Originally posted by imtheguy Thus I wondered if it was a "smart" battery.
My answer is yes..... I have some DX batteries from HK, which look almost identical in every way and even work perfectly, and give identical performance to the originals. However i recently noticed an issue with my A-50mm f/1.2 & K-7.
This lens requires me to enter the Focal Input Length of 50mm every time i turn on the Camera. However when i swapped to my 3rd party battery, the Menu that appears when turning on the Camera asking to input focal length, no longer appeared. Not only that but manually entering the focal length in the menus, after it's turned on, also refuses to register a focal length.
I kept using the battery and at around 50% depletion, the focal length menu, returned to asking me for the focal length, as normal when turning the camera on. The original Pentax battery asks every time, but the 3rd party battery does not invoke the menu screen until it's almost empty.
From that i take it that these are smart batteries, and the voltage required to invoke that menu is set via a certain voltage calibrated to Pentax's battery.
I.e The 3rd party battery has too much current or voltage, and thus when the Camera tells the battery to output a certain voltage (to make the menu appear) the 3rd party battery isn't dipping it's voltage quite low enough, and thus doesn't activate the menu.
When the battery is less full however, when turning the camera on it's hitting the magic numbers that the original battery is hitting, and thus the menu appears again.
So i believe my 3rd party batteries are technically supplying a little more power. And indeed when looking at the sticker my 3rd party claims 7.4volts, and the Pentax one 7.2volts. (They both claim 1860Mah)
PS... I Have also seen the same issue you mention with the lockup, and numbers staying on the TopLCD even after turning the Camera off. So i do believe this is a battery, rather than K-5 bug or issue, it's just particular about batteries.