[ssj555]

hi
i am having a problem everytime i start my car, i get the error message 'Battery Protection: Convenience functions temporarily unavailable.'

This happens most days even after a long drive, when i return i get the message. The car is stock with no extra electrical equipment,

This has been happening for over a month now and i have driven for long periods of time to ensure the battery is fully charged,

Any ideas. car is currently at dealers but they are saying this is normal and they are not going to diagnose for free.

Thanks
Surjit

 

[Noodles]

Is the main battery original to the car?

 

[olsb19]

hi
i am having a problem everytime i start my car, i get the error message 'Battery Protection: Convenience functions temporarily unavailable.'

This happens most days even after a long drive, when i return i get the message. The car is stock with no extra electrical equipment,

This has been happening for over a month now and i have driven for long periods of time to ensure the battery is fully charged,

Any ideas. car is currently at dealers but they are saying this is normal and they are not going to diagnose for free.

Thanks
Surjit

How old is the battery? According to the owner's manual when the battery is not fully charged the power is reserved for the car's main functions.

The alternator may not be working fine.

 

[sosh]

You most likely have a bad battery. Could be the main in the trunk or the small battery under the hood. One or possibly both should be checked and replaced if necessary. Can't believe you have driven for a month with no actions on your part. Do it before you are stranded where and when you do not want to be.

 

[fortlaudsummer]

Sounds like you need a new auxuiliary battery

 

[Noodles]

The convenience functions shutdown when the main battery drops to about 12.3 volts
with the engine off. I am not sure the aux battery is entering in this problem at all.

 

[realeric]

'Battery Protection: Convenience functions temporarily unavailable.' The car is stock with no extra electrical equipment,

I got the same message when I plugged a work lamp into the rear-center cigar jack. Checking the voltage would help you find the solution.

 

[Diesel Benz]

The convenience functions shutdown when the main battery drops to about 12.3 volts
with the engine off. I am not sure the aux battery is entering in this problem at all.

The AUX battery role is a bit mystery from the function descriptions. One would assume that the AUX battery voltage does not matter but owners using stationary heaters have reported the heater cutting off even if the main battery is fine and the AUX battery is isolated with the relay when the stationary heater is running.

Since the AUX battery tends to bring several different problems and it is cheap and easy to replace, I would in any case measure the AUX battery voltage and the main battery voltage (in the morning before starting the car).

Old threads cover a lot of info about the convenience functions switch off issue if it turns out to be something else than one of the batteries.

 

[ssj555]

both batteries are original, car is a 06 so around 4 years old.
I have checked the voltage using the car dashboard and get a reading of around 11.2 to 11.5 this is in the morning after car has been driven day before.

 

[vettdvr]

The AUX battery role is a bit mystery from the function descriptions. One would assume that the AUX battery voltage does not matter but owners using stationary heaters have reported the heater cutting off even if the main battery is fine and the AUX battery is isolated with the relay when the stationary heater is running.

Since the AUX battery tends to bring several different problems and it is cheap and easy to replace, I would in any case measure the AUX battery voltage and the main battery voltage (in the morning before starting the car).

Old threads cover a lot of info about the convenience functions switch off issue if it turns out to be something else than one of the batteries.

Just for discussion consider the aux bat. as a emergency back up to supply power to the sbc brake system. If the engine dies, main battery fails the aux battery will power the brakes.

If the aux dies you will get a warning but as long as the engine/alternator is running and main battery up your sbc brakes will work normal.

The aux battery is in it's own little world and isolated from running the car acc's and to protect the brake system.

If you have the Bat. Visit workshop it is probably the main battery. If you just have the (forget what it looks like) Bat warning it is probably just the aux. In any case voltage checks on the battery are the way to go. I confirmed my aux failing after it sat an hr the voltage dropped to 10 volts which is a dead cell in the battery. The life was about 5 years to push it. About 6 months after putting a new aux I got the Bat visit workshop. The full system check on the car was normal and the warning only came on once. I bought a new exact replacement AGM main battery and have had no alarms for the past 9 months.

Best of luck and hope you have a volt meter.

 

[Diesel Benz]

Just for discussion consider the aux bat. as a emergency back up to supply power to the sbc brake system. If the engine dies, main battery fails the aux battery will power the brakes.

If the aux dies you will get a warning but as long as the engine/alternator is running and main battery up your sbc brakes will work normal.

The aux battery is in it's own little world and isolated from running the car acc's and to protect the brake system.

I was not writing clearly, I know the role of the SBC battery but I mean the role of the SBC battery when convenience functions shut-off is declared, specifically when the engine is switched off and SBC brakes are not much of a problem.

Considering the AUX heater case, it should not matter for SBC brakes if the SBC battery was low and the AUX heater was still run from the main battery. At this point the SBC battery will not get discharged any further from other consumers. And as long as the main battery voltage is sufficient, SBC brakes would work fine once the engine is started and the isolator relay is closed. The front battery voltage would appear the same as the rear battery (minus some small load from the discharged small battery).

I assume MB just wants to reserve the full rear battery capacity for brakes when the front battery is bad, even when engine is switched off.

 

[sosh]

I was not writing clearly, I know the role of the SBC battery but I mean the role of the SBC battery when convenience functions shut-off is declared, specifically when the engine is switched off and SBC brakes are not much of a problem.

Considering the AUX heater case, it should not matter for SBC brakes if the SBC battery was low and the AUX heater was still run from the main battery. At this point the SBC battery will not get discharged any further from other consumers. And as long as the main battery voltage is sufficient, SBC brakes would work fine once the engine is started and the isolator relay is closed. The front battery voltage would appear the same as the rear battery (minus some small load from the discharged small battery).

I assume MB just wants to reserve the full rear battery capacity for brakes when the front battery is bad, even when engine is switched off.

I believe that the aux battery is for more than the SBC brakes as the ML series has an aux battery at least my 06 did do not know yet about my 10 ML550. The ML does not have and never did have SBC brakes. Its my take that this battery powers some of the electronics in the vehicle and even when shut down provides power to them as not to run down the main.

 

[fortlaudsummer]

both batteries are original, car is a 06 so around 4 years old.
I have checked the voltage using the car dashboard and get a reading of around 11.2 to 11.5 this is in the morning after car has been driven day before.

You may just want to avoid time / save guess and replace both of them for ~$200 and it is a DIY. They are nearing the end of their servicable lives so if it's one you'd have to replace the other sometime not too far "down the road".

 

[Diesel Benz]

I believe that the aux battery is for more than the SBC brakes as the ML series has an aux battery at least my 06 did do not know yet about my 10 ML550. The ML does not have and never did have SBC brakes. Its my take that this battery powers some of the electronics in the vehicle and even when shut down provides power to them as not to run down the main.

Now we are talking about totally different cars. My W221 has two batteries and does not have SBC brakes. But the front battery on the 221 is for totally different use than the front battery in the 211. I admit I have not looked at the ML but I assume it is more like the 221.

Even the 230 is different from the 211 although it has SBC brakes!

 

[Diesel Benz]

You may just want to avoid time / save guess and replace both of them for ~$200 and it is a DIY. They are nearing the end of their servicable lives so if it's one you'd have to replace the other sometime not too far "down the road".

I agree with this view, if the AUX battery is a bit old and the car has some battery related issues, it is worth changing the AUX battery "just in case".

 

[Noodles]

both batteries are original, car is a 06 so around 4 years old.
I have checked the voltage using the car dashboard and get a reading of around 11.2 to 11.5 this is in the morning after car has been driven day before.

That is low. My car can sit at below 0º temps for 3-4 days and shows 12.9 volts
with the SDS or a voltmeter. I would change the main battery first.