Hi everyone,

I’m reaching out to see if anyone else has experienced a recurring 12V battery issue with their 2022 GLE or has any advice on how to resolve this.

I first received a “battery low” warning last year and brought the car to the dealer. They checked it and said the battery was unhealthy, so they replaced it under warranty. However, the issue returned after only a few months.


Here’s my driving pattern:

• I drive the car about three times a week.

• Each drive is typically 1–2 hours long.



Despite this, the issue still persists. Here’s what happens:

1. After parking the car, I usually get a notification about the battery issue around six hours later via the app.

2. The next day, when I unlock the car, the alarm gets triggered.

I’m wondering if this could be due to something draining the battery while parked, or if it’s a deeper issue with the car’s electrical system. I’ve heard mixed things about parasitic drains and software updates being potential culprits.

Has anyone else experienced similar issues with the 12V battery? If so, how did you address it? I’d appreciate any insights or suggestions before I head back to the dealer again.

Thanks in advance for your help!

 

Assuming you haven't installed any aftermarket devices such as a dashcam or radar detector that was wired into an always hot circuit, there could be some OE device causing the problem. Contemporary cars never completely shut off, but after being parked for 10 minutes or so, the car should reduce its power consumption to less than 0.1 amperes. If you can afford to be without your car for a day, ask your dealer to monitor power consumption for several hours while it's parked. Alternately, you can buy a clamp-on DC ammeter (~$100) and do this yourself if you can access your battery without difficulty.

 

You have a defective battery. Take it in for replacement, there should be a percentage of warranty coverage if not the whole thing.

 

Sorry to read about your mixed ownership experience.
Your '22 GLE has a pronounced appetite for new batteries despite plenty of regular frequent long drives every week.

You landed the combination of "drained by driving" plus "drained by parking". This experience is neither new nor rare.
It can be dealt with in a few ways.

-- The first step will be to prevent high-speed limp modes.
Learn to setup display options to show voltage/current on instrument cluster while driving.
Youll be able to monitor the drained by drving below 12.0Volts >>> simply need to park and then restart car.


-- The core of this bug is built around marginal voltages that soft-crash CAN-Bus networking.
This is designed to be progressive by nature with different degrees involved from normal all the way to limp-mode cut-off.

The accelerated "drain while parked" is caused by chaos within CAN-B Modules. You have scored the express drain speed.

-- Let's scan your chassis to read faults for specific evidence

-- Use counter measures with a CTEK Charger plus portable jum-pack charger with the trunk 12V socket.

Based on your feedback we'll see what may help...
-- CAN-Bus issues ??
-- Soft-crashed: Reboots...
-- Stable CAN: ALT LIN!

New batteries don't fix this unless AGM has been toasted repeatedly by 90Amps

 

Thanks for your response! I did have a dashcam installed that takes power from the rain sensor. The dashcam has two modes: normal recording while driving and a timelapse mode during parking, which runs for a few hours before shutting off automatically.



Most of the time, it worked fine without issues. However, I noticed that during the instances when the battery drained quickly, the dashcam seemed to be recording as if the car was running (even though it wasn’t). To rule out the dashcam as the cause, I unplugged it on the first day the battery issue occurred.



As of now, I don’t have any other devices plugged into the car, but I’m wondering if the dashcam activity could provide a clue about what’s going on. Could it be related to the car not properly entering sleep mode?



Any insights would be greatly appreciated

 

Thanks for the detailed response! I’ve already purchased a jump starter and a battery maintainer as a precaution in case the car won’t start. However, I’ve noticed something peculiar: it seems like the car retains a small amount of power or possibly draws from the 48V system when the 12V battery is low.

For example, when I try to unlock the car with a low 12V battery, there’s a noticeable lag, and the alarm system is always triggered. This has been really awkward in public, as the alarm going off tends to draw attention.

I’m wondering if this behavior (pulling power from the 48V system) is intentional, or if it’s a sign of another issue with the car’s electrical systems. Could this be related to the CAN-Bus or a fault in the way the systems communicate during power deficiencies?

 

I am familiar with the embarrassment of alarm sounding after being disarmed successfully with the keyfob.
This examplify precisely the issue that's draining while parked: extra slow networking.
Unfortunately there's no one silver bullet hole to aim the parts-canon.

One of the body modules is causing this chaos. You may discover if a single module or more are causing this.

Do SCAN FOR HARD EVIDENCE. No sense in replacing good parts randomly.

These cars are built with multiple layers setup to interact under various conditions.

 

Dashcams that are motion activated can be a problem if they're constantly being triggered -- in a parking lot, for example, where there's always traffic and pedestrians. A 100 Ahr battery sounds large, but if you have a constant parasitic load connected that's drawing 500 mA, it will deplete the battery in about a week. Just a few days is enough to drop the charge to half that can compromise starting, and maybe affect other functions. Whether or not the camera is activating other systems when it triggers would require measuring the battery current draw, or maybe just watching the instrument panel activity to see if it illuminates.

 

Recommend getting a dashcam battery in that case.

 

Thanks for the insight! I actually don’t have the dashcam installed anymore, as I removed it last month to rule out any potential parasitic drain it might have been causing. However, the battery issue has still been happening over the past month, which makes me feel weird about the whole situation.

 

I still wonder if you may have damaged something during that dash cam installation, even though it's disconnected now.

I'm just going through installing one right now. I don't intend to use parking mode, so I don't need a battery or tap anything hot.

But I just don't think the wire gauges are up to my dash cam, which is a powerhog. It won't even operate with a standard USBC cable. Need one of those power USBCs.

Which makes me wonder if you overloaded your rain sensor wiring.

Was this battery drain concurrent with your first installation?

If you find your culprit.

 

That’s a good point, but the installation of the dashcam was quite simple, and it worked fine for the first year after I installed it. Even after the dealer replaced the battery, everything was fine for the first three months, so I don’t want to put the blame entirely on the dashcam.



I’m bringing the car back to the dealer tomorrow and hoping they can find the root cause of the issue. I’ll keep you posted on what they find!