b0rderman

Is there a trick to topping off the batteries on our car? I had the car off, in park, locked and hooked up to two different CTEK tenders under the hood. Both CTEKs behave in the same way, they "light up" to step 2, and then proceed to get very hot over the course of 5-10 minutes. The CTEKs never progress to step 3.

onesixeight

What model CTEK are you using? I'm using CTEK 7002-US and it works just fine with my S213 E63

I installed the the quick connect directly to the battery but previous to that, I used the jump points on the right side of the engine without issue.

I noticed on my E63, I often get the starter battery drained message if I don't drive the car for a while.

whoover

Stage two on mine can take (according to the manual that came with it) up to 8 hours to complete. The fact that it's hot means it's charging the battery. The fact that it's still in stage 2 means it hasn't gotten to 12.6 volts yet. A complete charge, until all lights are on, can take up to 48 hours. The electrical system of these cars doesn't come close to fully charging these batteries.

Once you get it fully charged, using the charger once a week or so will go much faster.

Pikapan

Depends on which model CTEK charger he has. I have the 5.0 and it has LEDs for 8 steps. It should progress to step 3 usually within 5 minutes of hooking up as the first 2 steps are actually just testing whether or not the battery is able to hold a charge. Step 3 is when it actually starts charging.

MuffinFlavored

I actually have an even weirder problem semi-related.

My car, *while running* or while off says the battery is giving 3 volts.

I confirmed the OBD-II port isn't fault because I stuck a 12v power supply and everything came up 12v.

Even with my car on one of those Amazon battery power car booster things, my car was reading 3v.

I gotta try with my friend's car on jumper wires to see what's up. I know one day I was doing CAN stuff and I drained my battery all the way dead. Maybe that's the root cause?

whoover

Look in the manual, page 11. The last row says "Max 8 h" under step 2. It's applying 4.3A to bring the battery voltage to 12.6. If the battery is fairly well charged, that will be quick. If it's fairly discharged, it can take a while (hours). If after 8 hours the battery hasn't accepted 12.6, it's determined to be toast. Yours and mine move to step 3 quickly because the batteries are in a good state of charge, but a run-down (but serviceable) battery can take much longer.

MuffinFlavored

would just driving around not recharge the battery? how many amps does the alternator deliver to the battery?

whoover

Many owners have observed that the charging system does not fully charge these batteries. Nobody is quite sure why, but even a long highway drive won't take the battery close to its fully-charged voltage. There's plenty of amps but it cuts charging at a much lower voltage than the AGM float level of 13.6v. That means that, with all the electrical consumers this car has, a few days of around-town driving will result in partial-charge alerts from Mercedes Me. Letting the CTEK take it to float every week or two avoids this.

b0rderman

Yes I’ve got the MXS 5.0. I also have a 4.3. They both just camped out at step 2.

I am trying again today with the 5.0 to see how brave I can be with the hot brick. Instant update: after driving around last night for 30 minutes, and hooking the CTEK 5.0 up this morning the charger went to step 3 after only 15 minutes. This is what I was used to see happening, with little heat in the brick. Thanks for the help Whoover.

In regard to how the battery could get like this...90% of my trips are under two miles: work, grocery, beach, etc.

What I believe is also compounding the problem is I have been leaving the car unlocked in the garage when getting home from work late (to avoid the honk and dogs barking and baby waking up). Yesterday I took the monumental action of silencing the lock so the car will sit locked overnight and hopefully that results in less parasitic draw.

whoover

I know people have said that locking the car makes a difference, but I'm skeptical. I can't think of any electrical consumers that would be switched off by locking the car.

6G Schnell

Driving around will recharge the battery, if you are ready to drive for more than 100 miles. Recent example: started with battery at “critical”, after 100+ miles improved to “partially charged” the next stop was 300 miles of driving around and finally improved to “battery charged”.

CTEK is better ROI, as price is less than the price of gas needed to recharge. Have two different CTEK chargers, and yes, it can take over 24 hours to recharge the battery. Depends on the output current (7A charger will take less time than 4A-rated).

There must be design flaw with w213 electrical system. Could be the both charging and battery capacity under designed. Search the forum, there have been plenty of battery - related issues.

Have never experienced any battery issues with W212, or any other car/make in the past....

6G Schnell

CTEK 7002 will charge faster.

Locking the car does not make any difference.

b0rderman

Good to know the 7002, thanks.

You know for sure that an unlocked W213 drains the battery equally the same as a locked W213 over the course of several days?

whoover

Nobody can say anything for sure with these complicated cars, but nobody has ever explained why it would matter. For instance, one of the biggest users of power in a sitting car is the Mercedes Me radio communications that monitors whether the car is locked. Obviously, it's going to be on whether the car is locked or not. In fact, it's this radio communications system that standby mode turns off. Older models would stay awake talking to a key left inside the car, so they told you to not store the key in the car overnight. This might have been interpreted as lock the car to save power, but it doesn't apply to our cars. Our keys go to sleep after a few minutes of not being moved. This is better both for security and power consumption. For our cars, I think it's an old wives tale.

b0rderman

Fair enough...all the systems in a car make a racket in a quiet garage when the thing is supposedly off.

6G Schnell

Don't have any measurements to show, but I never lock the car in my garage and have not noticed any battery drainage. Doors not locked, but closed.

And one more observation: while cleaning the leather interior and just opening/closing the doors battery went from Charged to Partial...

E634Me

Agree with earlier comments that this is the most busy car when turned off that I've ever had.

My 4 mile round trip to work and back wasn't enough to keep the battery charged enough to keep the auto stop/start feature active. A 50+ mile round trip generally was enough to get it working again for a couple of days. When I brought my car in for some other service they did a diagnostic on the battery and found that it wan't up to par and replaced it.

It's been working OK since then. One other thing that exacerbates the issue I'm sure is that I travel frequently for a week here and a couple weeks there. Generally I haven't put the car on a charger but doing so on the previous battery was enough to reenable the auto start/stop feature for a couple days.

I have a couple of chargers but the one that seemed to work best is the Optima battery charger. I purchased that because I had Optima batteries in my truck for a while (not happy with them). Pretty versatile charger that will bring up a fairly dead battery where a battery tender doesn't sense enough voltage to kick in.

Fingers crossed that the new battery hangs in there longer than the original factory battery.

6G Schnell

Would be nice to agree on what we are agreeing on. May we ask what is definition of "car turned off"?
Car turned off may have light on, radio playing, etc.....

E634Me

Ignition and accessories cut off. Pulled into the garage, put into park, and engine ignition button pressed to turn off the car. Basically like turning off the car and removing the key in old school cars.

6G Schnell

Thanks, this helps. I would also add taking the key inside the house.
Under these conditions I have never noticed any battery drainage. And over extended time period.

Don’t believe there is any significant current draw due to “Mercedes me” communicating with the mother ship.

However, if somebody on this board has solid data and measurements, please speak up and educate us.

whoover

From the manual: standby mode (to extend battery life when the car is not used) functions by suspending communications with Mercedes Me ("online services"). It's the predominant current draw for a parked car.

6G Schnell

Thanks for the effort, my friend. This qualitative statement speaks about Standby mode only.

Question is for specific scenario: ignition off, etc. as defined already.We had the same discussion last year and still no real answer.

I asked the simple technical question while back: is the current draw in microA, or mA, or something else?

Was hoping to get a quantitative answer in Amps, Watts, or whatever is available.
Can somebody help us out with this piece of data?

b0rderman

If that isn't 6G volunteering himself...

whoover

Not sure what your second sentence means. I was disputing your statement that the Mercedes Me communications isn't significant when looking at battery draw-down. It is the most significant and is why there is a way to turn it off to extend battery charge life. It speaks about Standby mode because that's the way to address current draw when the car is parked, which is what I thought the topic was.

As to specific current, it will fluctuate as the car makes calls or responds to calls from the server. If Mercedes Me decides to upload a new version of the Hermes software to the car (as all of ours did last year) it will use a lot more power than when it's just listening for calls. Furthermore, just as with your cell phone, the resting current draw can vary by a factor of ten depending on how easy it is for the Hermes module to communicate with a cell tower. Distance from the tower can require the radio to switch to a higher-power mode. For these reasons it's impossible to quote a single current draw, like you could if you were talking about a single light bulb. But considering that MB recommend you switch this communications off if the car will be idle for two weeks or more, we can conclude the average draw of the communications with online services would be measured in hundreds of milliamps. 100 mA would drain the battery by about 2 Ah a day.

6G Schnell

Well, this thread is getting more complicated than what is needed:
1. Stand by was not the question here, so why would we introduce a new variable we know nothing about?
2. General description of what might be going on with communication module does not help. And BTW, there are 24 hours in a day, not 20.
3. Not sure why are we going in circles instead of getting the actual technical data?

Let me clarify, just in case. We need a single number, or a range to answer what is the current drain for the specific scenario we defined.
Every piece of electronics/communication equipment has quite a few specs about current and power consumption:
IccMAX, PowerMAX, Icc standby, Power standby and so on...

Lots of folks here have access to the relevant documentation. Please speak up......