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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  • airspoon - Sunday, June 23, 2013 - link

    Believe it or not, some people actually do consider phones to be a fashion accessory -obviously, because that is what the guy is saying. He is telling you that he does, in fact, consider a phone to be a fashion accessory. I happen to agree with you that it is silly and function before form is certainly motto for smartphones, but unless the guy is your employee then it shouldn't matter to you how he chooses his phone. It's one thing to argue OUR opinion that function beats form in the phone department, but you can't really make a reasonable argument that HIS phone is not a fashion accessory.

    With that said, the function of a non-unibody plastic chassis beats the form of a unibody aluminum chassis any day. Not because it may or may not provide increased sturdiness or less weight, but rather because it allows you crucial access to the battery compartment and storage I/O. Obviously, a unibody chassis cannot provide said access and a non-unibody aluminum chassis would be far too bulky and a lot less sturdy. In fact, a non-unibody aluminum chassis is simply not feasible in a premium phone worth anything. The fact that I can remove or replace the battery and add an SD card is well worth the plastic to me (and I'm sure the vast majority of S4 owners). The benefits of plastic far outweigh any perceived drawbacks. However, those who choose phones based SOLELY on its fashion statement rather than functionality -would obviously prefer the unibody aluminum (as it does arguable look and feel better). Personally, I like the look and feel of the unibody aluminum shells and if the plastic body of the S4 didn't offer the tremendous functional advantages that it does, then I would much prefer an aluminum unibody. However, the ratio of function to form of the S4's plastic non-unibody chassis makes it a "no-brainer" in my opinion. I sure hope Samsung doesn't cave in to the pressure and go aluminum unibody in the S5 to appease the vanity seeking consumers because Samsung would have to sacrifice major function to do so. I like being able to instantly add 64 gigs of storage in an interchangeable medium. I like being able to carry around a spare battery and not have to worry about carrying around a USB cable and looking for a usable plug when I'm traveling or out on the town. I like the peace-of-mind in knowing that the life expectancy of my phone is not dependent on the cheapest commodity batteries that the telecom company could secure. To me, that is well worth the plastic non-unibody design. Again, the function far outweighs the form -even for those who value form.
    Reply
  • speculatrix - Sunday, April 28, 2013 - link

    I'm a form-follows-function person but I agree with Upspin

    If you're paying quite a few hundred for a phone then you want it made of premium materials and to not be ugly.

    Provided the style and materials don't affect performance, which the iphone4 suffered.

    I have a note 2 and would prefer if it had more metal in the outer frame to make it tougher. But I am pretty sure RF performance would suffer if it was totally metal backed.
    Reply
  • danbob999 - Monday, April 29, 2013 - link

    Metal wouldn't make it tougher. Nobody change its phone because the plastic broke. People change phone because it is too old or because the display is broken.
    You want metal either because you think it looks better, or because it will look more expensive and you want people to know you have an expensive phone.
    Reply
  • patlak - Saturday, May 18, 2013 - link

    So, all these people that buy Mercedes and BMW are dumb? Why should they cash out 20 grand extra when they can just buy a Kia that provides the same functionality as a car, but also with similar engine power and capacity for much much less. Since you sit inside the car all the time, just like your phone sits in the pocket, why would you bother with the premium look. Reply
  • TedKord - Thursday, May 02, 2013 - link

    There's nothing wrong with desiring a product look the way you prefer. But using the glasses analogy, which would you buy? The really stylish pair that doesn't fit your head/nose and only corrects your vision to 20/50, or the ugly pair that fits perfectly and gives you 20/20?

    I know there are more choices, this is just an example to fit the current discussion. I love the HTC One (especially the front speakers), but I'd have to choose the Galaxy S4 (if I really needed a phone right now). The microsd slot and swappable battery are important to me, and Samsung is much better at updates and releasing source for devs. I choose function over form.

    Now, I really wish HTC would at least add the built in kickstand back in. That was a great little touch they had for a while.
    Reply
  • dyc4ha - Wednesday, April 24, 2013 - link

    lol look at all the designer labels, appearance matters in real life I assure you. Reply
  • MrSpadge - Thursday, April 25, 2013 - link

    He didn't say he would. Reply
  • Reikon - Wednesday, April 24, 2013 - link

    Is it that hard to realize that a lot people don't actually use cases for their phones? Reply
  • darwinosx - Wednesday, April 24, 2013 - link

    I never use a case. Lots of people don't. Quit making excuses for Samsungs cheapness. Reply
  • Notmyusualid - Wednesday, April 24, 2013 - link

    Exactly - mine won't see a case at all.

    I wanted to hold out for my removable battery & SD slot, but since my SGS2 had such poor audio, (thus meaning I often missed calls in a noisy communications / server environment), I gave in, and my new HTC One will arrive tomorrow.

    I might have lived with the plastic though, I had no case on my SGS2, and loved how light it was.

    A 4" version of either the SGS4 or HTC One with no skimping on internals would have me jumping for joy though...
    Reply

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