Lights are Turning On, Causing Battery to Die
Thread Starter
Newbie
Joined: Aug 2021
Posts: 2
Likes: 0
From: Chicago, USA
C300
Lights are Turning On, Causing Battery to Die
Hello Everyone,
I'm a new Mercedes owner and have been enjoying the car so far. I've done some electrical aesthetic modifications to the car. Before I go straight to the problem, I'll provide the list of mods that I first installed. I also attached links to each mod that I mentioned. Tonight I'll recharge the battery and see if I can replicate the issue and film the issue when it occurs.
Mods;
- Dash Cam Front & Rear (Hardwired to driver side fusebox)
- RGB DRL Lights (Hardwired to the main fusebox under the hood) (Ignition accessory fuse)
The Problem;
The issue came 3 months after I installed the RGB DRL lights. When I would turn off the car and lock, after about 10 minutes the DRL and star lights would turn on for about 40 minutes then shut-off. That has continued for about a week until one night it would not turn off leaving me a dead battery in the morning. I removed the DRL lights from the fusebox to see if the car would still drain the battery at night. It drained the battery two more times until the car stopped turning on the star when it was off and locked.
Solutions;
I have two solutions that I can do myself but I don't prefer.
1.) Connect the DRL lights to the battery directly (I hate this option as I have to manually turn off/on the lights every time I get in/out of the car.)
2.) Buy a second battery and connect to the alternator just like the cop cars have. (Complicated/expensive option, and so far no clue how to have the alternator power another battery)
3.) Ask the smart people on the MB Forums to see if there are any other solutions to this issue. (This is so far my favorite option)
Thanks!
I'm a new Mercedes owner and have been enjoying the car so far. I've done some electrical aesthetic modifications to the car. Before I go straight to the problem, I'll provide the list of mods that I first installed. I also attached links to each mod that I mentioned. Tonight I'll recharge the battery and see if I can replicate the issue and film the issue when it occurs.
Mods;
- Dash Cam Front & Rear (Hardwired to driver side fusebox)
- RGB DRL Lights (Hardwired to the main fusebox under the hood) (Ignition accessory fuse)
The Problem;
The issue came 3 months after I installed the RGB DRL lights. When I would turn off the car and lock, after about 10 minutes the DRL and star lights would turn on for about 40 minutes then shut-off. That has continued for about a week until one night it would not turn off leaving me a dead battery in the morning. I removed the DRL lights from the fusebox to see if the car would still drain the battery at night. It drained the battery two more times until the car stopped turning on the star when it was off and locked.
Solutions;
I have two solutions that I can do myself but I don't prefer.
1.) Connect the DRL lights to the battery directly (I hate this option as I have to manually turn off/on the lights every time I get in/out of the car.)
2.) Buy a second battery and connect to the alternator just like the cop cars have. (Complicated/expensive option, and so far no clue how to have the alternator power another battery)
3.) Ask the smart people on the MB Forums to see if there are any other solutions to this issue. (This is so far my favorite option)
Thanks!
Thread Starter
Newbie
Joined: Aug 2021
Posts: 2
Likes: 0
From: Chicago, USA
C300
I went to the dealer, they just want money. They didn't fix the problem. They just said, remove your mods and replaced the battery. That's not helpful if I want the problem fixed so the car doesn't drain and I keep my mods. I just have the FIX'd scanner but I bet that isn't sufficient.
MBWorld Fanatic!
Joined: May 2018
Posts: 1,434
Likes: 301
From: Illinois
2021 c300 Cab. Arrived 7/28/21 . 24 GLE 450e.
I went to the dealer, they just want money. They didn't fix the problem. They just said, remove your mods and replaced the battery. That's not helpful if I want the problem fixed so the car doesn't drain and I keep my mods. I just have the FIX'd scanner but I bet that isn't sufficient.
MBWorld Fanatic!
Joined: Nov 2003
Posts: 2,416
Likes: 498
From: Earth
2015 C300 4Matic Sport
This is the weirdest story ever. 
Things don't just turn on for no reason. You must've tapped the wrong fuse.
If the issue didn't stop after you removed the RGB DRL lights, then remove the other mods and check.
- You don't tap "a fuse box", you tap a specific fuse. Which ones did you use?
- There are plenty of fuses you should NOT tap. *Danger*
- There are fuses that only provide power only when the car is ON.
- There are fuses that only provide power 24/7.
Things don't just turn on for no reason. You must've tapped the wrong fuse.
If the issue didn't stop after you removed the RGB DRL lights, then remove the other mods and check.
Last edited by benzdude; Aug 27, 2021 at 11:46 PM.
