Battery Life and Charge Time

The Galaxy S 4 features a removable 9.88Wh battery with 3.8V chemistry. The battery design is par for the course for any high end smartphone, but the fact that it's removable remains a staple of the Galaxy S design. Whether or not the bulk of consumers actually use the flexiblity offered by a removable battery is up for debate, but there's no doubt about the fact that Samsung has a strong following of users who appreciate the feature.

Unfortunately, only having access to the Sprint version of the Galaxy S 4 to review, most of our battery life tests on the cellular network aren't all that useful. The good news is that our WiFi tests should at least give you an idea of how well the SGS4 will compare to the HTC One when both are on the same network. We're using the latest revision of our smartphone battery life test to compare performance of all the key players here. 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 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.

As the most relevant comparison of platforms we have today, we'll start with the WiFi version of our web browsing test:

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

On WiFi the Galaxy S 4 falls behind the HTC One by an appreciable amount, however there's still an improvement in battery life compared to the Galaxy S 3. The Galaxy S 4's battery life isn't bad by any means, but do keep in mind that this is a large phone with a large display and a very powerful SoC. For much of the past year we've been talking about an increase in dynamic range in total platform power of high end smartphones and the Galaxy S 4 is no exception. Run it at full brightness or keep many cores running in their maximum performance states for a considerable period of time and you'll be greeted by a phone that's quickly in need of a power outlet.

As I mentioned earlier, we only have access to the Sprint version of the Galaxy S 4 at this point which unfortunately means that our 3G results aren't all that comparable to other devices here.

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

Even on Sprint, the Galaxy S 4 does surprisingly well.

Cellular Talk Time

Talk time is excellent on the Galaxy S 4, with the phone delivering effectively the same battery life as the HTC One. Without having to power on that huge display, the Galaxy S 4 can last for a very long time on a single charge.

WiFi Hotspot Battery Life Time

A combination of the Sprint network and the fact that the Galaxy S 4's display remains off during our hotspot test resulted in great battery life here as well. Again, this data isn't all that useful if you're not on Sprint but Samsung tells us we should be able to get our hands on an AT&T SGS4 in the not too distant future.

Charge Time

Samsung appears to implement Qualcomm's Quick Charge specification in the Galaxy S 4 and its bundled charger. I realize we haven't done a deep dive into what Quick Charge is and how it works, but I'll try to go through a quick explanation here. Most conventional chargers are linear, they take a fixed amount of input current (at 5V) and pass it along to the device being charged. The problem is that at deeply discharged states, the device's battery might be at a substantially lower voltage. A traditional linear charger won't change the current supplied based on the voltage of the battery being charged, and as a result can deliver sub-optimal charge times. When implemented, Qualcomm's Quick Charge technology can vary output current based on the voltage of the battery being charged, which results in less power being dissipated as heat and more being delivered to charging the battery itself. The table below helps illustrate the savings:

Quick Charge, at least in its currently available 1.0 specification, is still bound by the 5V limits of the USB BC 1.2 specification. The next revision of Quick Charge will enable higher voltage operation for even faster charge times.

Qualcomm Quick Charge 1.0, Theoretical Example
  Input Current @ Voltage Input Power Output Current @ Discharged Battery Voltage Output Power
USB BC 1.2 - Linear Charger 475mA @ 5V 2.375W 475mA @ 3V 1.425W
Qualcomm Quick Charge 1.0 475mA @ 5V 2.375W 700mA @ 3V 2.100W

The non-linear nature of Quick Charge significantly shortens charge time, particularly in the very early stages of charging when the device's battery is presumably fully discharged. As the device's battery voltage increases, current delivery tapers off and the QC advantage is no longer as great as a standard USB BC 1.2 solution. The end result though is significantly improved charge times.

The graph below shows the benefits of using Samsung's own charger vs. a standard charger that implements the USB BC 1.2 specification. When used with the bundled charger, the Galaxy S 4 recharges much faster than HTC's One, despite using a larger battery. Obviously the Galaxy S 4 will charge with any USB charger, but the charge time will simply be longer. Samsung uses a voltage divider and signals the presence of their own charger by sending 1.2-1.3 V across the D+ / D- pins, this is similar to what Apple does with 2.0 or 2.8 V across the pins for various USB chargers they've shipped over the years. This signaling is essentially Samsung's proprietary tablet charging signaling which they've employed on the Galaxy Note 2 and now SGS4, in fact the two use the same exact charger, so it's worth tossing out your old ones and getting the appropriate one to take advantage of the faster charging.

Device Charge Time - 0 to 100 Percent

 

Introduction & Design Galaxy S 4 - Powered by a Better Snapdragon 600 (APQ8064AB)?
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  • srihari - Thursday, May 23, 2013 - link

    Anand, non-technical people will not be able to judge the better phone by looking at the GPU benchmark onscreen numbers(with varying screen resolutions for different phone). so, i suggest you to post *only* GPU benchmark off-screen numbers. Reply
  • cadjak - Saturday, May 25, 2013 - link

    This device has a primary function that seems NOT to get examined in reviews. How well does it send and/or receive a simple voice communication? The S3 had some serious issues around reception in areas with marginal LTE signal. I have had to tweak mine to get it to reliably work as a phone, by setting it to CDMA auto (PRL). I am trying to find out if the S4 will have similar connection issues, but I'm not having much luck. Reply
  • vipuls1979 - Monday, May 27, 2013 - link

    i would sincerely like to go with Galaxy S4 rather then HTC one, updates released by Samsung are more quicker then HTC and
    did you know a recent Press Trust of India Release says Camera sales are down due to Smartphone camera
    full report at http://mobiknowhow.blogspot.com
    Reply
  • paul_59 - Monday, May 27, 2013 - link

    Interesting comments about differences between S4 8064AB &.HTC One 8064T

    I ran a custom kernel and overclock HTC One to 1.89Ghz (S4 1.9Ghz)
    Got sunspider 0.91 benchmark result 550 ms .

    I realise benchmarking is subject to lots of variables
    Reply
  • vipuls1979 - Thursday, June 06, 2013 - link

    Guys, i hope you must be aware of latest blackberry Q10 launched in India
    for more details visit http://mobiknowhow.blogspot.com/2013/06/blackberry...
    Reply
  • MonkeyK - Thursday, June 13, 2013 - link

    Are the battery test stats really right? 1 hour of additional Wifi web browsing time is huge. But every other review that I have read shows the S4 having slightly longer battery life. So what gives? Reply
  • elucid - Tuesday, June 18, 2013 - link

    I guess Part 2 is not coming? If it still is, a battery test with a real LTE network like Verizon (or even ATT) would be interesting. Reply
  • reapergato - Tuesday, June 18, 2013 - link

    2 months later and still no Part 2? I sure hope with all that extra real world testing the part 2 article will knock our socks off.... Reply
  • Optimummind - Sunday, June 30, 2013 - link

    It's been over 2 months and still no Part 2?

    Also, after re-reading the review, it seems the article has been edited from its original release.
    Reply
  • Streamlined - Sunday, July 21, 2013 - link

    Why did you use the 3rd gen ipad instead of the current model? Just because than Apple would have been at the top of every GPU chart? Reply

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