Axillary Battery Malfunction

[MKopec88]

My Mercedes c class just had that wording pop up with red beeping flashes which turned to a white colour with no beeps.

Any idea if it's safe to drive with this or does it need to be looked at asap

 

[GeeJayW]

My Mercedes c class just had that wording pop up with red beeping flashes which turned to a white colour with no beeps.

Any idea if it's safe to drive with this or does it need to be looked at asap

It's a common issue. The auxiliary battery probably needs to be replaced. Had the same problem (replaced under warranty as car was less than 3-yrs old at the time). You can continue to drive the car, though stop/start function won't work and it'll nag you about the problem.

 

[MKopec88]

It's a common issue. The auxiliary battery probably needs to be replaced. Had the same problem (replaced under warranty as car was less than 3-yrs old at the time). You can continue to drive the car, though stop/start function won't work and it'll nag you about the problem.

Oh shame, mines a 2015 model so out of warranty. Will bring it to the dealership on Monday and see if it falls under the warranty I have with them or not since it was bought 2 weeks ago. If not then guess I'll be spending some money to fix it up

Thanks

 

[GeeJayW]

Oh shame, mines a 2015 model so out of warranty. Will bring it to the dealership on Monday and see if it falls under the warranty I have with them or not since it was bought 2 weeks ago. If not then guess I'll be spending some money to fix it up

Thanks

If you bought it two weeks ago, I think they should cover it under the approved used car warranty. It's not a wear and tear item. I've included some pictures above. There are several versions for the battery (which isn't really a battery), not sure the one I've shown is current, but it does show what it looks like. The offending item is located in the passenger footwell. A mate of mine changed his himself (car was out of warranty), but he is very handy around cars.

 

[MKopec88]

If you bought it two weeks ago, I think they should cover it under the approved used car warranty. It's not a wear and tear item. I've included some pictures above. There are several versions for the battery (which isn't really a battery), not sure the one I've shown is current, but it does show what it looks like. The offending item is located in the passenger footwell. A mate of mine changed his himself (car was out of warranty), but he is very handy around cars.

Muchly appreciated bringing it in tomorrow so hopefully it can be sorted.

 

[MKopec88]

Is this true about the auxiliary battery?

"Quick question about the key, are you using in keyless mode? as the key will need to go in dash from time to time to charge up thats all"

Dealership messaged me back with this. I trust you merc experts here before I go in tomorrow lol

 

[GeeJayW]

Is this true about the auxiliary battery?

"Quick question about the key, are you using in keyless mode? as the key will need to go in dash from time to time to charge up thats all"

Dealership messaged me back with this. I trust you merc experts here before I go in tomorrow lol

The keys have a button battery accessible through the side. Have replaced them in ours a couple if times in three years.

Never heard of needing to put the key in the dash for charging it, so not buying that one.

 

[MKopec88]

The keys have a button battery accessible through the side. Have replaced them in ours a couple if times in three years.

Never heard of needing to put the key in the dash for charging it, so not buying that one.

Hmmmm so apparently the car charges the main battery first and then auxiliary battery once the main is at max capacity. I found this in another forum. Heavy stop start use uses up the auxiliary battery and its what I use 99 percent of the time instead of the actual key fob. Will try using the key fob for a few days and see if it fixes the issue. Will take it in tomorrow regardless.

 

[GeeJayW]

You can turn off the stop-start function even when you have used the push button to start the car. Just press the button on the left of the central console. So no need to use the key to charge the auxiliary battery. I usually switch it off and have almost never used the car with the key in the dashboard.

The auxiliary battery supports the auxiliary devices such as the radio, heater blower and so on when the engine is stopped. It doesn't do the stop-start function as such. It certainly doesn't power the starter motor (as far as I know). It's not even a battery, it's a few large capacitors and a circuit board.

 

[MKopec88]

Right so it's defo a capacitor for the w205 merc not a battery. Would I be covered under warranty by looking at it?

Or will it still be considered as a battery and therefore not covered under warranty? Trying to get some heads up info before I head out.

Last thing I wanna do is spend money to remove a stupid malfunction sign that won't go away from the dash.

 

[andy27168]

Hi
I had MB approved used warranty on my 207 it expired 2nd June, complained about poor cold starting when it went in for a service approx. 15th June aux. battery was replaced under warranty no questions or arguments on whether it was covered or not, and despite my doubts on whether it would cure the issue I have not had any issues since.
Just mention the warning you have seen in the dash and get them to look at it as part of the service. Do not mention anything else until it has been diagnosed and they are trying to bill you for it but I bet if it requires replacement they will just do it without any question.

 

[MKopec88]

Faulty capacitor was indeed the issue. Replaced right away with no questions asked. Feeling pleased as punch

 

[Funkyboy]

If you do need to buy one get it from the tayna website. Give them a call and they will tell you which one you need. Mine was about £39 delivered. Five mins to change

 

[MKopec88]

If you do need to buy one get it from the tayna website. Give them a call and they will tell you which one you need. Mine was about £39 delivered. Five mins to change

Perfect!! Just bookmarked the site so thanks.