Tips for Reducing Battery Drain
Thread Starter
Newbie
Joined: Jan 2026
Posts: 8
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From: North Cackalackey
2011 ML550, 2020 GL63 SUV
Tips for Reducing Battery Drain
Bought a new battery from Costco this past February. Installed it without issue and used my Foxwell 530 to reset the alternator. I'm the second owner of the vehicle and was not aware of the fact that the vehicle never really sleeps and is continually drawing current unless you lock the vehicle which is kind of crazy since I park it in my garage.
What are you guys doing to prevent electrical draw on the battery while it's parked?
TIA for any tips
What are you guys doing to prevent electrical draw on the battery while it's parked?
TIA for any tips
Super Member
Joined: Dec 2015
Posts: 592
Likes: 233
From: Suburban Maryland
2023 E 450 Sedan. 2018 GLC 300. 2013 E 350 Coupe (retired)
First level is to keep key 30 or 40 feet away from the car, or place key in Faraday bag, and that also reduces the risk of theft. If you want more reduction in the cars electrical usage, turn off theft alarm functions. I hook up a trickle charger every few days to keep the battery topped off.
Last edited by smiles201; Apr 25, 2026 at 10:18 PM.
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Joined: Dec 2019
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Bought a new battery from Costco this past February. Installed it without issue and used my Foxwell 530 to reset the alternator. I'm the second owner of the vehicle and was not aware of the fact that the vehicle never really sleeps and is continually drawing current unless you lock the vehicle which is kind of crazy since I park it in my garage.
What are you guys doing to prevent electrical draw on the battery while it's parked?
TIA for any tips
What are you guys doing to prevent electrical draw on the battery while it's parked?
TIA for any tips
Member
Joined: Oct 2021
Posts: 76
Likes: 12
From: USA
2022 GLC 43 AMG SUV
As the OPs have already indicated, use a trickle charger if the car is not driven for more than 2 weeks. I use two trickle chargers (Motopower MP00205A, 12 V, 800 mA Automatic Battery Charger, Maintainer, Trickle Charger and Desulfator, $16.99 on Amazon) to keep the batteries in our two M-B cars at about 30 % SOC when we travel (I thought they would charge to ~100 %, but it's not the case.)
The alarm, the collision sensors and communications functions (remote access, over the air updates etc.) slowly drain the battery; one day I'm going to use a multimeter plugged in series in the 12 V battery circuit to measure the drain current when the car is locked.
The alarm, the collision sensors and communications functions (remote access, over the air updates etc.) slowly drain the battery; one day I'm going to use a multimeter plugged in series in the 12 V battery circuit to measure the drain current when the car is locked.
Last edited by TonyG3D; Apr 27, 2026 at 08:42 AM. Reason: text alignment
MBWorld Fanatic!
Joined: Oct 2019
Posts: 5,096
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From: Colorado
G550
30% SOC seems low -- a maintainer should be be keeping your battery much higher than that. If your battery is recently new, I'd buy a different charger. If you're measuring SOC at the jump terminals using a hadheld battery analyzer, check the battery diectly at its terminals.
Member
Joined: Oct 2021
Posts: 76
Likes: 12
From: USA
2022 GLC 43 AMG SUV
I agree; I was surprised myself.
To resolve this mystery, I'll use my Fluke multimeter inserted in series into the battery circuit and measure both the trickly charger and the drain current values--and post it here when ready.
To resolve this mystery, I'll use my Fluke multimeter inserted in series into the battery circuit and measure both the trickly charger and the drain current values--and post it here when ready.
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Out Of Control!!
Joined: Nov 2018
Posts: 11,311
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From: San Francisco Bay Area
2019 C63CS
I own a C63. Largely similar electrical architecture, except your GLC has MBUX and my C63 has COMAND 5.5. It is true that there's always a battery draw, but it's largely due to the online services that maintain a cellular connection and are always ready to respond to requests from the Mercedes me app. As mentioned above, Standby mode can be activated to turn off all consumers if the car is parked for an extended period. This will also tell you how long you can leave it that way. I get over 20 weeks if the battery is fully charged before turning on Standby mode. Keep in mind, it also turns off the alarm, as the alarm still drains the battery when the car is locked otherwise, so standby mode turns it all off to maximize the standby time.
I drive only about 4k miles per year, mostly weekends and sometimes it sits for several weeks. During the lockdowns I periodically put it on a trickle charger and I replaced the battery last year, but otherwise I don't do anything special. The new battery definitely holds the charge longer, though. My older trickle charger started to indicate that the battery was bad, which is what made me replace it. I only drove it 2 or three times over the last four weeks or so. I was away in Japan for two weeks and got back Sunday a week ago. Drove it once shortly after coming back, but it's been sitting unlocked in the garage since then and I just checked the battery in the Mercedes me app and it still shows it as fully charged. I had the car in standby mode while I was in Japan.
In my experience, locking the car or leaving it unlocked makes no difference. As said, if you lock it, then the armed alarm system uses battery. The key fobs themselves go to sleep after 2 minutes if they don't sense any motion, so there's no need for a faraday cage or keeping them far away from the car. Never been an issue for me.
I drive only about 4k miles per year, mostly weekends and sometimes it sits for several weeks. During the lockdowns I periodically put it on a trickle charger and I replaced the battery last year, but otherwise I don't do anything special. The new battery definitely holds the charge longer, though. My older trickle charger started to indicate that the battery was bad, which is what made me replace it. I only drove it 2 or three times over the last four weeks or so. I was away in Japan for two weeks and got back Sunday a week ago. Drove it once shortly after coming back, but it's been sitting unlocked in the garage since then and I just checked the battery in the Mercedes me app and it still shows it as fully charged. I had the car in standby mode while I was in Japan.
In my experience, locking the car or leaving it unlocked makes no difference. As said, if you lock it, then the armed alarm system uses battery. The key fobs themselves go to sleep after 2 minutes if they don't sense any motion, so there's no need for a faraday cage or keeping them far away from the car. Never been an issue for me.
Last edited by superswiss; Apr 27, 2026 at 05:19 PM.
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Thread Starter
Newbie
Joined: Jan 2026
Posts: 8
Likes: 0
From: North Cackalackey
2011 ML550, 2020 GL63 SUV
Thanks to everyone's suggestions.
I drive her 2 to 3 times a week and hook the battery charger/maintainer the other days of the week when she's idle.
As everyone alluded to the tech in the car can seemingly overwhelm the battery. I do like the simplicity of my ML550 but the GLC63 is light years ahead on multiple levels.
I drive her 2 to 3 times a week and hook the battery charger/maintainer the other days of the week when she's idle.
As everyone alluded to the tech in the car can seemingly overwhelm the battery. I do like the simplicity of my ML550 but the GLC63 is light years ahead on multiple levels.
