I’ve been away from this site for a while so I don’t know
how much has been mentioned about eneloop batteries.
http://www.stefanv.com/electronics/sanyo_eneloop.html
I don’t have any vested interest in this company but
I do believe in reliable preps and these do it for me.
Batteries tend to die the longer they lay on the shelf.
These don't. Without going into boring details these
are what I feel are the best.
Long shelf life, the ability to recharge many times,
and being sold already pre-charged are among the
things that sold me on them.
The common size they make are AA. If you want bigger
they sell “shells” in C and D that you insert the AA’s
into.
Do some reading they may be worth your while.
JMHO,
Dan