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Reading the comments from many others made me concerned that the Energizer lithium AA batteries sold here might be counterfeits. These are premium batteries and might be an attractive target for cheap substitutes by unscrupulous suppliers. Still, the subjective comments from some that the batteries failed too quickly could be easily erroneous or biased. How would I know? I purchased 20 of these batteries and decided to put one randomly selected specimen to the test. My sample had an etched code of “0716” and a printed origin of Singapore – does that mean it was manufactured in July 2016? I called this sample “0716-01”. I found a product datasheet for the Energizer Ultimate Lithium AA (L91) here -- http://data.energizer.com/PDFs/l91.pdf. One reads that this battery has a designed capacity of about 3300-3500 mAh (milli-Ampere hours) depending on the amount of current being drawn and the ambient temperature. For a current draw of 1000 milli-Amperes at room temperature, this battery is expected to run for about 3.3 hours (3300 mAh/1000 mA) before the voltage drops below 0.8 V. Looking through an assortment of power resistors in my electronics scrap bin, I found a 2.2 Ohm 5 W resistor that would do for a test. According to Ohm’s Law (V=I*R), this resistor will nominally draw about 700 mA dissipating about 1 W of power (P=I*V). At 700 mA, this battery should drive current through the resistor for almost 5 hours (3300 mAh/700 mA). The attached photo shows my experimental setup which used a Fluke multi-meter to measure voltage and a smartphone stopwatch app to measure time. I entered the recorded voltage into an Excel spreadsheet to compute the capacity and to produce the attached plots of voltage vs. time and capacity vs. time. Indeed, my sample Energizer Ultimate Lithium AA delivered a little more than 3100 mAh, near to the capacity stated by Energizer for this battery. Naturally I cannot vouch for the batteries delivered others, but I believe that I received legitimate Energizer batteries.