Recently I went through my Eneloop batteries, cycling those that I keep in devices. I decided to purchase another pack of AA and AAA batteries, not because I needed to replace any but because I have more devices to power. After ordering the new batch, I realized this was the first time I had purchased AA batteries in seven years. (I had purchased AAAs more recently – three years ago – again not to replace any, but because I needed more.) My seven year old batteries are still in service and hold on average 85% of their factory charge. I don’t intentionally cycle through the full set of batteries, so some sit in storage holding their charge for years.
It doesn’t get much better than that.
I started using Eneloop rechargeable batteries in 2011. The following year I purchased a programmable charger, allowing me to track the health of my batteries in git. When not in service I store the batteries in a Pelican 1060.