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Why Has The iPhone 4S’ Standby Time Dropped?

Here’s a puzzle: where, or how, did the iPhone 4S drop 100 hours’ standby time? According to official figures on Apple‘s site for the phone, it has a standby time of 200 hours (that’s 8 days and 8 hours). That’s a long time. But it’s much less than the 250 hours quoted for Apple’s first effort at its own phone, the iPhone in 2007 – and it’s far less than the 300 hours given for the iPhone 3GS and iPhone 4. (See the iPhone comparison page on Apple’s site.)

Other battery life figures quoted by Apple (NSDQ: AAPL) marketing chief Phil Schiller during his presentation at Cupertino included lots of data about the new phone (on which the new Siri voice assistant is impressive), and its battery life: 8 hours of 3G talk time, 14 hours of 2G talk time, 6 hours of WiFi 3G browsing, 9 hours of WiFi browsing.

Other battery life statistics for the iPhone 4S’s battery life – 3G talk time, 2G talk time, 3G internet browsing, video playback – are the same or better, apart from the WiFi browsing, which is given at nine hours for the 4S, and 10 for the iPhone 4.

Here’s the historical data (and the spreadsheet is below).

iPhones' battery life compared

For comparison, the Samsung Galaxy S II standby time is given as 710 hours on 2G and 610 hours on 3G standby. Samsung also gives talk time as 520min (8hr 40min) on 3G and 1100 minutes (18hr 20min) on 2G. It’s hard to know exactly how comparable they are: Apple’s tests, given on its battery test page, suggest that its standby configuration has Wi-Fi on: “All settings were default except: Wi-Fi was associated with a network; the Wi-Fi feature Ask to Join Networks was turned off.” Samsung doesn’t explain how its tests are done.

While 200 hours is a long time (and 710 hours very much longer), the reality is that nobody gets the battery life promised in specifications like these. But they’re often indicative – so you might expect that this will indicate a notably shorter battery life for the iPhone 4S. (We will try this out in later tests.)

So what’s changed? I did ask Apple – repeatedly – but it had no response.

Might it be the dual-processor A5 chip that’s being used to power it? In the replay on Apple’s site, Schiller talks about battery life at 58:20. Speaking about the inclusion of the dual-core A5 chip in the phone, he says: “You would think if you put a processor that powerful inside a super-thin phone, one of the things you’re going trade off is battery life – but the hardware and software teams have worked really hard to get industry-leading battery life as well.”

He then cites statistics for the battery life on various activities – but doesn’t mention standby time.

It’s possible that powering the two cores, even in quiescent mode when the phone is just waiting for a call, is what uses the power. Possibly it’s that the Siri natural language parsing system, which is activated when you lift the phone or speak directly to it, is using enough power in the background to shorten the life. (You can turn Siri off; it will be interesting to see if this makes a difference.)

Or, alternatively, possibly it is the iOS 5 software, which was still under development when the phone would have been prepared. Some developers have indicated that the iOS 5 software is “hefty on the battery”, or was until very recent builds. But there’s no consistency there; some said they were seeing exactly the same battery life.

Possibly there’s some bugs to be worked out of the iOS 5 software, which we understand has now gone GM (Gold Master), and is officially released on 12 October.

But for now, without a response from Apple, and without anyone having one in a reviewer’s hands, there’s no simple answer. The claimed battery life is shorter. Why? It’s a mystery.

Here is the data confirming the graph:

(Updated to correct 3G browsing time.)

This article originally appeared in MediaGuardian.

One Response to “Why Has The iPhone 4S’ Standby Time Dropped?”

  1. My bet is GPS usage for the reminders…. Wouldn’t this cause regular GPS chip usage that didn’t exist before? While the phone is idle, it must be aware of where it is…