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Battery protection convenience functions temporarily unavailable meaning solution


You may have been wondering why the “Battery protection: Convenience functions temporary unavailable” warning came up. Your car still runs and drives normal.

This warning will come up if you:
  • Leave the car sitting for several days, without starting it.
  • Let your radio or lights on with the engine off.
  • Have a battery that is reaching the end of its useful life.
  • An electronic system such as seats, sound system or others are draining your battery.
    mercedes battery protection conven funct unavailable

What does this message mean and why am I seeing it?

 The reason why you are seeing this message is because the battery voltage has dropped below a preset threshold. Several Mercedes-Benz models have two batteries installed on them such as the E Class W211. They have the main battery G1 in the trunk, which is a 12 Volt  60 to 95 Ah Battery Group 49.
They also have an additional battery G1/7, also called auxiliary battery (12 volt 12Ah)located  in the engine comparment below the cabin air intake. The auxiliary battery supplies energy to power the accessories but even more importantly it provides energy if the main battery voltage is low.
The voltage for these two batteries is monitored by the Battery Control Module N82 which is located in the trunk.  The battery control module will monitor the battery and manage the energy that is available on the two batteries. When the energy is used quickly it will disable “convenience functions” by switching off several electronic functions (consumers) in your car.   The N82 functions in two
Stage 1: Voltage drops below 11.0 volt
Stage 2: Voltage drops 10.5 volt
Function of N82 Battery Control Module BCM
  • Monitor voltage of main battery G1 and auxilary G1/7 battery.
  • Monitor alternator voltage at terminal 61.
  • Control auxilary battery relay.
  • Control on/off accessories privatization
  • Control the charging of auxiliary battery
  • Sets fault codes via CAN Communication and DTCs
  • Sends signal to display the instrument cluster fault message.
The reason the car does this is so that:
  • If there is an electronic consumer / accessories (for ex: heated seats) draining the car battery to rapidly, to stop the battery drain.
  • To save the batteries for critical situations such as staring the car and keeping the engine running properly.

What should I do to solve this problem?

If you left the lights on or the radio on and then you saw this message then just leaving the car to charge is all you need to do.  The first thing you should do is start the car and drive it or let it idle for at least 15 min. The BCM will allow the auxiliary battery to get a charge once the system voltage is over 13.5 Volt. It allows this one time every run cycle. Once the auxilary battery gets charged, the error message on your display should not come up on your next driving cycle. If you see the message come up more and more frequently check to see if your batteries need to be replaced.

If you have been seeing this message several times recently it is time for you to plan on replacing the batteries. Car batteries have an average life of 5 years so if your battery is old plan on replacing it.

You can get both the auxiliary battery and the main battery from Amazon and for much cheaper than the dealer. You can read reviews too to make sure to get a good battery. Replacing either one of these batteries is easy. Below are the two batteries that you will need:

If you replace the batteries and you still are having problems then you may want to check the GENUINE MERCEDES Auxiliary Battery Relay (High Current Relay) 0025424719

If you leave your car sitting for extended periods of time or would like to properly charge a dead / discharged battery you can use a trickle charger like the one below to maintain or charge a car battery properly.






  1. Abubakar Jibril Ibrahim Ramalan

    My air flow meter is giving me nightmares, I drive a Mercedes Benz(211) E500 2005 model and just of recent I started having air flow meter issues, when i am on transit and break for a bump or slowing down, the car goes off, an analysing machine was used and found the issue to be the air flow meter and some days ago, the radio and navigator refused to come on, when I press power it comes on then go off, I also changed the air flow meter like 8 times but, still having same problems, what do I do please?

  2. hi there, i recently purchased a second hand Merc e220 w211 (2005) and this message appears every saint day. i changed the auxiliary battery … but nothing. so i bought a delphi car diagnose system that helped me to identify the problem : BATTERY ENERGY CONTROL MODULE – BSG211 —> DTC : 9051 CONSUMER SHUTOFF STAGE 1(PERMANENT) and second DTC: 9050 CONSUMER SHUTOFF, STAGE 2(INTERMITENT). After erasing them, they still appear . But the problem that i have now is this one : i physically inspected the module at the back of the trunk but the part number is not the same as the one that is stated by Delphi. So, on the back, in the trunk i have A211 540 42 45 (that has a hand made hole in the casing and a white wire attached to mother board) but Delphi is reading from the ECU the following PART NUMBER : A211 442 01 55 .please help me

    • I would suggest that you call your dealer and ask them what the part number should be for that module. Also what battery did you use? Was it aftermarket?

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