Another reply, mainly echoing kirk.
I bought two of those type of CCTV batteries, both were useless. Neither was the same storage amount, but both looked essentially the same with the blue shrink wrap.
First one I got from ebay/China, listed as 12v output, 6800mah. It worked fine for some initial testing, but first time I charged it, it blew up like a balloon. Not good for li-ion batteries -- scrap that (ok, recycle that). Next one came from DinoDirect (or something like that), also from China, also listed as 12v, 6800mah. It worked fine, ran the 680, used it only a couple of times, but it ran the 680 for far less than I was expecting. Then it died, wouldn't charge, no output voltage, useless.
I finally got around to dissecting it and it contained 3x 3.7v li-ion packs, so without upconverting the voltage, that would be 11.1V out, not 12v out. I never tested while it was working to see if it was 11.1V out or 12v out, so it may have stepped up the voltage to 12v. Thing is though -- the 3.7v li-ion packs inside were 4200mah packs. Yep, no wonder it didn't last as long. The 6800mah listing was just completely made up, it was a 4200mah pack at best.
Bottom line, stay away from this junk, the typical 9v DVD battery works great with the 680.
On the card speed, I first ran a (supposedly) Class 6 Adata 16gb card I had been using with the R44. It worked for 4ch at 24/48, but choked and ruined recordings with 6ch at 24/48. I have a Mac, so I don't know how to do actual speed testing on the card (which is now lost) and I thus don't know how fast it really was.
I replaced it with a 32GB Class 4 card from Kingston. It has been rock solid running up to 8ch at 24/48. I've never run above 48k, but I think theoretically 8ch at 96k sampling should be less than 2.5 MB/s write speed, so a true Class 4 card at 4 MB/s should be able to cover 8ch of 24/96 recording. From my experience, get a quality card from a quality mfg (Sandisk, Lexar, Kingston, maybe others, but that's who I trust) and just get a Class 4 or Class 6 card. No reason for Class 10, unless the mfg is mis-reporting their speeds.