Apple Watch Ultra 4 Adds 50-Hour Battery and 0-10 Readiness Score as HR Claims Face Scrutiny
Updated
Updated · DC Rainmaker · Sep 17
Apple Watch Ultra 4 Adds 50-Hour Battery and 0-10 Readiness Score as HR Claims Face Scrutiny
3 articles · Updated · DC Rainmaker · Sep 17
Summary
Apple’s Ultra 4 review finds the biggest gains in a new heart-rate system, a 0-10 Readiness score and on-device audio tools, while battery life holds at about 50 hours in normal use.
A new S11 chip and redesigned optical sensor drive more frequent health sampling—background heart rate every 5 seconds and HRV every 5 minutes—feeding Vitals trends and the new daily readiness metric after 7 nights of data.
Real-world testing said the heart-rate sensor is Apple’s best yet, but challenged Apple’s 1,400-person study because missing workout data points were excluded, making the “most accurate wearable” claim hard to verify.
Workout battery tests came in near Apple’s 20-hour GPS claim, with new modes stretching GPS life to 25 hours in Extended mode and 45 hours in Max Extended mode.
Two audio features are live now—sound recognition and instant wrist-raise Shazam—while Live Rewind, Siri Recap and a redesigned Health app are due later in 2026.