Comment by nickcw
Eneloops are fantastic. I've been using them for 10 years.
They have very low self discharge so you can keep them on the shelf for a year and they will still have 70% charge which is very different to most rechargeable batteries.
They don't leak unlike alkaline batteries and you can run them to 0% charge without damaging them unlike Lion batteries.
The terminal voltage is only 1.2v so there is the occasional thing they don't work well in.
That said my collection of eneloops get much less use than they used to as everything comes with built in lithium batteries and a usb charger nowadays. That is very convenient until the moment the lithium battery dies...
Changing the lithium battery in things sucks. Firstly it's really difficult to get a good one and not a crappy knock off. Secondly modern stuff isn't meant to be repaired. Every time I pick up my kindle I shed a small tear when I see the screen damage I caused changing the battery.
So, I buy stuff with AA or AAA batteries if possible and if I want it to last for more than 3 years.
The whole "everything I own just has a built in Li-ion battery" thing came to mind when I ordered my first set of Eneloops ahead of last week's snowstorm in North America - most things I own have their own batteries with a charger (right down to this decorative squishy whale lamp), and I can count on two hands the things that use AAAs and one hand the things that use AAs. It's wild.