Originally posted by GSWayne I tested 3 brands of D-LI109 batteries for a K-30. The Pentax and the Synergy brand batteries were purchased in April 2013 and have been used regularly since then. The Wasabi brand batteries were purchased in January 2014 and have very little use before the test. The testing was done with a Optim Engineering CBA III computerized battery analyzer. They were tested with a constant 1A load. It discharges them to 5.6V and then removes the load. The cutoff point is not critical because once it discharged to 6V it drops quickly after that point. This is obviously not very similar to the camera load, but it should be a good indication of the relative capacities of the different batteries. All units were charged and discharged twice. The results were very similar in both runs of each battery.
Pentax had a claimed capacity of 1.05 AH and a measured capacity of 1.0 AH capacity (cost about $48)
Synergy had claimed capacity of 1.2 AH and a measured capacity of 0.6 AH capacity (cost about $14)
Wasabi had a claimed capacity of 1.4 AH and a measured capacity of 0.8 AH capacity (cost about $27 for 2 and included a charger that works from both 12V and 110 or 240V)
So the moral of the story is that the Pentax batteries are somewhat better than the aftermarket batteries, but cost much more per AH.
So pentax is $48 per AH
Synergy is $23.33 per AH
Wasabi is $17.50 per AH (checked price on amazon for single battery.)
Wasabi seems to be the best value. You just have to carry more of them.
Assuming the Pentax gets 400 shots per charge, (410 spec'd, but we all know battery specs are wishful thinking) to get 1000 photographs you need
2.5 Pentax batteries. (400 per battery)
4.1 of the Synergy batteries (240 per battery)
3.1 Wasabi batteries. (320 pics per battery)
So, to me this just means you use your Pentax battery, and keep a pair of Wasabi as your 2nd and 3rd if you shoot that much.
In my case, the most I shoot is my daughter's volleyball. The most I shot per day was 330. So, I could get by with just the Pentax battery. However, I will always carry a back up.