Apple Watch Series 12 Sensors: How Much Do They Drain the Battery?

The Apple Watch Series 12 and Ultra 4 use larger sensors that check heart rate every five seconds and heart rate variability every five minutes, far more often than earlier models. A Macworld test compared a Series 11 and Series 12 during a seven-hour hike, splitting time between power-saving and normal workout modes. The one-day telemetry can only suggest a trend, not a definitive conclusion, about the battery impact.

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The Series 12 and Ultra 4 use bigger sensors and sample heart rate every five seconds, compared with every five minutes on earlier models. Heart rate variability is checked every five minutes rather than every two hours. A Macworld comparison placed a Series 11 on one wrist and a Series 12 on the other during a seven-hour hike, with power-saving mode for the first half and normal workout mode for the second.

Telemetry was logged every 15 minutes, yielding 60 points from 8 a.m. to 11 p.m. The Series 12 has a 1.461 Wh battery at 100% capacity, or 14.61 mWh per percentage point; the Series 11 has 1.403 Wh at 98%, or 13.74 mWh per point. After the workout, the Series 12 showed more background activity, yet energy use differed only slightly.

Count words: first para: The(1) Series(2) 12(3) and(4) Ultra(5) 4(6) use(7) bigger(8) sensors(9) and(10) sample(11) heart(12) rate(13) every(14) five(15) seconds,(16) compared(17) with(18) every(19) five(20) minutes(21) on(22) earlier(23) models.(24) Heart(25) rate(26) variability(27) is(28) checked(29) every(30) five(31) minutes(32) rather(33) than(34) every(35) two(36) hours.(37) A(38) Macworld(39) comparison(40) placed(41) a(42) Series(43) 11(44) on(45) one(46) wrist(47) and(48) a(49) Series(50) 12(51) on(52) the(53) other(54) during(55) a(56) seven-hour(57) hike,(58) with(59) power-saving(60) mode(61) for(62) the(63) first(64) half(65) and(66) normal(67) workout(68) mode(69) for(70) the(71) second.(72) Good.

Second para: Telem