Thanks, so the VCDS is not voltage at battery terminals.
Here is more info about the lithium battery. Its put together by a company called Voltphreaks, and used in motorsport. Also a few people on the M5board have been using them for a few years.
Nominal voltage is 13.3V, fully charge it should be 14.4V, it is made up of 4 cells in series, 3.6V max each.
Weight is 4.9kg for the 59Ah version. Supposedly it will reduce the charging load on the alternator because it holds higher voltage than a Lead Acid battery (12.2V 50% discharged), so in theory it will release a miniscule amount of horsepower.
The other main advantage appart from weight is that it has a low-voltage cut off, preserving enough charge to start the car when you come back to it even if you left the headlights on, etc. Also it has a built in on-off button.
Apparently it should last 5-10 years, although to be honest my original Audi Lead Acid 95Ah battery in my previous S8 lasted 7 years before it no longer held a charge.
I managed to get the 59Ah model they just discontinued at a discount, "only" £880 shipped. I guess you have to be really serious about performance to spend this kind of money. Probably not worth it and not noticable, but now I started this weight loss madness I feel I have to see it through to the end
http://www.voltphreaks.com/technology.php
