So I bought an octet of Sanyo Eneloop NiMH cells from the usual Amazon source and ran a few charge / discharge tests, with the hope of powering my Sony DSC-H5 for more than a few dozen minutes at a time. It’s Marching Band season!
The cells bear a laser-etched 09-10-IF date code that I assume means October 2009, because they arrived in early September 2010. Rumor has it that Eneloop cells come off the manufacturing line factory-charged to 75% of their nominal 2.0 Ah; all eight arrived with the same charge: 1.43 Ah. Given the vagaries of measuring battery capacity, that’s 95% of what they started with, nearly a year ago.
The eight 500 mA constant current discharge curves are essentially identical:
The first charge after that test was individual cells in a 400 mA charger, the second as a complete 8-cell pack with a 900 mA charger. Those two discharge curves for the pack, again at 500 mA, also overlay nicely:
The pack voltage remains above 9.6 V for about 1.5 Ah, far better than the tired assortment of cells in my collection (albeit those were measured at 1 A, not 500 mA).
These should get me through an entire day of Marching Band travel, setup, practice, and competition!