[markbenj]

Apologies for this long Post but it might be of help to others here with similar issues.

Some of you kind & helpful Folks might remember my recent Nightmare of 3 x ‘flat’ battery issues within a month, 3 x roadside rescue & jump starts, 2 x replacement new batteries 'dying' overnight, being effectively Grounded for 2 weeks during the Christmas & New Year hols etc. A truly frustrating experience after 6 years of reliable & trouble-free ownership of my otherwise immaculate 18 year-old W220.

Today: my local ‘wizard’ auto electrician spent a couple of hours THOROUGHLY investigating the root cause of the problem. After testing Current Draw (Milliamps) from the various complex electrical systems on my W220 when ‘Asleep’ (by ‘Asleep’ I mean the car, not him ), he narrowed the problem down to a faulty / ‘stuck’ manual boot (trunk) release button - which also has an electrical connection to the PSE system for the soft-close / locking feature. His Verdict? Maybe water ingress in the release button and / or due to its age. But, either way, it was keeping the PSE system ‘awake’ and draining the battery constantly 24/7 even with the ignition switched off and the car locked.

So… he disconnected the power supply from the ‘manual’ release button to the PSE system (after removing the boot-lid lining it took only 10 seconds) and HEY PRESTO!: Current Draw when the car is ‘asleep’ was about 50 milliamps - as it should be. With the boot release button re-connected temporarily: Current Draw was massively higher (about 3 Amps as I remember): which explained the almost overnight battery drain issue despite 3 perfectly healthy batteries.
Result: the car is mobile & reliable again - Hoorah!🕺 No anticipated further battery drain issues, the PSE works fine to auto lock / unlock the doors & boot etc remotely via the key fob.

So no further action needed unless for some reason I need / choose to replace the faulty ‘manual’ boot release button? I can live with that since the detachable blade key will still work if ever needed. 🤞

My Conclusion / Lesson(s) Learned?

1. I had mistakenly..🙄.. attributed the very first (OE spec) battery failure to it being 6 years-old and having ‘expired’ at the beginning of the recent Cold Snap here in the UK. BUT.. with hindsight it was almost certainly ‘False Logic’ on my part when the original battery was probably still perfectly healthy. (I like to think I know enough about car batteries to be careful with maintaining their health, i.e never run heavy drain electrical Auxiliaries - lights, wipers etc unless the engine is running).

2. Instead of ‘Jumping’ (ha ha) to the WRONG Conclusions and buying my way out-of the situation with TWO new batteries I SHOULD have had the Current Draw investigated FIRST. And.. it would have saved me a massive amount of Time, Hassle & Costs over the last month or so. $$$ £££ etc. Hey ho....

3. (As in my case..) if you don’t have the technical expertise & experience to thoroughly investigate & diagnose the root cause of a problem with your prized Mercedes (or your Dishwasher / Central Heating Boiler etc etc?), engage a Trusted / Recommended Expert to do it for you. It can often save Time, Money & Hassle in the long run.

To quote an old Saying: ‘A little Knowledge can be a Dangerous Thing’. Enough said?

Best wishes & thanks for your kind help & support on this excellent MB Forum. To be Continued…

MB

‘The Best or Nothing’

 

[Fancy321]

Good find! Like I said before, checking current drawn with a meter (I prefer a clamp-on meter) should provide a quick snapshot of the idle current.

 

[barnesandrewj]

Good find! Like I said before, checking current drawn with a meter (I prefer a clamp-on meter) should provide a quick snapshot of the idle current.

Great news Mark!

Guys I have an issue. Also battery drain. I woke up with flatish battery yesterday… think you jinxed me Mark! 😅
Saw signs with dash lights so did the one click and press reset button 3 times. Said 12,3 on dash but when I hit start it went down to 9 and just turned it over thank goodness.

-I got (as per Autel diag attached) error on CANBUS for Alarm System Level sensor 🤨
-I drove to dealer and tried to change the level sensor relay thinking it was best thing to change first. Still had the code. 🙏 Parts guy let me test it first at Benz dealer. So I’m looking for a second hand level sensor…. Went home and put her on charge all day.
-In the mean time now when I get out car the last thing I do is press the anti-tow button and it flashes red and I lock it. It’s meant to stop alarms from car tow/tilt…
I charged her full on CTek. Did full restore. She was on all 7 steps completed late last night and I unplugged her.
After issues experienced with my alarm siren I learned to check battery in am not by voltage but by plugging in Ctek next morning and she’d either go very quickly go through steps 1234 and just be on 4 and after 10mins go green which means checked to see it it’s holding charge not draining and it’s good to go. This am she went to 3 and stayed there doing bulk charging which took 2 hours and then to 4 and green, so she lost a few amp hours out of the 95….overnight.
Battery is still draining fast 🤨
Question - Will this error even though ignored by alarm now, still keep rear CANBUS alive thus draining the battery?!
Would greatly appreciate any feedback re that from anyone.
Regards and Thanks,
Andrew B

 

[markbenj]

Good find! Like I said before, checking current drawn with a meter (I prefer a clamp-on meter) should provide a quick snapshot of the idle current.

Thanks, good idea . That will be a useful piece of kit to have for any mystery battery drain problems in the future. And especially on an 18 year-old W220 with SO many complex electrics that can go 'rogue'! On balance I think I've been lucky that it's just the faulty boot (trunk) button when it could have been something far more involved, e.g. a waterlogged SAM etc? Fingers crossed... 🤞

 

[markbenj]

Great news Mark!

Guys I have an issue. Also battery drain. I woke up with flatish battery yesterday… think you jinxed me Mark! 😅
Saw signs with dash lights so did the one click and press reset button 3 times. Said 12,3 on dash but when I hit start it went down to 9 and just turned it over thank goodness.
View attachment 2801057
-I got (as per Autel diag attached) error on CANBUS for Alarm System Level sensor 🤨
-I drove to dealer and tried to change the level sensor relay thinking it was best thing to change first. Still had the code. 🙏 Parts guy let me test it first at Benz dealer. So I’m looking for a second hand level sensor…. Went home and put her on charge all day.
-In the mean time now when I get out car the last thing I do is press the anti-tow button and it flashes red and I lock it. It’s meant to stop alarms from car tow/tilt…
I charged her full on CTek. Did full restore. She was on all 7 steps completed late last night and I unplugged her.
After issues experienced with my alarm siren I learned to check battery in am not by voltage but by plugging in Ctek next morning and she’d either go very quickly go through steps 1234 and just be on 4 and after 10mins go green which means checked to see it it’s holding charge not draining and it’s good to go. This am she went to 3 and stayed there doing bulk charging which took 2 hours and then to 4 and green, so she lost a few amp hours out of the 95….overnight.
Battery is still draining fast 🤨
Question - Will this error even though ignored by alarm now, still keep rear CANBUS alive thus draining the battery?!
Would greatly appreciate any feedback re that from anyone.
Regards and Thanks,
Andrew B

Yikes Andrew! Maybe my W220 is talking to your W220 secretly and conspiring against us?

But seriously, I can't think of any other W220 forum where you would get more friendly & helpful technical support. Let us know how you get on and maybe (..?) re-post your story above as a New Post in case anyone hasn't followed my particular saga? I'll follow with interest and contribute if I can

 

[JC220]

Hi Mark,

I was wondering why no updates this week on one of the other threads!

First off glad to hear the issue was narrowed down to the microswitch on the boot lid. Good work! To me this is not an issue as you can use the release button inside the car or 99% of the time when you are approaching the car and need to open the boot then you have your remote key fob to do so. AKA in the real workd I never actually use the manual button on the boot lid in my w220s only in very limited circumstances do you need it.

For what its worth the boot latch mech from MB is only available as one complete assembly for £300 ish I checked this week. So your only option to repair is probably locating a good used handle and swap the whole thing out. I went to a breaker's yesterday and got a full good used latch and soft close mech for my S600 as it has an air leak somewhere in the boot mech.

The GOLDEN rule on S Classes electrical diagnoses is to NEVER say it is a success without giving it a couple of weeks

Also can I make a suggestion which I hope you can accept is meant to be respectful and helpful. Why so many new threads on this subject within a matter of days of eachother(?) It is bad forum etiquette to not complete threads with the solution as the next guy(s) coming behind will need to find ~6x threads of this issue to see how it was resolved.

I suggest mods combine all these recent threads into one thread.

 

[markbenj]

Thanks John, quite a relief to get this one fixed in a couple of hours after much hassle for a month!

I'd suspected the manual button & microswitch all along, but it was useful to have my local auto elec guy round just in case the drain was due to something else. He's tested various other systems and all appear to shut down ok, so hopefully the battery drain problem is solved... for now at least. 🤞

I agree about using the remote key fob or the switch in the driver's door (which work perfectly with the manual button microswitch isolated), so I guess I can effectively leave the button alone & not bother to replace it? And especially due to the cost - Yikes! My local Indie quoted a similar price + fitting costs for a new one last year but they were on back order from Germany at the time - hence the improvised repair.

Re. your suggestion about multiple Threads / same topic etc: yes that makes sense. It's just that some time ago when I posted about my (continuing - still unresolved) ADS Hard Damping issue, my threads turned into long running Epics with NO good news from me about a result - as I like to do if it helps others. I had the feeling that a few kind & helpful / expert contributors here had eventually lost interest in following them (no names mentioned). To be honest, I don't blame them . Hence 'New' / repeated Posts on the same topic - for better or worse..

The HD problem is still work in progress after eliminating many of the more likely / obvious causes despite the patient help & advice from members here, so I might revive it with a summary of all work / investigations done and an update soon. If I dare...

Either way, point taken graciously and I'll post here about any developments as appropriate.

Thanks again and 'to be continued'..

 

[markbenj]

Greetings All: Update 09/01/2023

I'm cautiously optimistic to have resolved my battery drain problem at long last (see above) 🤞. Thanks for your kind & helpful input .

As always: I try to give an accurate description of my (fortunately occasional) W220 fault symptoms - trivial or otherwise - with updates about progress or in an effort to share experiences and help other members in return.

I also appreciate that, sometimes, my (or other members'?) long-running 'Epic' Threads can cause a Headache for some of you here who generously offer your time, expert technical help & support but don't see any ++ results despite your best efforts. To be honest, I don't blame you if you 'Tune out / Unfollow' if & when your contributions aren't rewarded with a 'Good News' reply.

So, (Moderators!): can you please mark this Thread as 'Closed' for everyone's benefit. But I look forward to following, contributing and sharing input about other W220 Issues, as & when.

Many Thanks - and 'To be Continued'.

Mark B.

'The Best or Nothing'

 

[Witek_M]

So, I had this thought about linking all your battery trouble posts. Pointing do's and don'ts
Advice given vs advice ignored.

Then I realized that all my vehicles start on the first crank whenever I need them.

Wipe all your tears. 😷

 

[markbenj]

So, I had this thought about linking all your battery trouble posts. Pointing do's and don'ts
Advice given vs advice ignored.

Then I realized that all my vehicles start on the first crank whenever I need them.

Wipe all your tears. 😷

Thanks Witek M . The BDWTC (Battery Drain Woes Trauma Counselling) has worked well - with kind help from all here.

But seriously: on reflection, I should have had a possible parasitic battery drain issue investigated BEFORE I jumped to the conclusion that the original 6 year-old OE spec battery had simply died of 'old age' at the beginning of the UK cold snap and then wasted a lot of time & money with replacements / further SOS callouts etc over the following few weeks. Dugghhhh

At the time: because I'd never had a battery problem previously (in 6 years) I didn't even consider that the issue could be related to the simultaneous faulty boot (trunk) manual button / microswitch and a possible parasitic drain from it. Dugghhh again

On the ++ side: Problem solved (eventually..) and I've learned more about how, exactly, the various electrical modules work on our W220s - and what can happen when they go 'Rogue'. As my auto electrician said: it would have been MUCH more complicated & costly if one of the various ECUs / SAMs etc had been damaged due to water ingress / flooding in the floor-well of the car. Fortunately this wasn't the case, so I've got away lightly this time 🤞

Many thanks to you & others here for your kind help & support with my latest W220 issue.

Next... ?! 🤪

MB

 

[wallyp]

Have you reconsidered a STAR Diagnostic System?

 

[markbenj]

Have you reconsidered a STAR Diagnostic System?

I was wondering when you'd mention it AGAIN wally 😜😊. But seriously, Yep, as I intend to keep the car long term I'll start doing some serious research into it. I might need some guidance though...

 

[cowboyt]

We'll give it another week or so just to make sure, and if it's still solved, sure, I can close it if you want.

 

[Witek_M]

Thanks Witek M . The BDWTC (Battery Drain Woes Trauma Counselling) has worked well - with kind help from all here.

But seriously: on reflection, I should have had a possible parasitic battery drain issue investigated BEFORE I jumped to the conclusion that the original 6 year-old OE spec battery had simply died of 'old age' at the beginning of the UK cold snap and then wasted a lot of time & money with replacements / further SOS callouts etc over the following few weeks. Dugghhhh

At the time: because I'd never had a battery problem previously (in 6 years) I didn't even consider that the issue could be related to the simultaneous faulty boot (trunk) manual button / microswitch and a possible parasitic drain from it. Dugghhh again

On the ++ side: Problem solved (eventually..) and I've learned more about how, exactly, the various electrical modules work on our W220s - and what can happen when they go 'Rogue'. As my auto electrician said: it would have been MUCH more complicated & costly if one of the various ECUs / SAMs etc had been damaged due to water ingress / flooding in the floor-well of the car. Fortunately this wasn't the case, so I've got away lightly this time 🤞

Many thanks to you & others here for your kind help & support with my latest W220 issue.

Next... ?! 🤪

MB

Have you followed my advice about getting battery monitor you would have saved yourself two events of getting stranded. One look at battery monitor voltage slope would have warned you that there is something big draining battery. At that time only solution would be to disconnect it. You were not in position for anything else.

 

[Witek_M]

Here are couple of screenshots from battery monitor. Battery before charging 12.51V, then on CTEK until complete cycle. About 5 hours. Then 6 days at rest. That vehicle has zero parasitic consumption. I pulled fuse for the clock 20 years ago.

 

[markbenj]

Here are couple of screenshots from battery monitor. Battery before charging 12.51V, then on CTEK until complete cycle. About 5 hours. Then 6 days at rest. That vehicle has zero parasitic consumption. I pulled fuse for the clock 20 years ago.

Wow, Thanks again! That looks like a really useful bit of kit. Can you give me some more details on your particular CTEK monitor (model / spec etc)? If not horrendously priced, I'll buy one and it could save me a LOT of battery drain headaches in the future - especially when (about once per month) the car is unused & 'asleep' for a few days. .

 

[Witek_M]

Wow, Thanks again! That looks like a really useful bit of kit. Can you give me some more details on your particular CTEK monitor (model / spec etc)? If not horrendously priced, I'll buy one and it could save me a LOT of battery drain headaches in the future - especially when (about once per month) the car is unused & 'asleep' for a few days. .

It is CTEK MXS 5.0.

Amazon.com: CTEK - 40-206 MXS 5.0 Fully Automatic 4.3 amp Battery Charger and Maintainer 12V : Automotive

Buy CTEK - 40-206 MXS 5.0 Fully Automatic 4.3 amp Battery Charger and Maintainer 12V: Battery Chargers - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

MXS 5.0 UK

56-975

www.ctek.com

 

[markbenj]

It is CTEK MXS 5.0.

Amazon.com: CTEK - 40-206 MXS 5.0 Fully Automatic 4.3 amp Battery Charger and Maintainer 12V : Automotive

Buy CTEK - 40-206 MXS 5.0 Fully Automatic 4.3 amp Battery Charger and Maintainer 12V: Battery Chargers - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

MXS 5.0 UK

56-975

www.ctek.com

Great, thanks!

 

[barnesandrewj]

What I use too Mark! That model as been out for years and still being sold. A great product.

 

[markbenj]

What I use too Mark! That model as been out for years and still being sold. A great product.

(Sorry for my late reply - I din't see until today!)