Sweet! I had forgotten all about this. I remember hearing about this a number of years ago, but it had slipped my mind, and I was about to order a bunch of AAAA batteries again for the several Streamlight Stylus lights I have. I checked my battery drawer and I have a bunch of 9V batteries on hand and I seldom use them for anything except for our smoke detector.
I quickly pulled apart an Energizer and a Ray-O-Vac 9V battery. The Energizer battery will work to harvest AAAA sized cells, but the ROV has the stacked Pez-sized cells of a completely different design. The Energizer harvested AAAA sized cells are approximately 1/16" shorter than true AAAA cells, and have the raised button on the negative end instead of the positive. A tiny piece of wadded up tin foil corrects the length difficiency, and I'm back in business with my Styli!
All four Energizer 9V batteries I have on hand have an expiration date of 2007, and they are down to 1.45V each, but they get the job done, and it is a lot better than having to throw the 9V batteries out and buy new AAAA cells.
