Being far from a cell tower would also place a lot of stress on the battery, so hiking by itself is probably more draining than you'd expect
TheDong, can you test if putting it on air plane mode makes any difference? Maybe you're on the edge of multiple cell towers and your phone is trying to connect/disconnect too aggresively?
Congrats on somehow having a better battery life; all the mini users I know can't manage an 8 hour day with theirs without plugging in somewhere.