Hi all, I'm new to the forum (and internet forums in general!) so please excuse me if I make any errors regarding netiqutte. I have searched through the existing threads and can't seem to find anything that answers my questions, so.... I'm having a bit of confusion over replacing the battery in an E320CDi (W211 - 2003 Registered)(VIN/Chassis Number: WDB2110262A248609) which I recently inherited and I'd be very grateful if someone could help clear a few things up. The battery was replaced by the previous owner twice, the last time only six months ago, and is now dead again. The battery currently installed is a convential type 70Ah 760CCA. I called a few battery suppliers from the internet and found out that the battery should be an AGM type (I called Mercedes and they confirmed this) and a lot of people said that would be why the battery is draining. Is this correct? Also I'm getting conflicting advice on what size battery to put in. Mercedes say the orignal battery was a 70Ah 760CCA. Some battery suppliers are saying that this is what I need and others are saying that this is underpowered and that I need a 90ah 800CCA battery. To be on the safe side I don't mind spending a bit of extra money to and puting in a larger battery (there is plenty of space) but when I e-mailed Varta this is the response I got: - You can upgrade the battery to 95AH, 850 amps AGM battery which will be part number 595 901 085 (short code G14) however there are a couple of things that you need to make sure of before doing so. Firstly this battery will be longer than the 70AH, the 570 901 076 that I recommended before has a length of 278mm but the 595 901 085 will have a length of 353mm so you will have to make sure it will fit. All other dimentions and physical aspects of the battery remain the same. Secondly you will need to check when fitting the battery at your local garage that other components like the alternator will be able to take the battery. A common fault is that an alternator does not allow for the extra capacity and will not charge the battery back up properly causing the battery to fail. So now I'm left more confused that ever. Are there benefits to installing a higher power battery? Will it damage the starter/alternator or will the battery itself fail? Would the cars software need updating if I were to install a higher power battery. Also, is it best to go for a decent make like Varta or Exide and others just as good (I have a price for an Exide 90ah 900CCA that is much better than Varta's price for a 95ah 850CCA)? Thanks in advance for your help.