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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  • danbob999 - Thursday, April 25, 2013 - link

    Glasses are fashion accessories. You don't choose a specific model because it is more powerful or will give you better vision. You choose a model because it looks good. Reply
  • UpSpin - Thursday, April 25, 2013 - link

    I need glasses. And I choose the model which not only gives me better vision, but perfect vision. You can choose between glass or plastic, with adaptive dimming in sunlight, a flexibel titan frame, or a huge bold hipster frame, with large or small glasses, with color enhancements, polarisators, AR coatings, ...
    If I had perfect eyesight, I wouldn't choose any model at all, so I only buy it because I need it, not because it's a fashion accessory, but this doesn't mean that the glasses I buy must look ugly as hell. I choose the model which fits to my person.
    The same with watches. I had a watch, because I had no mobile phone but wanted to know the time. Of course did I choose the watch which had the functions I wanted at a reasonable price and which looked the best for me. We're not talking about Rolex, or whatever, but the useful traditional watches (in my case Casio).
    The same with smartphones. And here again do we also not talk about Vertu, etc. but a competive priced high end smartphone, which, even with all those features, can and should still look good, especially if it costs +$600.
    Reply
  • danbob999 - Thursday, April 25, 2013 - link

    You are talking about the lenses. With any model of glasses you can get lenses which will give you perfect vision.
    The glasses themselves are fashion accessories.
    Unlike your glasses and your watch, a smartphone isn't a fashion accessory. You wouldn't pick a phone just because it looks good. Specs are the most important things to consider. At least that's what I expect on a tech site. If I wanted to know which phone looked the best I woul be reading fashion magazines instead.
    Reply
  • UpSpin - Thursday, April 25, 2013 - link

    I think you try too hard to justify that design isn't important for you. I'm not a native english speaker, so I assumed that the meaning of glasses is the whole lenses+frame (dictionary confirmed this), just as the meaning of smartphone is the whole thing, not just the electronics or the casing. Now you reduced it to glasses frame, fine, but this makes absolutely no sense, because you always have to buy and use both and the frame can't be freely choosen either. Some frames only support glass, some require plastic lenses. Some frames only work for thin lenses some people with bad eyesight and thick lenses have to use other frames. You pick what both suits your needs and looks good on you. The same with a watch, the same with a car, the same with a smartphone the same with everything you spend money for. Both design and specs go hand in hand.
    Or would you like a 1kg heavy, 10cm thick smartphone if you don't care about design? What's design and what's specs for you?
    Again: At such a high price point it should look and feel great, too, thus design is important, too. Sure, if the specs are crap, then the best design is worth nothing. But the HTC One specs aren't crap, they are on par with the S4. And it's a fact that the S4 looks like the S3, and both look like all the other cheaper Samsung smartphones, and all of them have a highly glossy finish which looks, for me, very cheap. So the specs are great, but it just doesn't look like it.
    Reply
  • danbob999 - Thursday, April 25, 2013 - link

    Most glasses can be paired with any type of lenses. I am sure you understood my point. Going back to phones, I do care about design. I care about size and weight. I care about the resistance of the phone (if I drop it). I care about the placement of the buttons. I prefer hard buttons than capacitive ones. All these are part of the design. I just don't care how it looks, and even less how it "feels". I knew schoolgirls cared about the look of their phones but I didn't imagine so many people cared about it on a tech site. It's beyond me. Did you also choose your home phone or your TV based on their look? Did you really tell yourself that you can't buy that $2000 TV because it looks like a black rectangle which looks as cheap as that $500 TV next to it? At least home phones and TVs constantly in sight, and not hidden in your pocket most of the time. Reply
  • TedKord - Thursday, May 02, 2013 - link

    Lenses are custom ground and fitted into the frames you choose. You can literally get most any lenses in any frames (except if your vision is so bad it requires super thick lenses, then you may have limitations on what frames you can pick)

    I've gone through this with my daughter, who has 20/200 vision. I've been lucky so far - while the rest of me is falling apart, my eyesight is still 20/18.
    Reply
  • mrochester - Friday, April 26, 2013 - link

    Personally I don't see why as a consumer I can't have both functionality AND looks. Apple and HTC show that you can have both, so I don't see why I would settle for an S4 when I already have an iPhone 5. Reply
  • danbob999 - Monday, April 29, 2013 - link

    The iPhone 5 doesn't have the functionality of the S4. It's more to the level of the S3, 6 months late to get that shiny metal box.
    The One is a good phone but it does make some compromises in order to fit metal. These compromises are SD card, battery capacity and replaceability, overall phone size, included sensors, and even a little CPU speed. The S4 even supports more LTE bands (T-mobile's version supports 6 different ones)
    Reply
  • TedKord - Thursday, May 02, 2013 - link

    It depends on which you value more. I'll take functionality/versatility over aesthetics any day, so I chose the S3 over the 4s/5. I would choose the S4 over the 5/One simply because it still has expandable storage and swappable battery, and Samsung releases source/updates much better than HTC. (I've got my S3 in a Seidio Active Extended case, so you can't even tell it's got a plastic back. Plus, I can get an aluminum back for my S3 for $10 off Amazon, if the plastic bothered me - but I prefer to keep the stronger signal) Reply
  • TedKord - Thursday, May 02, 2013 - link

    But many people DO choose a smartphone based solely on looks, or what others own. Probably not the folks in forums like this, but they're a small minority. The general public is sold on shiny and pretty. Reply

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