Ni-MH Gold Standard
December 5, 2014
Eneloops have an excellent reputation, and in my experience it's well deserved. Low Self Discharge chemistry means that you can charge them and then leave them in a flashlight, radio, remote control, etc. for years without significant self-drain occurring. Unlike higher voltage rechargeable chemistries, Ni-MH is safe, tolerant of overcharging and over-discharging, and can be stored at full charge without shortening overall battery service life.
And in high-drain applications (such as flashlights), Eneloops will actually perform better than alkaline batteries, giving you longer (and sometimes better regulated) run time. The best thing, though, is that these batteries won't leak like alkalines. I've replaced every pretty much every battery in the house with these (the only exception being my thermostat), and plan to never buy another AAA or AA alkaline battery again. :)
Oh, and they are an environmentally-friendly choice as well... if you invest in a decent charger, you can conceivably re-use these batteries for decades... during which time they will pay for themselves many times over.
Pros:All said above... a great replacement for alka-leak AAAs in almost every application you can think of. Especially in the case of low-capacity cells like AAA -- where the retail cost of a AAA battery is somehow the same as a AA battery -- rechargeable is the way to go.
Cons:The voltage on these batteries is expected to be slightly below that of fresh alkalines, so voltage-sensitive devices may not be a good fit. Example -- when I use AA-sized Eneloops in my thermostat, the "low battery" icon keeps flashing. The thermostat appears to work just fine at the lower voltage, but I opted not to risk it, and replaced them with L91 lithium cells.