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
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  • Paulman - Friday, April 05, 2013 - link

    Now I can finally look forward to the next episode of the Anandtech podcast :P Reply
  • Brian Klug - Friday, April 05, 2013 - link

    Ha, heck yes!

    -Brian
    Reply
  • Bull Dog - Saturday, April 06, 2013 - link

    Yea I missed you on the last podcast. It just wasn't quite the same without (what I like to call) the "Klug rants." Reply
  • phillyry - Monday, April 08, 2013 - link

    Lookin' forward to it! Reply
  • leexgx - Thursday, April 11, 2013 - link

    i am very interested in this HTC One phone but i am also interested in the RAZR HD maxx as well but it does not seem to be much of an upgrade from the razr maxx i currently own

    issue i have is will it Really last an full day on one charge of real world use, as i have seen a lot reviews of phones and the battery life part of the reviews to me seem an Lie quoting Twice the real world battery life, yours included as well i got the HTC One X (uk) and it was an Joke to use as it would not stay on for long (only one that gets close to correct battery report is the razr Maxx and the Razr HD) only one site seems to side with poor battery life or currant smartphones correctly and that is "theverge" but other sites and other users do not like the site and tend not to agree with there results

    on the razr maxx that i own it can go nearly 2 days or 1 day if i go nuts on it, i really love HTC phones but with the Joke of an phone HTC one X (its like an portable gaming laptop your lucky if it lasts 2 hours on battery) that got rid off in less then an month of owning it, every phone i have had has been poor battery life, i had the G1 and HTC desire (the first one) but i could use an extended battery on them yes it made them an brick but it lasted long time

    i do really like HTC phones but as all other smart phone makers are doing still is neglecting the battery size so it can Just about make it last an day if you use it lightly
    Reply
  • leexgx - Thursday, April 11, 2013 - link

    but to add this is an running battery life with any one person i have come across who has got smart phones Reply
  • henrybravo - Thursday, April 11, 2013 - link

    Is the period key broken on your keyboard? Nothing but run-on sentences. Reply
  • leexgx - Saturday, April 13, 2013 - link

    was bit long my bad, just i find battery tests that sites do seem to be more then half what is reviewed as to why i norm just divide it by 2.3x ish to get real world results

    there needs to be a real world tests as well (facebook, twitter, skype, youtube, browsing so on), as there is no way you can get the times you see on review sites (HTC one X international version and the iphone is good example of unrealistic battery life is when reviewed)
    Reply
  • Thud2 - Sunday, April 14, 2013 - link

    Interesting that you acknowledged that you had not punctuated your post you then made another post and again you didnt use punctuation it is interesting i was going to ask you why you did it i have decided not to do that that would be redundant i am of the opinion that you are going to continue to post this way as a result of that i am going to disregard your posts in the future . Reply
  • sosrandom - Monday, April 15, 2013 - link

    at least ieexgx has punctuation in his sentences, anybody should be able to tell when a sentence starts and ends without thinking about it Reply

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