Battery on preamps like Nagra PL-L etc repost

Has anyone tried connecting a 12v battery supply to the Nagra PL-L? The FAQ section of their website says this is possible:
"However, if you wish to use a battery on your PL-L, you can plug a 12 V battery onto the Lemo connector..."

Battery seems to be the in thing as in Dartzeel and ASR.

Any comparisons on sound quality vs mains?
Whoa! I am awfully curious about that, it might be worth an email to Nagra. I guess we'd be able to purchase a battery power supply like that in the PLP, but at what cost, and at what benefit?
For the curious, I have finally put together a cable set running my Nagra PL-L off a high-end car battery, and the improvement is probably equivalent to an upgrade to a totally new preamp. This is in comparison to running it from a variety of power products such as PS-Audio, Shunyata and Burmester...

Improvements include better handling of dynamics, especially on soaring female vocals and piano. Better timing between the interplay of musicians in jazz and rock. More natural harmonics from piano and violin. More expansive soundstage and space around performers. Improvement in background silence, especially on vinyl.

If you are considering an upgrade from your existing Nagra and can put up with the careful handling of battery cables and chargers, you MUST try batteries first. The Nagra must have been designed for this since its front panel switch has a input power voltage tester.
Kamil, so are you still using your Nagra PL L with batteries? I have a Nagra VPS and am thinking about getting a PLL soon maybe.

Any issues or regrets? Or is it really that good of a step up? Thanks