W215 - Battery Drain. Or is it......?!

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SussexCL

Member
Joined
Sep 19, 2018
Messages
43
Location
West Sussex
Car
Mercedes CL600
You may have seen from my introductory post that my 2000 CL600 is new to me, just a month into ownership.

Now, in that month, I was on holiday for a fortnight, so we have about a week before, and a week after of experiential use.

The first week, the door locks were reluctant to lock, I thought it was the transmitter, and it turns out that indeed one of them does need new batteries, will sort this weekend, have already bought. Anyway week one, the car refused to start one morning, and a quick run on the trickle charger had it back to form. Of course I went on the forums, only to find a myriad of this and that battery drain problems.

Two week holiday, car is predictably flat as a pancake. Trickle charge, and recondition the battery.

This past week, the battery has barely been able to hold charge for more than two days. And then one day, she refused to start at the station, so I called the AA. One quick connection with their booster and it sprung to life. The ever helpful AA technician checked the flow of charge, and the alternator is doing its job. Then he checked the drain, and said that it was acceptable, bearing in mind that the car would not yet have gone to sleep. So I bought a new Varta Silver Series battery and replaced it last night. Will it last until the weekend, we will see!!

I guess the reason for the thread is to try and dispel some myths. I have seen suggestions as bizarre as turning your air conditioning and radio off before you switch the ignition off. Removing the CD shuttle from the disc changer. Hmmm, I cannot believe they suffered this problem from new, and am loathe to be dictated to by a recalcitrant car. The car has (dated) gadgets, and I want to use them. But as my station car, this needs to be reliable, and whilst I am not one of those 'throw eveything at it' people (previous owner spent £9k in four years), I am also not one of those 'run it on beer-tokens' people either. I love a challenge, and I especially love solving it. I would admit that electrics are not my forte, but hey, when better to learn.

A quick review of the forum had my battery replaced, and my PAS, ABS, and windows reset, so thank you for that.
 
The most common battery drain issues are the PSE pump in the boot and the command system.

You literally have to wait for everything to turn off to check the drain, it is a nightmare! I was lucky when in my w220 the command system caused a drain I just unplugged it and plugged it back in which somehow resolved the problem!
 
The most common battery drain issues are the PSE pump in the boot and the command system.

...I just unplugged it and plugged it back in which somehow resolved the problem!

Hmm, now you mention it,.... To be honest, after the second or third flat battery, every single 'odd' sound I hear, I think "could that be it". I remember a pump noise in that vicinity working, when I got it hooked up (with a flat battery) to a trickle charger, but that might well have been it re-pressurising the system. There's also a pump noise from the glovebox area, which might be,...the ABC pump?

Anyway, as of this morning, it seeeeeeeeems to be going okay, but we will see, the weekend of not being used, will be the big test. And then I can focus my attentions on the glovebox pump noise (have some CHF11s arriving in the post today!).
 
Don't ask me how or why but I had this problem also. So much so that on a trip to Rome one week-end I disconnected the battery whilst in the airport car park and reconnected it when we came back.

The problem had disappeared.
 
Glovebox noise will be your aircon fan... another very common problem! Check the drain on the passenger side of the engine bay against the bulk head isn’t full of water, if it is then water leaks down into the footwell doing damage to the electrics.
 
Don't ask me how or why but I had this problem also. So much so that on a trip to Rome one week-end I disconnected the battery whilst in the airport car park and reconnected it when we came back.

The problem had disappeared.
I always wondered how people left their W215's at the airport!!!

This whole 'Disconnect-reconnect' and 'turn it off-turn it on' is an odd theme that I seem to see arising in many threads on the W215!
 
Glovebox noise will be your aircon fan... another very common problem! Check the drain on the passenger side of the engine bay against the bulk head isn’t full of water, if it is then water leaks down into the footwell doing damage to the electrics.

Aha, thanks for that. I will definitely check it. The Aircon is currently showing the EC light on all the time, so something is amiss. Was recharged with coolant before I purchased, had just assumed I had a leak some where.

Great car, honest! Just suffering the effects of being used, after so many years of being kept unused in a garage.
 
I always wondered how people left their W215's at the airport!!!

This whole 'Disconnect-reconnect' and 'turn it off-turn it on' is an odd theme that I seem to see arising in many threads on the W215!
I don't do this any more...I was away for 10 days recently...and it started first time on return.
 
I don't do this any more...I was away for 10 days recently...and it started first time on return.
That's good to hear, would be the quickest way to put a dampner on a return from holiday! Used to have a similar problem with a London-street-parked Range Rover. Solution was to buy an absolute beast of an Optima battery. Never had a problem with starting after that.
 
Try this to reset the aircon light (same process in the w215 as w220), I think your noise is the fan which wouldn’t bring that light up.

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They are amazing cars, I’ve done around 150k miles in w215/w220s!!
 
Try this to reset the aircon light (same process in the w215 as w220), I think your noise is the fan which wouldn’t bring that light up.

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They are amazing cars, I’ve done around 150k miles in w215/w220s!!
Amazing, thanks for this, will try when I am home!
 
For those that followed this thread, it turned out to be TV Tuner and Alarm that refused to go to sleep. The alarm unit has been replaced, and the TV Tuner removed.

The car still eventually runs itself flat, after about 2-3 weeks of limited use. I am only using the car for a short drive into the station each day so guess that's what happens when you have the heater, heated seat and radio on, and limited recharge time in the car.

Am happy to trickle charge it every few weeks, and might buy one of those booster packs on the rare occasion that it gets too low to start.
 
Early CL's had an ABC control box that did not shut down properly when stopping the car,
getting out of it and then locking the doors.
It was necessary to lock the doors within a minute to make the control box shut down.
If not, it would stay "on" and then drain the battery.

Since Mercedes was late in adopting Flash memories, such a box has to be
replaced with a newer one, and then calibrated (correct level) using Star/Xentry.

Owners of early CL's experiencing "random" battery drain should check
the car's serial number in order to see if it is one of the affected vehicles.

It may, or may not be that 600's are affected. I have no longer any MB service
documents pertaining to my CL since they went with the car a few years ago
but the s/n information should be out there.
 
Early CL's had an ABC control box that did not shut down properly when stopping the car,
getting out of it and then locking the doors.
It was necessary to lock the doors within a minute to make the control box shut down.
If not, it would stay "on" and then drain the battery.

Since Mercedes was late in adopting Flash memories, such a box has to be
replaced with a newer one, and then calibrated (correct level) using Star/Xentry.

Owners of early CL's experiencing "random" battery drain should check
the car's serial number in order to see if it is one of the affected vehicles.

It may, or may not be that 600's are affected. I have no longer any MB service
documents pertaining to my CL since they went with the car a few years ago
but the s/n information should be out there.
Thanks, I had read of a myriad of different items that could prevent my car from going to sleep. I find myself having removed the satnav DVD, turning my AC and radio off, and trying, although not always possible, to lock the car within a minute of getting out. It does seem a bit of a palaver!

That said, it was a Mercedes Specialist who read the car with their STAR system who picked up the faults, so one assumes they might have identified the serial number. Mine is an early CL600. Any idea what I might best use in a search engine to source? Have had a few goes, to no avail. Thanks
 
(Found a note left in my server):

"On vehicles C215 s/n prior to 004585 and W220 s/n prior to 110219
the ABC control box has a software bug that causes the battery
to get discharged if the car is left unlocked for more than ~60 seconds after ignition
turn-off. The drain current is approximately 350mA. and it does not
take long to discharge the battery."


When checking for this, I purchased a DC current clamp meter.
There are a lot of such instruments, but few that could read currents
down to tenths of milliAmepers.

When performing the check, stop the car. Open the rear hatch
and "trick" the hatch into thinking it has been closed by manipulating
the lock mechanism.

Then remove the battery cover on the right side and clamp the meter
around one of the battery connections.

It think it will take some 20 minutes for all systems to go into sleep-mode
one by one. After one hour the current should be ... "low", in the order
of a few milliAmps. (Actually, I don't know since after I had the ABC control box
replaced the problem went away and I never had to worry about it anymore).

If the ABC-box is NOT the problem, and after having waited an hour or so
it should be quite easy to spot the problem by removing fuses one by one.

(And while you are near the hatch, have the registration plate illumination
checked. One common problem with old C215 is the 3rd brake light
gasket getting cracked by ageing causing water ingress into the lamps
and locking mechanism. The corrosion caused by this will blacken the covers.)

 
(Found a note left in my server):

"On vehicles C215 s/n prior to 004585 and W220 s/n prior to 110219
the ABC control box has a software bug that causes the battery
to get discharged if the car is left unlocked for more than ~60 seconds after ignition
turn-off. The drain current is approximately 350mA. and it does not
take long to discharge the battery."

Thanks very much for that, I will check the serial number when I get home tonight. Nice and easy, as from recollection it is there, in the windscreen!

In the meantime, I have bought myself a Genius Boost jump starter lest I find myself a few weeks down the line with a low battery and an urgent train to catch!!!
 

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