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I had my S350 W221 2011 since September 2017; it got a new battery on day two (was still the factory one); all good; however, it was sitting under the carport over Xmas holidays, for 4 weeks without being used, and when I was starting it two days ago, it wouldn't crank the starter. Battery flat. Jump-started it, and drove 20km; all good for the next morning and subsequent starts.
Reading up on the forum posts, it can be a range of things:
a) dead battery (mine is new)
b) seat controller (maybe)
c) some other module not going to sleep (maybe)
d) key-less go (maybe)
e) door not closed and interior lights (nope)
f) electrical modifications (stock car)
Before I was going to put an Amp meter into the circuit and pull fuses, I was wondering: Will the car drain the battery less when it is locked, and not touched for four weeks; or (as I do) leaving the car unlocked, and opening the driver door once per week (to get something, or check something) -- which brings the dash light on, and possibly wakes up the car. On these occasions some air puffed in the front (not sure what it was doing)... maybe this triggered the car to somehow wake up (at least a bit) and drain the battery? Or should I avoid going past it w/o a key in the pocket?
My questions may sound silly, but I know the car reacts to opening doors, and the proximity of the car key... so it must be doing something.
Is it advisable to use battery tender? Is this really necessary?
I have a similar situation. I dont drive my E as I do the S, therefore, I found the battery wearing down. I know for most cars, and most certainly in the case of the E that my short commute didn't charge the battery. So in your case, the battery probably died completely of charge. To remedy my problem, I got a CTEK battery charger/tender and it works great. Get it direct from the manufacturer, they dont honor warranty if you get it through amazon. https://smartercharger.com/products/...-multi-us-4-3/ I make sure to disconnect the negative and positive terminal and connect the charger. No issues with the car firing right up.
Thinking the locks are either solenoids or actuators they will only draw power activate upon receiving the signal. Never done any tests to the amount of draw, but the cars' systems do use energy. I think the possibility of vampire/phantom energy from the ECU/PCM is more likely and higher than the locks.
BTW I think the puff of air is from the air suspension. No clue to why it does it, perhaps settling of the car.
I bought the car in Sept 2017 and drove it Mon-Fri 200km per day until mid Dec. Then it just sat there.
Battery new; no problems at any other time; always a solid start.
The main reason for my query was to test the theory, whether a "locked" car draws less, than an unlocked car, which may wake up when the key goes by.
The 'pfffft' is consistent and triggered when the car is parked, or a door opened (for a while?) --- not triggered at random; e.g. for no apperant reason.
I wonder, as I have never owned a car with air suspension to draw on experience.
I am thinking of variety of choices:
a) add a shunt into the negative side and measure the current 24/7 and see what happens; I reckon measuring the V over OBD port might be better.
b) stick a Volt meter into the OBD port and see how it drops over time (24/7) -- data logger
c) pull fuses while a Amp meter is in the battery loop; but here I do not know what the quiescent draw is, and when modules eventually go to sleep on the CAN bus.
d) or measure Voltage every day, same time, to see how the Voltage drops -- but, I mean I know it is dropping... just not how quickly.
I bought the car in Sept 2017 and drove it Mon-Fri 200km per day until mid Dec. Then it just sat there.
Battery new; no problems at any other time; always a solid start.
The main reason for my query was to test the theory, whether a "locked" car draws less, than an unlocked car, which may wake up when the key goes by.
The 'pfffft' is consistent and triggered when the car is parked, or a door opened (for a while?) --- not triggered at random; e.g. for no apperant reason.
I wonder, as I have never owned a car with air suspension to draw on experience.
I am thinking of variety of choices:
a) add a shunt into the negative side and measure the current 24/7 and see what happens; I reckon measuring the V over OBD port might be better.
b) stick a Volt meter into the OBD port and see how it drops over time (24/7) -- data logger
c) pull fuses while a Amp meter is in the battery loop; but here I do not know what the quiescent draw is, and when modules eventually go to sleep on the CAN bus.
d) or measure Voltage every day, same time, to see how the Voltage drops -- but, I mean I know it is dropping... just not how quickly.
... still thinking...
A-D might be effective on an older vehicle pre-W220 however you will likely chase your tail using those options on a W221. Start with a fully charged battery and load test it to verify it is 100%. The two most effective DIY options for checking the parasitic draw are going to be checking the voltage drop across the fuse poles (don't pull fuses) then checking the CAN blocks to determine which module is keeping the bus awake.
... checking the voltage drop across the fuse poles (don't pull fuses) then checking the CAN blocks to determine which module is keeping the bus awake.
OK, ...
1. Voltage drop over fuses... there shouldn't be any; fuses should not have any noticeable resistance, otherwise they 'burn' power.
2. check the CAN blocks; could you please elaborate on that? I would need to locate them? Or do they get their power form a fuse box I could tap into?
Is the quiescent current known on the W221? Or a range it should be in when 'asleep'?
Aha... further thinking and inspection revealed that this car has an Intelligent battery sensor right at the battery negative pole.
This can be read with a LIN slave or a STAR diagnosis tool; the latter seems to be the easiest, provdiding values for quiescent current, voltages, SOC, SOH, SOF, etc. nice!
... checking the parasitic draw are going to be checking the voltage drop across the fuse poles (don't pull fuses) then checking the CAN blocks to determine which module is keeping the bus awake. --Kyle
Hi Kyle; I need to apologise for dismissing your suggestion. I am glad to have the WIS where I can read up on things; which I have done for the last 7 hours!
And interestingly enough, your suggested method is described there. I wasn't aware, that they would actually use a micro-Volt-Meter (most common (least expensive) multi meters only resolve 100mV steps); and then calculate the current via Ohm's law based on the fuse resistance in the milli-Ohm range. I understand all that, but would not have thought that this is how it is done, in case a DAS is not available.
Why I later said: I am looking for a DAS... more so a clone... after I learned what I can read out; e.g. last power consumer, quiescent cut-off relay event, etc. WOW.
OK... looks like I am entertaining myself with my posts
Went for a drive today; to charge and observe the battery ... with vehicle data menu on.
As I figured out in recent days, the battery is only charged to 80% -- the reason why my battery is only 80% charged, even after a long drive, it is designed that way!
Basically, the alternator is off/disconnected most of the time. Only when there is a heavy electrical load, will the Alternator engage. When does it engage you may ask?
Apparently it has "brake charging". This means the alternator will engage when braking and when decelerating.
The logic? Have the alternator sap energy from the engine during these slow-down phases, rather than be a parasitic engine power-drain during other 'less-fuel-efficient' phases.
So, why the 80% limit? It needs a "free space" to put the brake charging into, without needlessly wasting "over-charging" the Battery.
As I found out, another example of BlueEFFICIENCY (which is the sub model descriptor) is the power steering. When driving straight ahead, who needs the power steering pump engaged? Hence, electronics manages the power steering operation.
Ignition on
Immediately after starting the engine
Though standing, this was pretty much the same while driving.
So, effectively, there is no point in trickle charging to full, as the car will drain it to 12.5V or there abouts... unless the car is sitting for more than a few weeks I guess.
Last edited by M-a-x-G; Jan 25, 2018 at 07:15 AM.
Reason: typos
I had my S350 W221 2011 since September 2017; it got a new battery on day two (was still the factory one); all good; however, it was sitting under the carport over Xmas holidays, for 4 weeks without being used, and when I was starting it two days ago, it wouldn't crank the starter. Battery flat. Jump-started it, and drove 20km; all good for the next morning and subsequent starts.
Reading up on the forum posts, it can be a range of things:
a) dead battery (mine is new)
b) seat controller (maybe)
c) some other module not going to sleep (maybe)
d) key-less go (maybe)
e) door not closed and interior lights (nope)
f) electrical modifications (stock car)
Before I was going to put an Amp meter into the circuit and pull fuses, I was wondering: Will the car drain the battery less when it is locked, and not touched for four weeks; or (as I do) leaving the car unlocked, and opening the driver door once per week (to get something, or check something) -- which brings the dash light on, and possibly wakes up the car. On these occasions some air puffed in the front (not sure what it was doing)... maybe this triggered the car to somehow wake up (at least a bit) and drain the battery? Or should I avoid going past it w/o a key in the pocket?
My questions may sound silly, but I know the car reacts to opening doors, and the proximity of the car key... so it must be doing something.
Lamp in glove box between front seats doesn't turn of. Put your mobile recording movie inside and close the lid. There's a small button in front that needs connection to shut the lamp of.
Is it advisable to use battery tender? Is this really necessary?
Lamp in glove box between front seats doesn't turn of. Put your mobile recording movie inside and close the lid. There's a small button in front that needs connection to shut the lamp of.
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Battery drain: is it better to lock the car?
