2021 Porsche Macan S; 2023 Audi Q5
Well, our “world of should” is occupied by those who are “glass half full” types and “glass half empty” types. Alas, I belong to the latter group and cannot understand why ANYONE would rejoice at having to lock their car, when the car is sitting in their locked, private garage and then needing to secret their key away in a magic box or bag. As a card carrying member of the GHE group, I would NEVER do those things and would achieve great entertainment from constantly calling MB Roadside Assistance to tow the car into the dealer, so they can try to fix the car properly, so that it operates as stated in the Owner’s Manual.
Several folks here lament the “lead balloon” depreciation the R232’s have experienced. No problem. With the built-in issue of the battery going dead when the SL’s are treated like virtually every other vehicle on the planet, just give the dealer their required number of repair attempts, refuse to jump through their ridiculous hoops and when the car reaches “lemon status,” get all your money back. Depreciation issue solved!
Several folks here lament the “lead balloon” depreciation the R232’s have experienced. No problem. With the built-in issue of the battery going dead when the SL’s are treated like virtually every other vehicle on the planet, just give the dealer their required number of repair attempts, refuse to jump through their ridiculous hoops and when the car reaches “lemon status,” get all your money back. Depreciation issue solved!
2. We don’t “rejoice” in locking our cars. We rejoice in the driving experience. For all your criticism of the car, have you driven one? We rejoice in the beauty of the car; while taste is subjective it is generally considered to be a vast improvement over its predecessor. I am glad that you are still smitten with yours.
3. You’ve harped on the depreciation curve, which is bad. Most of us knew the historical depreciation of AMG SLs when we purchased our cars. Yet you’ve chosen to order an electric 7-series sedan, two classes of cars that set records for mind numbing depreciation. Good luck with that, unless you find a reason to lemon law this car also.
4. Buy a current 911 with a lithium battery or any new Ferrari and see what happens if you don’t keep it on a trickle charger.
If my trade off for the enjoyment I get out of my car is having to lock it in the garage, I can live with that. I learned a long time ago that perfection is paralysis.
Last edited by drgek; May 9, 2024 at 10:30 PM.
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MBWorld Fanatic!
Joined: Oct 2010
Posts: 8,125
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From: Corona Del Mar, CA
2019 SL450, 2019 E450 Luxury Trim Wagon, 2024 BMW I7 xDrive60
MBWorld Fanatic!
Joined: Feb 2002
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From: 2000 ft over the FL coast in a B-17
Various
I keep our car keys in a kitchen drawer with our house keys, which is very far from the garage and no battery drain issues locked or un, and they are unlocked most of the time. I also always power the vehicles down by holding in the power button to the radio/mmi etc so everything goes dark before I exit, My M850 actually has a key proximity sensor light that illuminates to let you know the vehicle is still sensing the key…moral of the story - keep the keys far enough away, power down the system and there’s no issue even unlocked.
Member
Joined: Feb 2025
Posts: 135
Likes: 47
I previously had great battery luck with my 2023 SL55 by double locking the door and keeping the key 20 feet away. However, as I have driven the SL less recently with fewer days of convertible weather, I experienced some low battery warnings that required trickle charging. Based on another post on this forum, I changed my approach to double locking and keeping the key in a Faraday box. Since then I have had no battery warnings at all. Search “faraday box for car keys” on Amazon and you will find many in the $10-$20 price range. I tested mine by bringing the closed box with the key inside next to my SL and it passed the test—it would not unlock the door until I opened the box.
I bought this $13 model but there are many other choices:
https://www.amazon.com/gp/product/B0...e?ie=UTF8&th=1
Please report here if you have used a faraday key box or decide to give it a try.
I bought this $13 model but there are many other choices:
https://www.amazon.com/gp/product/B0...e?ie=UTF8&th=1
Please report here if you have used a faraday key box or decide to give it a try.
MBWorld God!
Joined: Dec 2019
Posts: 32,222
Likes: 6,281
Faraday box holds 4 fobs -- free with doggo's flea collar.
https://cimg7.ibsrv.net/gimg/www.mbw...e778c9dabf.jpg
https://cimg7.ibsrv.net/gimg/www.mbw...e778c9dabf.jpg
