i built my own camera out of a Zero 2W [0] and by disabling Picam2 and letting the OS (Debian Bullseye) idle, i can get 2 days of shots and some videos while i walk around the city/hiking out of 3 18650 batteries... bringing 3 spare batteries in my backpack never put me needing battery in any situation! starting Picam2 takes a fraction of a second