A209 CLK320 2004 - Bluetooth Adapter Question

[stevitee]

I have a Bluetooth Adapter MB Part No B6 788 000 fitted to the car. It works fine. My question is, does the adapter power down i.e not drain the battery when the car is 'asleep'?
I ask because I recently had sudden battery drain after the car had stood for about 10 days. I tracked it down to a failed alarm sounder (shorted, corroded battery/ies in the unit) and have disconnected it. Fingers crossed, that was the problem. However, I went to the car the other day and when having opened the door but not put the key in the ignition, my mobile rang. I answered but found that I was connected to the car's audio system via the Bluetooth adapter. Either the adapter 'wakes' up when a Bluetooth signal is nearby or the unit is on all the time, hunting for Bluetooth signals and thus draining the battery, albeit, I guess only at a low rate. If you can clarify this for me I will be grateful.

 

[stevitee]

I have a Bluetooth Adapter MB Part No B6 788 000 fitted to the car. It works fine. My question is, does the adapter power down i.e not drain the battery when the car is 'asleep'?
I ask because I recently had sudden battery drain after the car had stood for about 10 days. I tracked it down to a failed alarm sounder (shorted, corroded battery/ies in the unit) and have disconnected it. Fingers crossed, that was the problem. However, I went to the car the other day and when having opened the door but not put the key in the ignition, my mobile rang. I answered but found that I was connected to the car's audio system via the Bluetooth adapter. Either the adapter 'wakes' up when a Bluetooth signal is nearby or the unit is on all the time, hunting for Bluetooth signals and thus draining the battery, albeit, I guess only at a low rate. If you can clarify this for me I will be grateful.

Well, that didn't create a response so I've gone about investigations of my own. Shared here if of interest.

I hadn't previously tested, properly, for a battery drain, I simply went for the obvious (i.e. the duff alarm sounder and removed it). Today I used the multi meter to test for a drain - following advice found on here - with the car 'asleep', following a wait of 20 minutes. The meter settled at about 42 milliamps, which I guess is fine. I then reconnected the batt and re-installed the bluetooth adapter and left the car to go to sleep once more. I returned 20 or so minutes later to find the adapter with its blue light on still (saw through the window and had left the armrest open). I tested the battery again and got a reading of approx 43 milliamps. My conclusion is twofold, firstly that the removal of the alarm sounder has resolved the battery drain, for sure and secondly, the bluetooth adapter is awake always but doesn't causes and insignificant drain on the battery.

Incidentally, I found this on Google and thought it an excellent tutorial on how to test for as power drain:

https://www.google.com/search?q=tes...e&ie=UTF-8#kpvalbx=_8b6GX4-FN_3S1fAPk5y80AI12

 

[Alfie]

Yes it shuts down and powers off. Power returns when the car is unlocked.