Ran the K2>Tascam DR680 for four days at Lockn'...input was from Aerco MP-2 two channels line in (no phantom power or mic preamp ran on 680). At some point on Sunday afternoon the meter went down to one light. There was a one hour break before Phish...so as not to tempt fate I swapped it out for my old BG 10-14-115 but suspect I would have been fine.
Observations...I managed to kill a fresh set of AA's in the DR680 sometime between checking/packing Wednesday and setup on Thursday.
It prevented the DR680 from starting up with the K2 hooked up...a couple of minutes of panic until I realized the issued & dumped the AA's...not optimal with this unit but at least I was up and running. That night when I shutdown I swear the unit shut down as soon as I stopped recording. DR680 meters are back lit when on external power and I had not hit the power switch and the meters went dark...
$10 of AA's at the festival general store and this didn't happen any more...also I have not been able to reproduce this behavior at the house.
After DR680 shutdown the meters on the K2 go dark immediately, if you hit the power button again on the DR680 it powers right up to external power and the K2 Meters light up also. But, after shutdown I think the K2 stays on more like 30 Seconds instead of 30 minutes. More than 30 Seconds you must hit the power button on and restart the K2.
Hitting the power button while there is a draw on the K2 does nothing...that is comforting.
The K2 Really does require 4hrs or more to charge...
Overall I'm very happy with how it provided Festival Power. It is a Heavy Beast though...Would love to find a compact way to step down 20v 3amp to multiple 2 -12v and 7.2v (Grace V2) outputs. That way I could get a F8 and run the Aerco and Grace Pre's off one large battery.