Best in cold
The only AAA that still works at −15 °C
Energizer Ultimate Lithium AAA
Lithium AAA, rated to −40 °C, ~1/3 lighter than alkaline
Alkalines lose most of their usable capacity in real cold and a headlamp dies mid-descent; lithium does not, and it costs roughly three times as much per cell.
Holds voltage in the cold, which alkaline simply does not
A third lighter than alkaline
Ten-year shelf life — buy once, use across trips
Expensive per cell
Some airlines limit loose lithium cells — carry them in the cabin, taped
Not rechargeable
Not for you if: Low-altitude treks in warm months. Ordinary alkalines are fine below 3,000 m.
Check price on Amazon