Battery Life and Conclusion

Battery Life

Smartphone battery life is going to depend greatly on screen brightness (and how the phone is used, of course), so we use a standardized test to compare battery life between devices. The battery test simulates constant use on Wi-Fi, with a realistic screen brightness (approx 180 lux; on the Zenfone 2 I had it set to two positions above middle brightness – auto screen dimming disabled).

The Zenfone 2 managed a very good 6 hr 40 min result here, within minutes of the Nexus 6 result. The Galaxy Note 4 provides a fantastic result here from its 3220 mAh battery, and is clearly better optimized in this area. In actual use I found the Zenfone 2 to provide a full day’s battery life, and didn’t need to charge it any more often than the Nexus 6 (which makes sense given the nearly identical result). This is based on my own usage pattern so your results will vary of course.

Quick Charging

As the $299 version of the Zenfone 2 includes a fast charger I was very interested in seeing just how this would compare to the Quick Charge 2.0 charging performance I’ve grown accustomed to with the Nexus 6.

The power brick is about the same size as Motorola’s quick charger, and offered very similar results as well. With the phone completely drained I was able to get a 100% charge in just under 2 hours (1 hr 55 min). Two hours to a 100% charge from 0% not only matches the performance of my Quick Charge 2.0 accessories for the Snapdragon-powered Nexus 6 and Moto X, but is a fantastic result in general.

The capability of charging so rapidly – especially the significant boost you’ll see from connecting it for just a few minutes – can change the way you use a phone. In my opinion all phones should offer quick charging of some kind going forward, and Intel and ASUS have a great implementation of it here.


I was extremely impressed with the Zenfone 2 overall, and after a couple of weeks of constant use I find that I could easily make this my daily driver. From the snappy processor to the fantastic touchscreen (with an excellent IPS display panel under it), it's a pleasure to use. The phone looks good with its understated style, and the ASUS ZenUI elements were pretty unobtrusive and added some nice functionality. The camera is only average, though it has a very effective low-light option that made a considerable difference in real-world use. Reception and call quality were excellent, and I had no trouble with the device in two weeks of use with my AT&T SIM, with excellent LTE data speeds as well. And finally, the phone was rock solid during testing with no crashes to report, which definately inspires confidence in this platform's stability.

But as impressed as I was with this Zenfone 2 as a smartphone, I was blown away by the phone as an unlocked, no-contract $199/$299 device. The nicest lower-cost unlocked phones I’d previously experienced were the two prior Nexus phones, with the $299 Nexus 4 and $349 Nexus 5 punching well above their class. But even Google’s Nexus has become a $649 off-contract behemoth (recently on sale for $499) that in some ways isn’t as good as this ASUS phone; the screen digitizer is better on the Zenfone, and the ASUS also doesn’t force device encryption like the latest Nexus, which makes the Nexus feel a little sluggish at times.

I think the sweet spot has to be the $299 version, as it doubles the system memory, quadruples storage, and adds an excellent fast-charging system for $100 more than the base model. But regardless of the version you choose, the ASUS Zenfone 2 is a great phone overall, and an absolute steal for the price.

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