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last winter I ended up having to park the car a few days here and there due to rather nasty road conditions so I connected it to my charger and it always charged it up to the max. I got an alert a couple days ago indicating the battery is a bit low as I'm not driving quite as far for work anymore as I did so I brought out my charger, connected it and expected it to be all charged up in the morning. It only will go up to the 3rd light (previously all were lit up) . . . does that mean the battery has reached its end of life? I had it replaced I believe 2 or 3 years ago but it seems it should last a bit longer than that. Maybe not . . . ?
As a rule of thumb your battery charger should be 10% - 20% of the Ah rating of the battery. E.g A 100Ah battery would require a 10 Amp charger as a minimum. Since E63 batteries are 90-95Ah, you need a 10amp charger or so, so leaving it on the charger longer may fix your problem, depending upon how discharged the battery is
But since we’re on the topic, i changed my battery (Diehard AGM) in February 2024 after getting the 12v battery low warnings and the ominous “starter batter critical” warnings. All was fine until i was washing the wheels outside, doors locked, and got the battery low warning again. When I’m not using the car, I have it connected to a Deltran tender, 1.5amps. I have quick connects to the battery, hooked up to + and - terminals. I’ve since learned the 1.5amp is woefully underpowered for these batteries and since bought an 8 amp tender. I also changed the battery again, and reconnected the quick connects so the negative connection is down stream of the battery management sensor. Too much time on You Tube taught me if you connect to the negative terminal, the battery sensor is not getting accurate information about the charging. So I connected to the Etorx bolt that holds the sensor to the negative battery wire. Fingers crossed (also changed the voltage converter since that should be done with a battery change
Anyone have any other ideas to preserve battery life? Are these cars just overly sensitive to discharged batteries?
I find the battery warning to be conservative. I get the warning if the electronics stay on long like after washing the car, applying ceramic spray, and then cleaning the interior. When measuring the voltage after getting the warning, it’s still over 12.2V which is still plenty of charge for an AGM battery to start the car.
Also make sure your battery actually is AGM. I don't believe W212 pre-facelifts were AGM (not an expert, but my 2018 wagon was regular lead-acid battery so imagine your 2019 is as well).
Also, once a year, put the battery into Recondition mode (make sure AGM is also appropriately selected if needed). CTEK advised once a year reconditioning measurably improves the battery. (I put a calendar item on my iPhone for each vehicle).
I had this same question when I got my first battery warning. The standard ctek takes a while to get up through its stages on the w213 battery. At the time a forum member suggested I get the bigger ctek, which I did...and it does work significantly faster. This is the one:
Yeah, that was kinda weird. I just pointed out the factory recommends shutting down comms via standby mode if the car sits for an extended period of time to minimize battery drain, and an odd "prove it" response resulted. Hey, take it up with Mercedes.
There is a best practices method for battery charging. Do you mind if I ask what steps you take to charge it?
Nothing special as long as you use a modern AGM charger. The CTEK chargers are very smart and run through the various stages of charging an AGM battery. Phase 1: desulfation via pulsed current and voltage; phase 2: detection of dead battery and possible abort; phase 3: bulk charge with maximum current to 80% capacity; phase 4: absorption by charging with constant voltage and declining current; phase 5: analysis by applying load and seeing if battery can hold charge; phase 6: recondition, if selected, charger applies increasing voltage to battery to encourage outgassing; phase 7: float, maintain charge with constant voltage; and phase 8: maintains full charge with periodic pulse of voltage.
This is why CTEKs are worth their weight in gold. No cheap charger will do this.
Nothing special as long as you use a modern AGM charger. The CTEK chargers are very smart and run through the various stages of charging an AGM battery. Phase 1: desulfation via pulsed current and voltage; phase 2: detection of dead battery and possible abort; phase 3: bulk charge with maximum current to 80% capacity; phase 4: absorption by charging with constant voltage and declining current; phase 5: analysis by applying load and seeing if battery can hold charge; phase 6: recondition, if selected, charger applies increasing voltage to battery to encourage outgassing; phase 7: float, maintain charge with constant voltage; and phase 8: maintains full charge with periodic pulse of voltage.
This is why CTEKs are worth their weight in gold. No cheap charger will do this.
CTEK provides various dongles with each charger. I always permanently install a dongle that has ring lugs at one end (to connect to the positive and negative battery terminals) and a quick disconnect (with a tethered removable rubber cover), which easily attaches to a matching connector on the charger end. I have a 300SL with the battery in the back, so I pop the trunk to access. My E63s wagon has the battery in the front right next to the firewall. The ring lugged dongle takes a bit to install, but is fantastic for all the models where the battery is enclosed and not easily accessible.
You can also clip on standard clamps, but those pop off and often interfere with closing the hood.
Pop the hood, connect, close hood (almost all the way!). I cover my car and the slightly open hood does not interfere with cover fit.
Me neither, just use the red + and brass stud. I rarely need to top off the battery, and even without topoff the battery has never failed to start the engine when the battery level low or critical appears.
07-12-2024, 11:39 AM
