haggisuk

I have been following this thread with interest, some interesting stuff indeed.

When I bought the S8 over a year ago it was suffering all the usual symptoms of a dying battery.

Historically as far as car batteries are concerned I have always put the biggest capacity battery in, and true to fashion I did the same again with the S8.

I never did any research if I'm honest so I went to the local battery centre and asked for the best that would fit in the car, his answer was an Silver AGM Varta which is advertised as a start stop battery with 950cca, when he tested it his tester showed that it had over 1000cca so I bought it.

Can't say I've been disappointed, I ran a test one day while monitoring the measuring blocks showing current draw and voltage levels while having seat heating, Stereo, etc on I was hoping that the battery manager would get to the point of turning consumers off but after 45 mins I got bored and gave up.

It's never once dropped of the 100% mark even after extended periods of fiddling with vcds etc.

As for lithium battery's they are too much of a liability for me that I would never consider having them in a car, just go on YouTube and look for lithium battery fires.

aTOMic

Don't forget that CCA =Cold Cranking Amps. Unless you were in a 32-degree(F) environment it should show far more than rated. What's the old chem-class rule of thumb; for every additional 10 degrees (F) a given reaction occurs 2X as fast? (I'm sure this varies greatly).
Also, I admit to being almost completely ignorant of lithium batteries but for their astounding lack of weight!

IIRC the venerable 2004 Phaeton had one in each side of the trunk, with one physically larger than the other; maybe the Touareg, too. As an EMT every ambulance I've done the pre-shift checkoff on had two, but they were both whatever the city could get cheapest. Now, I can understand leaving ambos running for the A/C for patient /crew comfort, especially in summer in the South. But police cars and fire equipment have them, too I think (however I've never personally checked under the hood of many of those). Gotta say, though, it drives me nuts they simply MUST leave them running for hours despite the fact they all have battery isolators which completely eliminate the possibility of a no-start condition. Just a little pet peeve.

MP4.2+6.0

SF Bay Area of course is where Euro car owners often drive around all year on summers only. But, when I head to Tahoe, you can see 10 below (F, not C) on more than a few nites. Where I am often records the 1st to 3rd nationwide overnight lows many winter nites. So, turning over 366 cubes at 12:1 does have me be sure batteries stay fresh and plenty of CCA's. Among the reasons I usually change them a little before last rites time. Second unexplained time it goes flat or cranks really slow is when I get the replacement.