I’m a big fan of Sanyo’s Eneloop batteries. I bought a Costco pack which includes 8 AA, 2 AAA and a bunch of adapters for those pesky larger sizes. For the most part they work fantastically well and to this day most of them haven’t lost there charge, though sometimes I believe some to last longer than others. The versions I own are good for up to 1000 chargers. Yesterday, Sanyo announced a second iteration of their NiMH rechargeable batteries that are now good for up to 1,500 charges and will hold at least 70% of its charge for 3 years.
So what did we learn? Invest in Eneloops. You’ll totally get your money back and if you buy them from Costco you can return them once they start to fade.