Firmware bug in K-5 IIs
..or indeed on any of the many connections between the cells and the camera. Also, there could well be a semiconductor fuse in the output of the grip that is just tripping when the camera goes into peak load. That would be my favourite guess. A firmware problem would be well down my list.
If the EXIF contains the voltages then that would be a very good place to start.
|Glass by Hobbyfotograaf|
from High speed photography
|Northern water thrush by APenza|
from A Big Year - birds
|4th of July Outfit by Jack Sofield|
from - Old Age - (Black and White only + A Border)