To add some of my own observations regarding electrical activity during sleep mode for a 2019 GLA 45:
-The blower motor sometimes does turn on after an hour or so after shut off. I've timed it, and it goes for just about 30 minutes. You can indeed feel a very gentle flow of air coming out of the vents during operation. At one point, using an amp clamp on the battery negative cable, I noticed a current of around 500 mA. This was after the car had been parked for a period of time, and the immediate module activity directly after parking was already long gone. When I pulled FUSE 202 in the engine bay fuse box ("Stationary Heater Control Unit"), the amperage dropped to the typical 50 mA quiscent draw that is always present when the car is sleeping. I looked at the WIS electrical schematics, and noticed that the blower motor is in some way connected with this fuse (it appears to also be related to a fuse in the passenger's footwell, and I have confirmed this by measuring voltage drop across the fuse while the blower was operating).
-When the car is in sleep mode, and even after it has been sitting over night, I have heard a hardly audible noise that has lasted for several hours that sounds like the flow of liquid through a pipe or tubes. It sounds exactly like a toilet tank refilling after a flush. To my ears, and using a sound detector app on my phone, it appears that the sound is coming from what appears to be a small black, cylindrical pump that is behind the driver's side of the front bumper. This may very well be the pump referenced in Post #25 above. I pinched most of the tubes coming out of it, but they simply felt as if they had air in them; I did not detect any change in sound, feel any vibration or evidence of flow, etc.
-On a few rare occasions, I have heard a very brief whistling noise from the engine bay after the car was in sleep mode for a while, exactly like the noise made when you let out a short burst of air from a balloon by pinching and stretching outward on the balloon's opening (didn't we all use to make that noise to annoy everyone when we were kids--or was I just a butthead? [Rhetorical question here]). It definitely sounded like a gas being released. I remember looking into it, and I concluded it likely had to do with the AC/evaporation system.
-Indeed, when there is an electrical draw such as the blower motor running, when the car is locked or unlocked, the windows are remotely lowered/raised, etc., the eletrical draw will cease.
-The SOS system goes off with some regularity as the car sleeps (maybe once per hour or even less). I am not sure if this requires that someone is seated in the driver's seat such that the seat weight sensors are activated. I have observed this SOS check many times while sitting in my car. I believe that I have witnessed it while not sitting in my car as well, since I have seen a few flashes of light coming from that location while walking past the car at times; but I am not certain.
Here are the results of a 2.5-day timelapse I made with a Go Pro camera set up to take pictures every 5 seconds while a voltmeter and amp clamp monitored the OEM MBZ main battery during sleep mode on my 2019 GLA 45. The X-axis shows time in seconds while the two Y-axes show amperage in A, and voltage in V. I opened and closed the door once every 12 hours in order to wake the system up and let it go back to sleep again, as well as to correct any drift that might occur with the voltmeter/amp clamp. The final spike is me starting the car (I had to truncate the A and V peaks in order to make the overall scaling appropriate).
Here are some conclusions from the graph:
-It's hard to tell due to the scaling, but quiscent amp draw for my GLA 45 is definitely just about 40-50mA (I have tested/confirmed this many times beyond the above data, including using a higher resolution amperage setting on the amp clamp than that used above). I had no peripheral devices that draw from the battery with the vehicle shut off.
-There are uknown voltage drops that occur every once in a while (I suspect that at least some of these are due to the aforementioned SOS testing, as some of the timelapse images show a light flash near the top of the windshield--perhaps all are due to SOS, but I would not know, as an image is only taken once every 5 seconds, and the flashes do not perist for quite that long).
-It can be seen that voltage and amperage are inversely related, as would be expected. If you look at the raw data, it's amazing how closely they are correlated. I used two completely separate devices to measure the voltage and current, and even tiny fluctuations in current consistently correlate with tiny flucutations in voltage--the sensitivity and consistancy of this amazes me and bolsters my faith in the fidelity of the measurements.
-The overall battery voltage recuperates after each drop, but it definitely slowly decreases over time. In this case, my battery went from ~12.55V to ~12.35V over the course of 2.5 days in ~50F weather (I should note that my battery's health during this testing was not the best; in fact, these tests were taken in order to gather information about the health of my battery during this time--I won't go into more details, but I believe the above data are applicable to the average OEM GLA battery (A001-982-8108, 12V 80AH 800 CCA, AGM) and shed light on some of the electrical activity going on while in sleep mode.
Anyway, the above are some observations I have made regarding electrical activity in the GLA 45 while in sleep mode.
