Batteries being like tyres are black and unobtrusive
 

Hi
This is my first post, other than to introduce myself. I have a query about which type of battery should be fitted and what make to my A8 3.0 Tdi quattro. It is a 2005 model and has a 110 amp wet battery fitted currently. See what I did there?

I have numerous niggly electrical faults which may or may not be antagonised by the fitting of an incorrectly specified battery. My simple question therefore is was the car originally supplied with an AGM battery and has anyone any experience having fitted one if not.

I have owned various Mercedes-Benz in the past and one model in particular was beset with issues simply because a previous owner had compromised on battery specification thinking they were saving money. A case of out of sight, out of mind, rather like trundling around in an A8 on tyres from Poundland and wondering why it isn’t a great experience.

I am hoping that someone will confirm what I suspect and advise a change to AGM. Then I can start to resolve the other things on my to list. I will be asking advice again therefore, if that is okay.

Thanks

It never had an AGM from the factory, but if you want to fit one, they work well. They are usually 92-95Ah though and the AGM coding for 95Ah is 3D0915105CE or 000915105CE - this would need programming in to the BEM (battery energy manager).
I had had a LION AGM from Eurocarparts and it has been fine for 6 years and survived a lot of total drains caused by gremlins.

One of the main root causes with the A8 electrical problems is undercharging caused by an overheating connection behind the insulation in the driver's footwell.
There is a thread here about it with photos.

Thank you for the information. I’ll search the thread out and I will also put a trickle charge on the battery. If I have the correct specification then I will give it every chance to recover as it has not run flat, apart from when it was in a garage a few weeks ago. I do understand that alternators do not always fully replenish a battery.