I understand that shipping is difficult in many places and there is some skill involved in making up battery packs. I have made up several hundred AA packs and 50 lithium C packs so have had lots of practice. A tac welder is more than $1,000 so making the C lithium packs is even more difficult. I live a couple hours from ISC so when I make packs I do it using their welder, the best of all worlds. I might suggest getting a few guys together and ordering enough batteries for a year or two at a time, split the postal costs and the shelf life of AA alkaline is 3 years at least. Or finding one diver in your group (dont all meg divers travel in packs??) who has the skill to solder packs and do a bunch at a time whilst your mates buy the pizza and beer, but only let the tech drink beer after the work is done eh?
There are safeguards built into the Apecs that alert you when your batteries are getting low, backlight quits first, then the lo bat indicator comes on. Neither of these will work when you are using 9v batteries and you run the danger of a battery failing with zero warning, as in, during a dive. Using the correct voltage packs will allow the system to help you decide when its time to change batteries.
Anyway, you can do what you want, but I didnt want any lurkers to read your posts and decide that your idea was a great one without knowing the drawbacks.
Thats what I think...
y'all should have seen the 10-12 foot waves coming in over the Bar this afternoon, I was out surfing down the faces of waves in my 26 foot boat...yeee-hawww!