W211 battery convenience functions while idling

[motocod]

Hi folks,

Bit of an odd one; I’m getting the “battery convenience functions” warning while I’m sat idling in traffic. It’s happened twice now, and clears within a few minutes once back up to normal driving speeds.

Two questions:

1. Is this relating to the little aux battery under the bonnet, or the big one in the boot? I replaced the little aux one only a couple of months ago.

2. Could this indicate a charging problem?

Thanks in advance for any advice!

Nik

 

[Blobcat]

Could be charging, could also be the main battery is low. Should be ~12.4 volts at rest with engine off. Should be ~14v when charging

 

[00slk]

As above, how old is the boot battery?

 

[motocod]

Boot battery might very well be the original! Car is an ‘05, and I’ve owned it seven years, and never replaced it. Starts and turns over fine.

I sometimes get the message on the dash if I haven’t used the car for w few weeks in the winter, and it’s been sat in the cold.

Wouldn’t be hugely surprised if the boot battery is a bit tired. Just seems strange that both times I’ve had this recently has been idling in traffic, having already driven a decent distance.

 

[Blobcat]

Boot battery might very well be the original! Car is an ‘05, and I’ve owned it seven years, and never replaced it. Starts and turns over fine.

I sometimes get the message on the dash if I haven’t used the car for w few weeks in the winter, and it’s been sat in the cold.

Wouldn’t be hugely surprised if the boot battery is a bit tired. Just seems strange that both times I’ve had this recently has been idling in traffic, having already driven a decent distance.

Mercedes can be very sensitive to low batteries.
The battery age should be stamped on one of the posts in a week and year format

 

[motocod]

I’ll check that tomorrow, thank you.

 

[grahamcol]

If it's an 05 on its original battery that is amazing. I recently changed the original battery in my 07 CLK and thought that was pretty exceptional.
It's true that Mercs do strange things when battery voltage is low and I've noticed it a few times. I guess an ageing battery will be prone to low voltage, even during active use with the engine running.

 

[mioba]

I am a huge fan of MB batteries, My w220 is on its 2nd battery and my w251 original.
My cars sleep in an undercover open garage so maybe not exposed truly to the elements.

 

[Adamki83]

Hi folks,

Bit of an odd one; I’m getting the “battery convenience functions” warning while I’m sat idling in traffic. It’s happened twice now, and clears within a few minutes once back up to normal driving speeds.

Two questions:

1. Is this relating to the little aux battery under the bonnet, or the big one in the boot? I replaced the little aux one only a couple of months ago.

2. Could this indicate a charging problem?

Thanks in advance for any advice!

Nik

Hey, not sure if any use I have an 05 270cdi and I get this message occasionally when it’s cold it was my accessory battery (the one under the pollen filter) it’s still an original battery I still haven’t replaced it message tends to go away when it’s warmer.

 

[motocod]

Thanks for your reply. I actually replaced the little aux battery a few months ago, so hoping it’s not that!