The Microsoft Lumia 640 Review

Battery Life

One thing I distinctly remember about the Samsung Focus is much of an improvement the battery life was compared to the original Galaxy S. Windows Phone 7 was a very well tuned OS, and it managed battery life very well. When the first waves of Windows Phone 8 devices were launched, I heard complaints about battery life, and I was very surprised. The Lumia 930 review here at AnandTech confirmed that there were issues with battery life on at least some Windows Phone 8. However, the Lumia 735 achieved a very respectable battery life in our web browsing test. With both of those results in mind, I was very curious about how the Lumia 640 would fare when it comes to battery life.

As always, our first test is the WiFi web browsing battery life test. Since this Lumia 640 is locked to Cricket Wireless, I'm unable to also test it on LTE, which is unfortunate. However, Qualcomm's radios have evolved to the point where there's only a very small difference the between power usage with a good LTE signal and WiFi.

With a 9.5Wh battery and Snapdragon 400, I had expected the Lumia 640 to last much longer in this test. It shares many components with the Lumia 735, including the SoC, yet the Lumia 735 lasts significantly longer. I can only attribute this to display power usage, and even that seems strange as the Lumia 735 uses an OLED panel which will consume a lot of power when displaying the large white areas of web pages. To ensure there wasn't any sort of issue, I re-ran the battery test and achieved roughly the same result. 8 hours is not the lowest result we've seen, but it's ultimately disappointing when you consider how long other budget devices like the Moto E can last.

In GFXBench's battery test we see that the Lumia 640 sits between the Lumia 735 and the Moto E. However, it should be noted that although these three devices achieve a much longer battery life than other devices, this is a result of their relatively low performance during GFXBench T-Rex HD.

One observation that doesn't show up during out battery tests is idle battery life. During my time with the Lumia 640, I noticed that Windows Phone seems to have an abnormally high battery drain when devices are idle. Even though I was only able to use it on WiFi and had no cellular connection when I wasn't at home, I still found myself having to charge it in the early evening. The Lumia 640's battery life is certainly better than devices like the ZenFone 2 and Lumia 930, but it definitely doesn't compare to the Moto E and the Moto G.

Charge Time

The Lumia 640 ships with a 5V, 0.75A charger. This is a lower wattage than the 5W chargers that ship with most phones, and it's significantly lower than the high power chargers that are now reaching as high as 18W. Something worth noting is that at least with the North American Cricket Wireless version I received, the cord on the charging block is permanently connected, so you can't separate the block and the cable like on most devices.

With its relatively slow charger, the Lumia 640 has a fairly long charge time. It's actually the fastest of our group of low end devices though, with the Moto E being noticeably longer, and the Lumia 735 being substantially longer at 5.57 hours. Not including a super fast charger is obviously done for cost reasons, but I do wish these devices would ship with at least a 5W charger. Thankfully, if you do have 5W charger it will charge the Lumia 640 faster than the one included in the box.