Hey guys,

This is weird. Dealer put in a new battery under warranty about 2 weeks ago. I have been noticing that it doesn’t start with the normal energy. A bit slow. Today in the garage I noticed that the radio would shut off without the engine running after only 5 seconds or so. Normally that happens after 15 minutes at least. So then when I went to start the car, it would barely turn over and not fire up. Then the hands on the servo controlled clock started spinning around. All typical of power loss, ie: dead battery. I put my trickle charger/starter on her for 5 minutes and she started.

After she started, I disconnected the charger and checked terminal voltage with my multi-meter. I was getting consistent 14.3 volts while at idle. I was getting 12.8 with engine off. This tells me the alternator is working. Soooooo. Hmmmmmm. WTH is going on here?

I am wondering if when you get a battery replaced under warranty, maybe it is not a brand new battery? Maybe some reconditioned battery? Because it sure seems like they replaced a bad battery with another bad battery.

Oh, btw, I popped the blower box off above the battery to make sure they did replace it. It looked new and had “12/18” round sticker on it.

Any guesses?

yes they use brand new batteries

likely if not a fluke bad battery, there is something overdrawing the current while the car is off ....

https://mbworld.org/forums/w212-amg/...-question.html

Let the battery sit overnight and then check the voltage without starting the motor.
On rare occasions new batteries are not good.

Thanks for both replies. I actually was thinking about a drain also and forgot to mention it. So I was thinking maybe my alpine sub amp wasnt shutting off. So I checked it and is working properly.

Another interesting coincidence is that these battery issues started after 2 significant events that it went to the dealer for both. Left rear body damage from getting rear ended where the radar sensors were replaced for lane assist, AAAAND, the brand new motor being installed. Perhaps something is not properly connected in the various harnesses. Seems unlikely. But sure is quite a coincidence.

Good idea to check base battery voltage after sitting for some time. I will do that tomorrow. Maybe a weak cell in it.

Thanks Again. Merry Xmas!

First, Merry Christmas to everyone!

Looks like the mystery is solved. After being on the charger yesterday for hours and the charger saying “charged”, the battery was dead this morning. Nothing was left on. The car wasnt even driven after being charged.

But the BIG tell was the battery voltage this morning. 10.7 volts! Looks a lot like a dead cell. Looks like I will be having MB bring me a new battery tomorrow.

yes, it's cheaper than towing it and it's covered under mbcare or whatever it is called

the other thought is charging this battery then disconnecting it from the car and seeing if it maintains the charge without any current draw from the e63

Your other thought is not exactly correct. Reason being that a battery should never read below 12 volts even when drained. This only happens when a cell is dead within the battery. Drained batteries will still read 12+ volts. Also, the car almost starts at only 10 volts. This suggests the other cells are charged.

Regarding remote install of the battery, they really do do it. They put a new battery in my 2011 about 4 years ago right in my garage.

Negative terminal was disconnected. Therefore no load. With no load the batter was at 10.5/10,7 volts. From experience working as a mechanic many years ago putting myself through college, this is indicative of 1 bad cell within the battery. As I recall there are 6 cells within the battery casing. When this was seen, we ALWAYS replaced the battery.

I respect your experience and measurements. However, I have never seen a salvageable battery with no load reading in the 10+volt range. Also, this car and battery are in 60 degree weather here in N California.

Pretty confident here that the battery will be replaced tomorrow and be the end of it.

So today, after all the great things MB has done for me, they dropped the ball pretty hard. Roadside service basically told me that no local dealerships offer roadside assistance any longer including my dealership that performed a battery swap 4 years ago in my garage. They said that I could call my SA and they sometimes will make exceptions and send out a tech, but that she cannot dispatch one. So I tried that but my SA is out this week for the holidays. I then tried to reach an alternate SA and failed to get anyone. Roadside said they could dispatch a tow truck to take my car to the dealer. Uh, no thanks. Might sit there until next week over a battery and my clear bra installation is happening tomorrow.

At this point I just went and bought a new battery and installed it in about 10 minutes. All is fine and working correctly now. The parts place actually told me they would take the battery back within 2 weeks if the dealer gives me a replacement. So thats actually better customer service than MB gave me today. I am trying to cut them somewhat of a break as the holidays do create logistic issues. Too bad cars don’t understand not to breakdown at Christmas. Lol

I did run one interesting test today. I connected my multi meter in series with one of the terminals disconnected in current measuring mode. I believe everything was off, and yet I was seeing a 7.5 amp draw. Hmmm. Thats apx 90 watts. That seems high to me. Maybe something was active though as not long before that I was trying to start the car without success. The old/new battery was shot for sure though as after an hour on the charger out of the car, it was still only giving 10.5 volts.

Anybody know (as in not speculating) if a 7 amp draw is normal. Seems high to me.

Thanks

That doesn't seem normal

That's like running an upright vacuum constantly off your battery


I take it the car was quiet .. meaning no fans or airmatic working .. the electronics would never draw 7amps

Are these car ever quiet? Mine makes all kinds of noises if I even glance in it's general direction!

So the car was left alone in the garage for about15 hours before I started it this morning. I imagine that if the car actually had a constant 7 amp draw for 15 hours it would either not start or barely start. But, it started right up quite strong. I believe something was running somewhere when did my current draw test. For batteries, it really comes down to duty cycle (% of time under load). So a constant 7 amp draw would be a 100% duty cycle at 7 amps. My guess, as we all know how active various systems are on these cars even while parked, is that the 7 amp draw stopped after things settled down.

I just cant believe it would have started so strong this morning otherwise.

As a side note: She was successfully delivered to the tint shop for Suntek clear bra and front door window tinting this morning! Picking her up in about 6 hours.