Pentax dSLRs using AA batteries are well known/notorious for being battery fussy/sensitive. This extends all the way back to the *istD series through the K100D and now the K200D - it shouldn't surprise anyone that there are very strong family traits in these dSLRs
The cutoff threshold voltage is set at 1.19V per cell (total = 4.76V) below that and the camera shuts down.
This cutoff threshold is pretty high since the nominal voltage of rechargeable NiMH AA batteries is supposed to be 1.2V.
(Ref: Post #
49 (link) in thread -
K100D - "Low-Battery" Problem gives details of the meter voltage levels)
As many report often the camera shuts down after only a few disappointing number of shots, even when there is a large amount of remaining capacity - enough to power and run other equipment.
This is because the operating voltage under-load of the batteries have dropped below Pentax's threshold cutoff voltage (1.19V/cell)
This battery problem is so prevalent that there are always concurrent threads here on the subject -
eg:
K200D Batteries k100d battery recommendation
If one reads these threads a fairly common recommendation is to use AA eneloops in the Pentax dSLRs
I posted the below in the thread
k100d battery recommendation Post #
62 but I'll paste it here for your convenience -
....even among Low Self-Discharge (LSD) batteries the eneloop maintains its operating voltage under load better than other LSD batteries -
I have a long (and somewhat messy) thread over at CPF batteries section comparing the otherwise really excellent Kodak Pre-Charged (LSD) with eneloops actually in the Pentax K100D -
eneloop vs. Kodak Pre-Charged Voltage Maintenance - summary in post #
57
Here's an animated GIF showing the discharge curves at various current rates for 3 LSD batteries (note these were produced by SilverFox in his threads -
NiMh Battery Shoot Out and
Eneloop Self Discharge study - CandlePowerForums )
I've drawn a horizontal red line at approx 1.19V the cutoff threshold voltage for the Pentax K100D
(Ref: Post #
49 (link) in thread -
K100D - "Low-Battery" Problem gives details of the meter voltage levels)
One can see that there are more curves above the red line for the eneloop than the other two LSD batteries -
although this may seem minor, I think this is very significant for the battery fussy/voltage sensitive K100D and *ist D family of Pentax dSLR.
So although I do own Kodak Pre-Charged LSD (which are otherwise excellent) - I suspect these are
re-badged GP ReCyko? - I use eneloops and confirmed re-badged eneloops in my K100D over any other batteries.
To get over 1,100 shots out of a set of eneloops and also a set of DuraLoops (Duracell Pre-Charged - confirmed re-badged enloops for the made in Japan white top versions), both having been charged 3-4 months before use - is simply incredible to me.