Slow battery drain (car won't go to sleep)
 

Since I got the car it has a known slow drain on the battery.

A recent observation: With the car locked and inside my garage, if I touch any of the left door handles, the instrument cluster lights up, and goes out again after about 60 seconds. (I can't check this on the right door handles, the car is parked too close to the wall).

When this happens, the battery voltage drops from say 12.50 V about 0.3 V, and recovers after the cluster goes out again (no charger connected).

I installed some time ago an intelligent C-TEK charger to the battery terminals (with a plug outside of the right tail light) - this takes care to keep the battery maintained without opening the trunk.

What's going on here? Is this normal? Any ideas or suggestions?

thnx

How old is your battery?

do you have keyless entry?

A bit over a year

Yeas, and I keep the keycard far away!

kraut56 said:
"A recent observation: With the car locked and inside my garage, if I touch any of the left door handles, the instrument cluster lights up, and goes out again after about 60 seconds. (I can't check this on the right door handles, the car is parked too close to the wall).

When this happens, the battery voltage drops from say 12.50 V about 0.3 V, and recovers after the cluster goes out again (no charger connected)."


Where and how are you measuring this voltage?

I have the harness of the Ctek intelligent charger wired permanently to the battery. The harness terminates with a plug (part of the complete charger package), which I have routed to the outside thru the right tail light lens opening. The charger connects to this plug (which has a sealing cover), so when it is not connected, I use it to check the battery voltage with my VOA-meter.

OK, that gets interesting.

Basically, it is physically impossible for the battery voltage to drop to 0.3 vdc and then recover instantly.

You have a faulty connection somewhere on your new harness, or you don't have the negative hooked to a good ground. If both leads are connected to the battery terminals, you have a faulty connection somewhere.

It is not recovering instantly, it takes a minute or so.
EDIT:

I believe my installation meets what you show in your procedure at: http://www.benzworld.org/forums/w220...ml#post5652508, although I am connected directly to the battery (the positive has a 15A in-line fuse, BTW). The charging function from the Ctek external charger works fine, and it has the ability to detect "poor" connections.

I understand that the voltage drops due to a load on the system when the instrument cluster (and other unknown systems come alive after I touch the door handles (BTW: also the right door handles).

What I am after is whether this is normal, or should the car modules be completely asleep. I have previously in another thread shown that battery load cycles with the trunk latch engaged about 2.3 A; cycles down to 1.2 A for 2 minutes, sometimes down to .8 A, but then immediately pops back to 2.3, but it never reaches the "required < 60 mA. I have NOT shown that with the trunk actually closed, as I would have to build a shunt between the battery ground terminal and the ground wire clamp.

thnx for yor input, and maybe you have some thoughts on my problem.

"What we've got here is failure to communicate." The Captain, in Cool Hand Luke

There are two items for discussion - the voltage drop, and the current draw.

Current Draw:
Checking the current draw on our cars at rest is not a simple exercise. There are quite a few modules that remain "awake" for some time after the key is removed, and having any operator activity will prolong this time. I have not done this test yet, so I do not know the specs on time before the minimal current draw is expected to be achieved. I do believe that you would need to install a current shunt in the ground cable, as you stated. I also would want that shunt to be made of wire heavy enough to ensure that the trunk-opening system could function with the shunt installed. I would use two 4' 14-gauge wires clipped or twisted together at the outer end and run out at the bottom of the deck lid. I would then connect the ammeter to the connected ends of the wires, and then separate the connected ends. This would keep continuous power flowing to the car's systems, so it could make a normal shut-down.

I would write down the current flow immediately, and then every fifteen minutes or so. I would expect the current flow to decrease within thirty minutes, but that is pure speculation on my part. Certainly, two Amps of current draw continuously would be a major problem. My car has the standard Mercedes battery, which is a 100 Amp/hour battery. I would expect a two-Amp draw to cause problems after 30-40 hours.

After the test is completed, I would reconnect the ends of the wires before disconnecting the Ammeter, and use the full current-carry ability (actually called "ampacity") to allow the trunk-open system to function.

Finding the culprit would be interesting. The usual method on other cars is to pull half of the fuses and repeat the test. If the current draw drops, you replace half of the fuses that you pulled, and repeat the test. Eventually, you will hopefully find the problem.

Voltage Drop
IF the battery functions - that is, if it will start the car, it is physically impossible for the voltage, measured at the battery, to drop to 0.3 volts. The battery is capable of putting out 200 Amps for several minutes without dropping the battery voltage below 10 VDC. If you put a 50-Amp drain on the battery, it should take two hours to drop the battery voltage to below one volt. If the battery is in very, very poor condition, it should still take over thirty minutes to totally kill the battery.

If the battery voltage should drop to less than one volt, it will not, physically can not, recover to a normal twelve volts without extensive recharging.

If your voltmeter is measuring voltage across the battery terminals, and is showing less than one volt, there is a faulty connection somewhere in the circuit.

When you touch the door handle, and the current flow increases to five or ten amps, the battery voltage should not drop more than tiny fractions of a volt.

"What we've got here is failure to communicate." The Captain, in Cool Hand Luke
 

Wallyp:

Yes, that was a good movie!

I think the failure to communicate here is: The voltage as measured across the battery terminal, connected with o-lugs to the battery clamp bolts, drops from say 12.5V BY 0.3 V (i.e. down to 12.2V), not down to .3V, and then recovers in about a minute.

I know about pulling fuses to eventually find the culprit user circuit, but I have avoided that so far because:
a) It's really crappy weather here in Montreal (winter), so I got the car in my garage
b) My garage is way too small for this car to do any meaningful work
c) Once I go thru the endless pulling of fuses, I will have to reset systems quite often, which also means running the engine etc, which right now I am trying to avoid (too cold with the garage door open).

BTW: The car starts just fine; during start the battery voltage as displayed on the intsrument cluster after pushing RESET three times drops from say 12.4 V NEVER below 10.6V, so I assume the battery is not at fault.

So I am putting certain jobs off for now, but I am working on one rather unusual possibility: The alarm siren is dead (integral battery most likely due to age), so the alarm system cannot come on when you turn off the car and close the doors, due to "no communication" (sounds familiar?), and somebody reported that that can prevent certain modules to go to sleep.

So my plan is to next replace the alarm siren, before I dig any deeper, because the alarm has to work as per the book.

Interesting, eh??

Please continue your thoughts on this!

thnx

Yes, one little word makes a huge difference. I'll try to read more carefully in the future.

aw; come on, this is all fun.

give me your thoughts when you feel up to it!

No hurty feelings here...

I have spent hours tracking down an irritating current drain on my Porsche 928 - a complex electrical system, but not even in the same league as the Mercedes. The problem there turned out to be a leaky power SCR in the amp for the cooling fans. Ordered new ones, opened the box and installed them, and problem solved.

My short experience with the S430 makes me think that many problems are computer-based. Sometimes, it is because one of the computers is doing what we told it to do, not what we wanted it to do. Sometimes, it is because we don't know how to tell the computer what we want it to do. Sometimes, it is a long-term computer response to a short-term problem, as when I got stupid and turned on the ignition with a door harness disconnected. The computer saw a disconnected airbag, and immediately killed the entire airbag system. I had to buy a Star System for that one.

Again based upon my limited experience, it seems as if you will either have to go thru the slow, frustrating search and eliminate process, or use DAS to help find the drain. I really don't know yet how helpful DAS would be...

Good luck! I will be happy to act as a semi-ignorant but cooperative sounding board.

Battery Drain and DAS
 

thnx Wallyp for your brainstorming.

Yes, I have DAS, but have used only once so far, see:
http://www.benzworld.org/forums/w220...ml#post5537561

Since I have no training on this system, I have no idea on where to start testing or scanning for battery drain or module shut-down time issues.

Maybe Eric will be able to shed some light on the "awake 4 door handles".

thnx again

Battery Drain problem - update from eric242340
 

Eric242340 has been very kind and responded to a PM of mine.
It is posted here so all forum users can benefit from his help.


Could you do me a favour and look at my post:
https://mbworld.org/forums/s-class-w...-go-sleep.html

I get a lot of good advice, but, my real question is:

a) the 4 door handles stay alive to the touch all the time; is that normal?

b) if not, then where or what module/circuit shouls I look at?

Post your answer anywhere.

thnx

Ulrich[/QUOTE]

If the key is far enough away from the car then touching the handles should have no effect whatsoever. Are you sure there is not a spare kg card inside the car somewhere?

If not then you most probably have a SAM problem, possibly the rear SAM (signal aquasition module) you will need to us star diagnostics to check this one out.[/QUOTE]

Thnx Eric!

I am aware of the keycard proximity, however, I have both cards far away.
If you mean also the key fobs, the fob from my other MB350 has been close by - I will keep both away to check!

I do have a Star system, but have used it only once with the quick test to successfully clear all faults and history. To get into checking the rear SAM I will need some learning/instructions. (maybe a new thread).

Since I am also not sure about the trunk locking (although it does), I would appreciate a schematic of the trunk locking/control system, or a hint where I could find that. So far I have successfully refilled the hydraulic actuation system, see http://www.benzworld.org/forums/w220...ml#post5640847, but i am not sure about the soft closing - it just slams closed and locks.

thanks a million![/QUOTE]

Rear SAM module - Eric242340
 

I checked earlier with the STAR/Xentry and had recorded it with my camera; it showed that the 4 door modules and the rear SAM were ok after the "quick Check", i.e. check marked. I later erased all faults and history.

Question is: What do I do next?




[IMG]file:///C:\DOCUME~1\ULRICH~1\LOCALS~1\Temp\msohtml1\01\cli p_image002.jpg[/IMG]


[IMG]file:///C:\DOCUME~1\ULRICH~1\LOCALS~1\Temp\msohtml1\01\cli p_image004.jpg[/IMG]

Next, is to enjoy your car and don't worry.

Ok, to stop this issue I went out and here is my feedback:
- My car does the same thing as yours which is normal, I believe.
- Make it accurate, all four door handles, after I touch the metal area, 1 second, IC light up.

Case closed and go to sleep my friend.

Howard

Howard's reply - door handles
 

Hehe Howard,
thnx for looking into this for me; no other replies.

Yes, I won't lose any sleep over this, but it fascinates me (and I am a bit of a perfectionist - my friends say).

Now, to really confuse things: After about 10 days of me checking door handles (all 4), and locking and unlocking and turning ignition on (but not starting the engine), all of a sudden the door handles are mute, i.e. they don't react to the touch anymore. Go figure!

So maybe on the same track: I know my alarm system does not come on; don't get the red light flashing on the dash switch, and no chirping when locking the car, and no reaction from the panic button on the key fob.
So far I believe it is the alarm siren with a dead battery, but I have to take the left inner fender off to get to it, and my garage is too small.
On some other thread I read that a dead siren integral battery can prevent the car from going to sleep, because the alarm system does not get communication from the siren.

Does your car chirp or react to the panic button?

BTW: The siren battery life is about 7 years.

thnx again!

Yes it does, just tried.

BTW, if you hate someone, just keep touching his handle, then his battery will die, :D

Have a great day!

Howard

did you have the keylessgo card with you when you got near the car?

PS also see what I am proposing on DAS/Xentry as a sticky - more and more people are getting into it.

No, no card.

For sticky DAS info, which may not be proper. I may be too concervative to advertise members are using unauthorized someware, just don't want the forums get into trouble.
Sorry, just my own opinion.

Howard

Howard,
thnx for the reply on the keylessgo cards; interesting that my doorhandles are mute now. I wil take the car out once the weather improves, and start all over again & monitor.

I agree with you; getting into the use of "somewhere" is outside this forum.
But I don't think use & procedures description of the system should be "off" for the forum, you can get a lot of that on youtube anyways.

It's a question for the monitors to decide if there's a conflict.

Once the weather improves, I'll belt this car west towards Toronto, maybe we'll touch base then.

BTW: What is the longest time you've left your car at rest in days?

Cheers!

Ulrich

At the beginning of this year I left her for over ten days many times. Never had battery problem, mine is 2003 though.

Just discovered a new battery drain - I walked behind my S430 while talking on my cellphone, and the car Bluetooth captured the phone. The car had sat overnight...