Wesley's Tool-Box

Even with excellent performance, lackluster battery life will tarnish the usability of a phone. It's thus natural to see if iPhone 5S has made any improvements with battery usage from the previous generation. Apple has targeted it to be at least as good as iPhone 5, so I wanted to see how the two really compares in real life use.

The official capacities are 5.45Wh (3.8V 1440mAh) for iPhone 5 and 5.92Wh (3.8V 1560mAh) for iPhone 5S, an 8.6% difference. So 5S could use a little more power and still stay even. The iPhone 5 I have has seen use for about two months, while iPhone 5S has been with me for a month. So both have relatively fresh batteries close to these original capacities.

With these in mind and full charge, I started using the two devices, which were running iOS 7.0.3 now, in the same manner throughout the day. This meant opening the same app and taking the same actions at the same time. It's an interesting experience, and because apparent responsiveness of the two devices are similar at casual use, it wasn't too difficult to carry out.

To even the playfield further, push notifications, push data and automatic app updates were disabled, while screen brightness was fixed to 33%, which is good for indoor use. WiFi and Bluetooth were both enabled, but not used, so LTE was responsible for data. Other settings like GPS and visual effects were kept on by default. So how did the draining of the battery turn out?

The iPhone 5S was able to consistently outpace iPhone 5 by a small margin. In the early hours, there was about 3% points difference between the two, which was widened to about 6% by the late hours. The steep drops happened when I was doing a combination of web surfing, app downloading, map browsing, music streaming, and photographing. The sharpest drop in the late hours were attributed to playing 3D games. Slow drops were when the phones were mostly idling in my pockets.

In the end, iPhone 5 lasted 12 hours and 20 minutes when iPhone 5S reported 10% battery charge left. iPhone 5S was able to keep surfing the web for 48 minutes more, shutting down at 13 hours and 8 minutes mark. So it seems that 5S has similar power consumption levels to 5, and the extra battery capacity is being used to let the user use the phone nearly an hour more in casual use.

But if the battery holds more charge, would it take more time to charge it back to full capacity? I took a look at this as well.


I used an official Apple 10W USB charger that came with an iPad to let the phone charge at its full speed. Up to about 75% charge, both phones were able to charge about 1% point every minute. This means it's charging at roughly 3.3W assuming 100% efficiency. The reality is more like 85%, so it's close to 4W, or 800mA at 5V. This is higher than USB 2.0's 500mA standard, but within USB 3.0's 900mA standard.

After 75% point, though, the two phones divulge a bit. iPhone 5S was able to keep going at the same speed for 10% point more, while iPhone 5 started to slow down. Beyond 90% point, both phones trickle charged at about 1% point every 5 minutes until the battery was full. In the end, iPhone 5S finished charging in 2 hours 14 minutes, while iPhone 5 took 2 hours 30 minutes. Even with higher capacity, 5S charged slightly faster, so the answer to my earlier quesion is no.

Your mileage may vary, but I can say that iPhone 5S should give you no worse battery performance compared to iPhone 5, regardless of what you do with it. So take comfort in the fact that the amazing performance improvements don't come at a penalty. With this test done, I think I've touched on all the major points of the new iPhone 5S. The mobile carriers in Korea has just officially started selling it today, so I hope you can use my write-up to make an informed decision.