marchgroupinc

The 48 volt is basically the starter battery. The 12v battery is for accessories only. The two batteries are linked with converters 12v - 48v and 48v - 12V . When you put a 12v battery maintainer it also charges the 48v battery through the converter. I watch the partially charged status in the app and if it stays for a week I connect the 12v battery maintainer. I have one permanently installed now under the hood. The battery charging gage on the engine info screen shows the charge rate for the 12v system only. When it reads 12-12.8 volts I assume both the 48V and the 12 v are charged and when it reads 14.5- 14.8 one or both of the batteries are being charged. Some of the messages on the app like the one on the 12v battery being the starter battery are wrong. The 450 and the 580 do not have "starters" like the 12v kind most are familiar with. It has a ISG Integrated Starter Generator which is a multipurpose device that does all. It turns the engine to start and boosts the engine power with the 48V battery and also generates power to charge the 48v system.

Longroof45

Thank you. That's a great explanation. I thought perhaps the message on the app was wrong because when my 48V battery died, the app said the 12V battery was critical, when in fact it was the 48V. I just drove my car for 40 minutes (highway and city) and the app continues to say "partially charged". When you connect the battery maintainer, how long does it typically take to get the battery fully charged again? Also, we've had very cold temperatures in this area for several weeks. Do you think that alone could be enough to cause the "partially charged" condition?

marchgroupinc

Depends - 24- 36 hours . It is a 1.5A only without a smart charge. It puts 1.5A till it charges and then floats. Other "Smart" multi-stage chargers I tried get an error after 24 hours as it states there is a drain on the 12V while charging which of course is the MB internal converter charging the 48V battery at the same time. simple is better in this case.

zimirza2003

My 2020 GLS580 with 14,000 miles non start 3rd time and was towed to the dealer.
Last time they blame the terminals for the 24 V battery were painted over.
I am planing to take a cross country trip in couple of month with travel trailer in tow.
I don't know what to do with this issue, every time I start the car I hold my breath.
The problem is ....... this car drive so well, Emerald Green color looks fantastic.
This is my 8th Mercedes they have been extremely reliable one of then had 400K miles

E55Greasemonkey

Unfortunately the no-start condition has been plaguing this platform since it's release in 2019. Luckily, dealerships now have a lot of experience fixing these problems. Maybe the third time was the charm, as they say. Get familiar with MB's roadside service and whether or not they cover towing your trailer in case your one-sixty-lemon leaves you stranded again. Also be aware of how far the closest dealership is during your travels. I believe they still offer trip expense reimbursement for hotels stays, etc. due to breakdown. Bottom line is, have a plan just in case. That way if you do get stuck (again!) you're not caught in a panic and just go through the motions. This is what your warranty is for, but hopefully you won't need it on your trip.

Longroof45

Good advice. But why do you call it a one-sixty-lemon?

E55Greasemonkey

Because it rhymes with one-sixty-seven.
They also have the highest failure rate of any MB product built in the last few years along with many of them....more than any other recent model.... being bought back under U.S. lemon laws.

Longroof45

Ahhh, thank you for enlightening me.

mikapen

Well, Rhymin' Simon you're not.
It must be that your spell-check needs to relearn one-sixty-seven.

But I can't find any lemon law statistics without checking the very few States that post their Lemon Law statistics. Please help here with one of your sources,

If you're referring to Consumer Reports or JD Power, they only use W166 stats, and they are NOT reliability statistics, only questions about opinions on "satisfaction," which are driven by expectations.
ALL high-end models have higher expectations, with more discerning owners. KIA owners don't expect much of anything, and that's what they get, so their levels of satisfaction are high.

NHTSA does not agree with your claims, either.

zimirza2003

Got the car back from dealer after they disconnected the brake controller the non start issue went way. They claim the connector harness or the P2 controller was the culprit.
As I understand the controller circuit only gets activated when the 7-pin connecter in the back is hooked to the trailer. I am hoping this was the issue.
I will wait couple of months before I connect a new controller and harness prior to my trip in May this year

Thanks for the advice for traveling cross country with towing a trailer. I have traveled to Alaska by road from California towing my Airstream trailer with Mercedes GL350 Diesel without a hitch {figuratively}
Mercedes do not provide any info on towing a trailer e.g. connector harness or brake controller even though they have a towing package as an option. The dealers have no info on this topic either.
I did get lots of helpful info on this forum
Cheers

ricar61

According to roadside assistance, dealer will need 4 days to fix the issue. Frustrating after so many reports of the same issue …

E55Greasemonkey

9157

the problem is MBUSA’s fix is to reset the computer and send u on ur way. It’s happened to me twice and MBUSA has a “ could care less attitude”. If fact, they almost seem annoyed with the customer and have a total lack of concern….not the dealer but MBUSA itself.

Longroof45

I took my E450 wagon to the dealer today and they did a scan in response the the "patially charged" battery status that's been showing on my app for at least two weeks. The scan revealed "no faults" and "battery tests good at this time". However, the app continues to show "partially charged". The SA's only explanation for this was that the app is run by a third party. That battery as tested at the delaership is good. I have no explanation for the discrepancy.,

cguy450

Just saw this: https://www.globenewswire.com/news-r...-Firm-P-C.html

ricar61

Picking up the car, according to dealer, “all tests made, no need to replace the battery, software update executed”. They received the car this morning around 11AM, I’m picking up the car at 2:20PM……..

Md afzal

My b200 2015 shows the red sign stop vehicle check owners manual battery sign. What to do in this situation? New, need advise. Thanks

C200AMG2022

Last Friday I finally got my new C200 AMG delivered. I had to wait much longer then anticipated as it was promised to be delivered before 1 December 2021 for sure. As it was shipped 28 September from South Africa and arrived 22 October in Germany Bremerhaven, it should be easy to get to the Netherlands in that period of time. Unfortunately a chip appeared to be missing. But the waiting seemed to be worthwhile: what a beautiful car!
Until yesterday. after 123 km (I.e. 77 miles...) it refused to start. It showed a red battery error signal and then a yellow message saying 48 volt battery problem, please visit workshop (something similar in Dutch).
I contacted Mercedes-Benz services and they sent a truck to pick up my car. When it arrived, after approximately 30 minutes, it started again..
Earlier I also noticed some error messages, but these disappeared so I ignored those and also cannot recall them. Probably MB can find those in the logs.

Tomorrow I will drive to the dealership to have it checked.
I don't fully trust my new car anymore and my wife even refuses to drive it. A disappointing experience. I just hope it is software...and an update will solve all issues

W205C43PFL

We are sorry to hear that this has happened and what model year is your C-Class?

C200AMG2022

It is a W206, just delivered, brand new.

W205C43PFL

Truly sorry to hear that, I was hoping they have it fixed on the new C-Class. I am surprised and disappointed this problem since 2019 still exists on MB's newest car in 2022.
I hope your dealerships gets it solved swiftly so you are back on the road as soon as possible.

Longroof45

I'm sorry about your problem, but I can definitely relate. The 48 volt battery on my 2021 E450 wagon went bad within the first 200 miles, and then the replacement went bad around 500 miles later. Almost 5,000 miles later and battery no. 3 seems to have been the charm. The good news is that in the first 3 quarters of 2021, there were a lot more reports of failed batteries being replaced; but, unless I'm mistaken, the reports of failures have really died down, and more of the failures it seems are being corrected with software updates rather than with replacements. So the hope is that MB finally has their arms around the problem (they've certainly had enough experience with it even though they never formally issued a recall). It's also good news that, if you actually do need a battery replacement, it appears MB can can their hands on replacements pretty quickly now. Early on, especially here in the U.S., many had to wait for weeks until their local dealer could even get shipment of a replacement battery. Like you, I initially really lost confidence in my car and actually avoided one long trip that I had planned. Slowly my confidence is being restored. Let's hope for a quick and easy fix for your vehicle, maybe just a software update, so you can regain your love and confidence. One other reason to be hopeful is that you were able to re-start your car. That was not possible for me in the case of both of my failures -- so hopefully just software fo you.

C200AMG2022

Thanks for your empathetic response. Today the dealer informed me that the 48V error message is caused by a malfunctioning start button, and explains the errors. Replacement of the start button should solve the issue. It seems an acceptable explanation. And this seems to be a much less serious problem than perceived by most of the other people on this topic. Friday I expect my car to be repaired. So fingers crossed - I hope that is all it takes to solve the issue for once and all.

W205C43PFL

Seems like it is indeed happening on 2022 model year vehicles:
https://mbworld.org/forums/glc-class...ml#post8529649
Like forum member Longroof45 has stated, the fix needed would most likely be just a software to the battery control module as the defective batteries are no longer installed on the 2022 vehicles.

MuddyBlueJeans

Packed up, ready to go on a 10 Hour Rd. trip with the family for vacation and vehicle gave the 48V message, and vehicle will not start. Closest dealership there’s over 100 miles away and roadside assistance quoted me around $600 out of my pocket to pay for it because roadside assistance only covers up to 20 miles. Then call the dealership and they told me the battery is only covered for 24 months and my car is just over two years old with 39,000 miles. So looking at thousands of dollars to fix this issue (with the potential of issues, returning) on a car that’s less than three years old. It’s amazing that Mercedes is able to get away with this safety and reliability issue.