I have a 2021 Mercedes GLC 300 with around 40k miles. Within approx the last 8 months it’s been giving me email/text alerts that the starter battery is critically low. These alerts are confirmed by a warning on the actual dashboard of the car.

I keep it in an attached garage. It never goes more than 2d without being driven. I take it in for all regular maintenance etc.

It’s been to the dealer 3 times and they keep saying “the battery is fine.”

I got the battery alert twice today despite driving an hour continuously.

It’s going back to the dealer tomorrow.

Anyone else experience this or have thoughts? Is the dealer dragging their feet on a battery replacement since this is still under warranty? Is it a software issue?

I work 30-40 min from my hometown so don’t relish the thought of being caught with a potential dead battery.

 

I had same problem with my 2020. Solution was to replace the battery. I turned the lease in 3 yrs later and if the warning came on it went away after a short drive. It might have happened 2-3 time at the most. My 2023 has had battery alert 2 time One because I had he accessories running for a long time , my fault. The other time don’t know why. But drove to store and back hasn’t happened again.

You under still under warranty. Change the battery and check all connections by hand not their PC.

By the way you posted to the new GLC300 site X254 you want the X253.

 

This warning is somewhat conservative, but it shouldn't happen if the car is driven regularly. For comparison, I drive my 2019 C63 mostly on weekends. Just did the mileage calculation for last year and it came out to 4200 miles, so about 80 miles per week on average and that's mostly done on weekends w/ a couple of longer trips in between. I've only gotten this alert when the car was in for service and they were working on it for several days with doors open and such. Got it the first time when I had PPF installed after taking delivery. They were working on it for 3 days with doors open I assume and on the third day I started to get the alert. It has happened a few more times when the car was in for service. Since I drive it very little, I now hook it up to the battery tender the day before service if in the app the battery charge shows as "Partially charged" to make sure it goes in with a fully charged battery. That has mostly avoided these alerts.

Unfortunately, getting the battery replaced has become really difficult. I talked with my SA about it. They have to subject it to a very specific test from MB and they are only allowed to replace the battery if it fails this test. He told me that they had cars towed in with flat batteries that would still pass the test, so they couldn't do anything other than to send the customers on their way with a fully charged battery.

The thing to be aware of is that these cars constantly draw down the battery, because they keep the cellular connection active. One possibility is that if you have a really bad cell signal where the car is parked, then it could draw down the battery quicker as it needs to boost the signal. Just like a cellphone burns through the battery quicker in low coverage/no coverage areas. One way to avoid that is using the standby mode, which turns off all the consumers and shows for how long you can leave the car parked. As shown in the picture below, I get 21 weeks in standby mode with a full battery. See what yours says. It's a good way to judge your battery. If it's low then you will only get a few weeks or it may even say that standby mode is not available, because the charge of the battery is too low. FYI...standby mode also turns off the alarm, so might not wanna use it unless the car is parked in a private and secure garage.

Some people may also give you the advise to make sure the car is locked when parked, but that doesn't make a difference. I always park my car unlocked in my garage, and the key fobs now have a motion sensor that puts them to sleep after 2 minutes if they are not being moved.

 

I had this issue on my 2023 GLC 300 in Australia. The dealer said there is a bug that causes the 12V battery to do this if you lock the car more than once - e.g. lock it again with the key when it is already locked. I stopped doing this - was doing it sometimes by habit to ensure door was locked - and the issues has not come back. They said the bug will be resolved in the next update Feb/March.

 

Thank you superswiss for your very much appreciated information. Surprising that the battery information for your 2019 holds true for my 2023 GLC. I had thought it was a new problem just for the x254 cars. I hope MB clears this up soon. It is not something one should have to worry about with a new car. Here are some screen shots for activating the standby mode. Your 21 week activation is surprising. The most I have been able to get is 12 but still a good length.
Screenshots are in reverse order.

 

You are on the wrong forum

 

Yes, I know that asu224 started this thread in the wrong forum but I thought superswiss’s post was so good that I wanted to add to it.

 

Mine has killed its second battery in less than 5 years. Yours is doing better than mine.

 

Mine has just come back from the dealer with a replaced battery. '23 GLC300e - a little more than 2 year old car. The same "critical starter battery issue" message came up a couple of times, didn't think anything of it. Then 2 weeks ago, the car was fully charged in the evening, but was about 80% charged in the morning and some sort of fan was activated inside. The interior was noticeably hot.
The dealer told us that the EV battery kept trying to charge the 12V battery, hence the depletion and the battery cooling fan being on the entire night.