Got my new Apple Watch Ultra earlier this week. Decided to test battery life. Wore 24 hours a day (I’ve used watches for sleep tracking for years,) unplugged at 100% at midnight Tuesday night/Wednesday morning and put it on for sleep tracking.

Wore it all day Wednesday, overnight Weds/Thu, all day Thursday, overnight Thu/Fri, all day today. It just went into power reserve mode at 11:40.

DOUBLE the claimed 36 hours battery life!