Red battery dash warning W211

[motocod]

Hi Folks,

The last few days I’ve been getting the red workshop battery warning on my dash. Some Googling suggests it could be the Aux battery. The car is a 2005 E270.

I understand that the main battery should be disconnected before the Aux. Can anyone confirm this? Also, where do I find the Aux battery?

Finally, can anyone recommend a good supplier that won’t cost the earth?

Thanks in advance!

 

[onefortheroad]

Possibly top right corner under the pollen filter . Main battery first then aux refit in reverse order.

Batteries can be found on ebay, euro car parts , tania , gsf, etc etc .

 

[ajlsl600]

Tania bosch,google.

 

[motocod]

Great, thanks guys.

 

[mioba]

get a v meter across the battery with the engine running to see what the alternator is pumping out - ruling out alty side

check battery after switch off and again after a couple of hours to see its holding - determine if battery side.

mb genuine batteries very good and last a very long time!

 

[motocod]

If I’m honest, I wouldn’t know what I’d need to look for with a multimeter, unfortunately. I’ve owned the car since 2014, and it’s a 2005, so I’m guessing it’s just in need of replacement. Seems like Tayna will do a replacement for around £40, and an MB one is about £60.

 

[EmilysDad]

If I’m honest, I wouldn’t know what I’d need to look for with a multimeter, unfortunately. ....

you should see around 12.7 volts across the battery after it's been left standing an hour or 2. You should see around 14 volts across it if the engine is running.

 

[Botus]

its normal,

replace the rear battery message will go away for a year then come back

 

[Botus]

I did the aux too, rear one still complained inside 3 months, cold temps and lack of use are the cause

the warning is for interior consumer toys, the front battery is for the brakes

in the spectacular way they wired it up at the factory with this message on, you may find for 20 mins after start up the interior blower motor will not run, nor do the windscreen washers work

 

[motocod]

The warning goes off after driving, so I’m guessing it’s charging ok, but I’ll check it before ordering a new one. Looks like a few options out there. Just checked and it’s the original MB one in the car, so that’s done well. I’ll get the meter on it when I’m home in a few days.

Thanks to everyone for your advice and help, really appreciated.

 

[motocod]

I wouldn’t be surprised if the rear battery will need doing at some point too, as I tend not to use the car that often. Although when I do it always gets a long run, so the other (not red) “convenience functions disabled” message always goes away after a few minutes.

 

[Botus]

as my father uses his less and less the message is there more and more....

front is one year old rear is now just less than 2 years old. Genuine AGM original fit Merc batteries, even if on a ctech charger for a week, the light will comes on inside 2.5 weeks these days

front battery issues is a more exciting message, (its purpose is to help the brakes work when the gas has run out on the accumulator - which does the effect of the servo - I believe)

at the back there are 2 rear battery states of unhappiness level 1 and 2 (you see in diagnostics, the message on the cluster is one only), both mean its low on charge and holding off features to allow the alternator to push a bit of energy in there first

 

[Botus]

if your budget is low, you can try and top them up with a small amount of distilled water, then give it a long charge....

oddly the AGM design slowly recovers over 6 to 9 months once the AGM absorbent glass matting is wet again, Most lead acid batteries die due to sulphation and the lead falling off the plates. When it shorts the plates it kills it dead. That can't happen in an AGM battery and the "tissue" of an AGM seems to hold both elements at bay for a long time. However the AGM material which looks like white tissue paper is no longer conductive once thoroughly dried out and it stops working.

the rear battery: under the sticker has 6 screw top lids but are a right nuisance to unscrew... they have two O rings on each bung and stick fast !!! You shouldn't but its the only way, get some lube there to help. Then put 70ml of water in each cell wait 24 hrs and look to see if the cell tissue puffed up OK. If its just damp and covering the plate all good otherwise add 20ml each time till each cell looks just damp. Do this and it'll go another 3 years at least

the front: is another story there is a bonded on plastic cover hiding any maintenance opportunity. Using a Stanley knife or a dremel it will allow you to cut off a rectangle then you'll find 6 rubber bung lids. it will be bone dry. As its a tiny battery that's never done anything in its life, try 30 ml each

both will recover to 90% of a new one...

My original 2006 one is as good as new (its replacement died just before the end of a 5 year warranty !!!), I topped it up a second time after 18 months,

my Bike posh AGM heavy duty military grade one gave up. Its even guaranteed to hold charge for 10 years disconnected and never touched …. then one day it was just dead. I tried to top it up and each cell took 140ml of water !!!! its only a 5 kg toy. 2 years on its as good as new.

 

[AMGeed]

This one is a good buy if you replace the aux battery.
https://www.tayna.co.uk/car-batteries/varta/mercedes-aux/

 

[mioba]

dealer original last donkies

 

[bigasotonuk]

Hi,
Aux battery OEM is FIAMM and is an AGM 12AH, there is a series of numbers on the top of the battery eg. 26.15 = 26 = week no. & 15 = 2015.
As it is only fitted for the SBC Brakes, Anything over four years old replace it (as recommended by MB If it is causing any issues or have a reason to believe its faulty).
Drop the earth terminal off of the boot battery first before replacing.
Aux battery fitted under the Pollen Filter.

 

[motocod]

This one is a good buy if you replace the aux battery.
https://www.tayna.co.uk/car-batteries/varta/mercedes-aux/

This is exactly what I’ve ordered. Will fit it later.

After disconnecting the rear battery will anything need re-setting? I’m assuming there will be back-up batteries in things like the dash and radio, so should be fine for the ten minutes or so it’s disconnected.

 

[Botus]

there are posts this week saying things go pop.... with old modules either getting fried and or losing vital vehicle data till they misbehave....

no car should do this, but old cars wear out and if a module is near end of life it may die, nothing I can see that can change this. Just connect things whilst the car systems are asleep and its unlocked. And don't phaff about, clean the terminals so shiny on the car and the battery before fitting them, get them the right way round and connect the earth last, bang it on firmly once, and don't get multiple sparks being a girl about it. And if the alarm goes off, get the terminals, tight before operating the central locking

window and sun roof anti trap may need reset.... manually hold closed, then hold up the switch and waited a few seconds after closing you MIGHT just hear a tick or thud as it learns what closed feels like, then let go job done. Do each window and the sunroof for TILT and slide.... that one just caught me out, didn't realise tilt close needed the same proceedure

 

[motocod]

Varta battery fitted. Nothing bad happened, and the only hassle was I had to re-set the clock, which meant understanding how to navigate the menus in the settings thing!

Also, the battery terminal screws weren’t long enough to engage on the threads, so I had to hold the little threaded nut thing up with an Allen key, which was fairly fiddly. If it hadn’t been for that it would have only taken ten minutes. Anyway, job done.

Ball joints and brakes next, although I might have the local garage do them, as it’s not exactly a good time of year to be working outside.