Battery Life and Charging

Battery life is one of those things that consistently ranks among the highest in consideration for a mobile device. At the same time, OEMs still seem largely unwilling to double or triple battery capacities between generations, or go the Motorola route and offer two different models with double capacity. The story of smartphones is again this continual competition between everything and the industrial design.

With the One, HTC has gone again to its pyramidal stack of display, then battery, then PCB. The result is the familiar curved backside from where the PCB sits, and a large, thin battery sandwiched between the display and PCB.

The HTC One moves to a 2300 mAh, 3.8V (the higher nominal chemistry that everyone has moved to) lithium-ion polymer battery, giving it a capacity of 8.74 watt-hours. It’s obviously internal and not easily user-replaceable. Of course, battery size doesn’t entirely dictate battery life, it’s just a larger electron tank to draw from. What ultimately is a more interesting is how efficient the platform is which draws from it.

The thing about HTC and battery life specifically is that as of late they’ve been penalizing themselves on the display side of things, which is the single largest consumer of power in a device. A number of other OEMs artificially clamp display brightness just to set a better higher bound for battery life, and for example HTC’s display auto brightness function doesn’t have as much dynamic range as the slider being actuated manually. The result is a phone that’s brighter than it needs to be a lot of the time. On the software side HTC does have system optimizations that do things like batch up network traffic so that the phone isn’t going into a constant cellular connected state and burning power for an app written by a developer who doesn’t know anything about cellular connection state tables, and strategies like suspending the cellular data connection when on WiFi or when the phone is in standby for long periods.

To find out where the HTC One sits in the battery life spectrum, we turn to the newest version of our battery life test. This is now our sixth revision of the battery life test, and we feel is the optimal balance between challenging workloads and idle time. The basic overview is the same as the previous test — we load webpages at a fixed interval until the handset dies, with display set at exactly 200 nits as always. Power saving features (in this case the HTC Power Saver) are disabled if they turn on automatically, and background account sync is disabled. The test is performed over both cellular data on all available air interfaces and over WiFi in an environment with good signal levels. The new test has decreased pause time between web page loads and added a number of JavaScript-heavy pages. I sat down with some UMTS RRC (Radio Resource Control) emulator tools and also made sure we had a good balance of all the RRC states (DCH, PCH if possible, FACH, IDLE) so we weren’t heavily biased towards one mode or the other.

I’ve included the HTC DNA in the fray as well since I’ve had those numbers for a while. Let’s start with the WiFi test, where we attach the device to a dedicated WiFi network with no other clients.

AT Smartphone Bench 2013: Web Browsing Battery Life (WiFi)

The One includes the newest BCM4335 WiFi/BT/FM combo from Broadcom, which is still built on a 40nm process. For the purpose of the battery life test I attached the One to the same AP as I’ve always used, however I will repeat with my 802.11ac AP in due time to see whether the shorter duty cycle afforded by a much higher PHY rate makes any difference.

AT Smartphone Bench 2013: Web Browsing Battery Life (3G/4G LTE)

On cellular data the One isn’t bad at all, looking at the 3G result from final hardware and final software. I consider this pretty good all things considered for the HTC One, and mirrors my experience.

Cellular Talk Time

On cellular talk time the One really shines, coming in well ahead of almost everything else. This is an impressive result.

WiFi Hotspot Battery Life Time

As a hotspot once again we have great battery performance. This test consists of four of the page loading tabs running on an attached notebook in addition to 128kbps streaming MP3 audio being played on the device. This is a challenging test that results in the cellular connection being lit up almost constantly, and isolates out display.

My subjective impressions using the HTC One as my personal device are that battery life is quite good, and moreover that the DNA battery life also was better than some other phones people had no problems with in 2012. I have yet to have an issue making it through an entire day on the HTC One, even when aggressively using the camera. If I knew I was going to be away from the charger for a long time, I did enable the power saver, which sets max CPU clock on the Snapdragon 600 to around 1.3 GHz in addition to lowering brightness a little bit, and a few other things as shown in the previous screenshot. In practice I really don’t notice much of a performance difference with the power saver box checked unless I’m really looking for it, but this probably dumps the SoC into a better voltage state to say nothing of how much lower active power is.

Charging on the HTC One takes a little while longer than I’m used to for other devices. I get lots of requests to do charging tests and have been running them on everything I can lately, but anything power related remains an involved process. To test the best case charge time, I have a dedicated power supply voltage limited to 5V and capable of supplying a lot of current. I emulate the USB BC1.2 charging spec on a breadboard and connect USB to the device, then time how long it takes to charge devices completely. I plug the phone in after it dies running our battery life test, and time the amount of time from that fully dead, won’t-turn-on state to fully charged, either with a green LED or when charge current goes to zero for devices without a charge status LED.

Device Charge Time - 0 to 100 Percent

The HTC One definitely takes a while to charge. What’s interesting however is that the charge curve gets the One to 85–90 percent under the normal 3 or so hours, it’s that last ten percent that takes forever. I also have confirmed that Qualcomm’s Quick Charge is not being used on the HTC One, for whatever reason, possibly to maximize compatibility with the portable USB battery chargers that are now proliferating. The PMIC is there, it just isn’t enabled. My guess would be that HTC wants to prioritize battery longevity and minimize any even potential extra wear since the battery on the One is sealed inside.

Hardware (Continued) and Cases HTC's Ultrapixels - Bucking The Trend


View All Comments

  • comomolo - Saturday, April 06, 2013 - link

    In no way Class 10 SD cards are stuck at 10MBps. That's just the minimum.

    I'm simply not buying a non-expandable phone. The same with battery. I'm not the kind of person who changes devices every two years. I just had an iPhone 3G battery die on me and I swear I'm never going to experience that again. In a couple of years, 128GB very fast SD cards will be cheap.

    I also dislike physical buttons. I think Google is right putting them inside the screen and both Samsung and HTC are wrong putting them outside it.

    Finally, all this trouble to get through metal seems pretty silly to me. Coloured polycarbonate (Nokia N9-like) is my first choice regarding materials.

    I'm definitely no the target for this phone.
  • thesavvymage - Sunday, April 07, 2013 - link

    xperia ZL has a micro-sd slot and has on screen buttons :) Reply
  • MobiusStrip - Sunday, April 07, 2013 - link

    On-screen buttons suck because you have to look at the screen and poke at them, whereas physical buttons can be felt and operated without looking. Reply
  • Nuren - Monday, April 29, 2013 - link

    HTC just released the One here in China. It's exactly the same awesome phone but has a removable back with dual-sim card and SD-card slots. I still use my 2007 iPhone with its original battery and it still works fine. I love my Nokia Pureview 808 with it's lovely and tough polycarbonate (plastic) body. The plastic of Samsung phones is real cheap-looking and crappy, and easily damaged. I had a Samsung Note that I got rid of whilst still keeping my antiquated iPhone. This review has convinced me to get the HTC One instead of waiting forever for the iPhone 6, which I seriously doubt will be better than or as innovate as the HTC One anyway. And I must express my gratitude for the most thorough and thoughtful phone review that I have ever read to date. Reply
  • darwinosx - Tuesday, April 30, 2013 - link

    You are wrong about card speed. Ask Brian. Reply
  • eebrah - Tuesday, April 09, 2013 - link

    If you have to remove the cover in order to access the MicroSD card then they have designed it somewhat poorly, that is not the case with all microSD equipped phones.

    That being said, It is unlikely that one will be constantly removing and switching microSD cards, hence the inconvenience of removing the back cover once every few weeks for whatever reason may be justifiable.

    The higher capacity versions of these phones come at a SIGNIFICANT premium, you may not feel like it is an issue to you but for others it may be when compared to the cost of acquiring a similarly sized microSD card.

    USB OTG cables are fine .... when copying files, but not when you wish to have the expandable storage with you at all times e.g music playlist? It would just make holding and carrying the device awkward and increase the chances of doing damage to the device when compared to microSD card.
  • augustofretes - Sunday, April 07, 2013 - link

    The developer edition costs $649 and is 64GB, game set and match. That's my next phone. Reply
  • darwinosx - Sunday, April 07, 2013 - link

    Yeah thats a deal. Any word on when they are selling these? i assume developer edition means you don't have to root it.. Reply
  • darwinosx - Sunday, April 07, 2013 - link

    The carriers know that very, very few people ue SD card slots. Google doesn't like them either and never has. Reply
  • FITCamaro - Monday, April 08, 2013 - link

    It has nothing to do with Google or manufacturers not liking them. It is application developers that don't like them. Apps being stored on SD cards means easier piracy. That is why Apple has never allowed removable storage. And application developers love them for it. Google and Microsoft are moving more this direction to appease developers. Reply

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