D3 Battery Recommendation

[Charlie]

My D3 needs a new battery - sitting at 14.5v while idling, but drops well below 12v when not running making it requiring a jump start most days, embarrassing! So in my mind, the battery is on the way out.

Mine seems to have a 'Normal' battery - have any of you guys upgraded to one of these AGM batteries? Worth the upgrade?

Does anyone have a recommendation for a well priced battery retailer?

The car is a 2006 Build A8 4.2 TDI Quattro Sport.

[sarg]

Bosch S5

[Goran]

When you get your new battery, don't let it sit below 12.3V~12.4V (no load voltage) for weeks. It will sulphate and reduce the effective capacity of the battery. Lead acid batteries don't like to be at below 50% state of charge.
My only 3 year old 110Ah Varta battery is struggling because the previous owner must have done just that, so it will charge 12.7V, but drops in minutes to 12.4, and after 4-5 days of no use goes down to 12.2. And I only have a parasitic drain of 0.2A ~0.3A

http://batteryuniversity.com/learn/a..._to_prevent_it
http://batteryuniversity.com/learn/a...tate_of_charge
http://www.batterystuff.com/kb/artic...ry-basics.html

Is a D3 solar roof wired to trickle charge the battery? if not that would be a excellent mod.

[Charlie]

I was looking at the Bosch S5 - some sites say type 019 others type 020 - I'm pretty sure the larger 020 will fit the D3 so I think I'll go with that.

Eurocarparts are doing it for under £115 (via eBay but collect in store) which is not too bad.

[sarg]

Try the discount code UKPASSAT25, it used to work...