One of the chief differentiators with the Samsung Galaxy S 4 versus other current flagship Android devices is the continued support for user-replaceable batteries. Although removable batteries are becoming increasingly scarce as industrial designers prioritize aesthetics and thinner profiles, being able to swap batteries or substitute in a larger one is still an added convenience if you absolutely need it.

I’ve been carrying the Samsung Galaxy S4 Google Play edition (henceforth SGS4 GPe) alongside the HTC One GPe since getting the two devices, and while I have a Mophie Juice Pack for the HTC One, I didn’t really have a bigger battery solution for the SGS4 GPe. Probably my biggest use case for extended batteries is when I’m traveling, where having a bigger battery often is the difference between being able to relax and searching for an outlet in a terminal. When I saw the ZeroLemon 7500 mAh battery mentioned on Reddit’s r/android and instantly knew I wanted to give it a try and put it through our battery life and charge test routine.

First, the ZeroLemon 7500 mAh battery is considerably bigger than the stock SGS4 battery, which came in at 2600 mAh. Both are 3.8V nominal chemistries, so that works out to 28.5 Whr for the ZeroLemon, and 9.88 for the stock one, a scaling of 2.88 in battery capacity. Because energy density doesn’t change between the two (fundamentally it’s still the same 3.8V Lithium-Ion polymer), the extended battery achieves its larger capacity by increasing volume. As always, this is the tradeoff that industrial designers have to make – increasing battery capacity at present necessitates more volume dedicated to it.

The extended battery is really two pieces. The first is shaped like the stock battery and fits inside the housing, the second seems to be two larger cells above it which protrude from the back of the SGS4. As a result, the extended battery requires a different kind of battery cover entirely.

The ZeroLemon’s battery cover isn’t so much a door as it is a rubberized case that fits on and wraps around the SGS4. It covers the volume rocker and power buttons, and imparts a somewhat squishy feel to them. There are also holes for the microphone, headphone jack, IR Tx/Rx port, and at the bottom microUSB and speakers. The rear facing speaker on the SGS4 gets covered up somewhat, although sound still leaks between the battery and chassis and out the grille at the bottom. The far bottom of the battery does somewhat occlude the lower primary Tx/Rx antenna on the SGS4, although I haven’t seen a dramatic change in RF performance.

Obviously the weight and size of the SGS4 changes with the case and extended battery installed, the question is how much. The tradeoff with the bigger battery is that the SGS4 gets considerably bigger, but not unwieldy so. It’s a big phone for sure though.

Samsung Galaxy S 4 Extended Battery
Battery Stock 2600 ZeroLemon 7500 mAh
SGS4 Thickness With Door 7.94 mm 17.0 mm
Battery Mass 43.5 grams 132.3 grams

I ran our normal smartphone battery life test suite on the SGS4 GPe with the big battery installed. This is the same test we’ve run for a while now with the display set to 200 nits exactly and loading through a number of pages on a schedule, over both WiFi and cellular (in this case for consistency with the previous GPe test, still T-Mobile LTE). Obviously the results speak for themselves here, runtime with the big 2.8x size battery is huge.

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

On the cellular test, we see a 2.7x scaling, very close to the expected 2.8x scaling given the increase in battery. On the WiFi test, we see just over 3x scaling, even better. I previously had no issues getting through a day with the stock SGS4 battery, I’d expect with the nearly 3x scaling you could possibly get 3 days of use out of this combo.

Device Charge Time - 0 to 100 Percent

The other tradeoff is of course an increase in charge time. Samsung is in a better position here thanks to the availability of 2 Amp (10 watt) charging using their supplied charger which includes proprietary 1.2V signaling on D+/D- pins. Unsurprisingly charge time goes up as well with the ZeroLemon, and even with that Samsung 2 Amp charger, it takes 7.5 hours to charge the ZeroLemon battery from completely empty. With this much charge time, it’s clear to me that without increased charging current this is effectively the maximum practical battery size for the SGS4, given the expectation that you can plug your phone in dead when you go to sleep and wake up with it fully charged (and sleep 8 hours a night). If you use the wrong charger (USB BC 1.2 compliant), a full charge could take just over 12 hours given this same scaling.

If you’re willing to make the size and weight tradeoff and want an absolutely huge extended battery for the SGS4, the ZeroLemon 7500 mAh battery seems like a pretty good choice.

Source: ZeroLemon (Amazon)

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  • uhuznaa - Tuesday, July 23, 2013 - link

    This thing would be much more interesting (and sellable) if they had put some thought into the fucking shape of the battery/back. Just sloping the thing smoothly towards the edges would make a huge difference. Offering some nice colors and textures would also help.

    This way it's just a brick for those who don't mind carrying a brick.

    If I would have to design a modern smartphone I would put the camera into the centre and which has a battery with a hole in the middle and a sloping shape down to a somewhat thin edge. This way you would get a smartphone that feels good in the hand, that still has some serious volume to carry a big battery and some serious depth where it is necessary to integrate a camera with a huge sensor or an optical zoom.

    But this thing is certainly no better than a tablet. Face it, it's just a brick. If you can carry this, you can carry also something that is much larger.
  • Death666Angel - Tuesday, July 23, 2013 - link

    It's hard to understand what you are saying.

    Getting a battery with a hole in the middle will be pretty expansive, as it is not something you can just source from any number of supplies.
    It is not pretty, I give you that. But I doubt the people who are considering this thing are too concerned about looks. For them, it is like a necessary addition that can replace carrying one or two spare batteries/battery packs and still do all they need with the phone.
    And I have not idea why you bring up tablets. There is still a big difference between a smartphone like this which will last you 15 to 20 hours and a tablet that is a very different form factor and last you between 5 and 10 hours... maybe not even with phone service.
  • frypan - Wednesday, July 24, 2013 - link

    this battery is not meant for you. useful for people who are miles away from a charger and swapping battery crazy. I used to swap battery in and out but did so much that it wastes a good amount of my time. i'll be carrying just as much batter on myself anyways, may as well just get a battery that delivers.
  • jimweda - Saturday, August 31, 2013 - link

    I agree with you frypan and I think Samsung and other manufacturers should stop trying to make things so thin at the sacrifice of battery life. We should be able to go a full day without having to recharge but even casual users that I know complain their battery life.
  • jimweda - Saturday, August 31, 2013 - link

    You're kidding right? hehe
  • Aenean144 - Tuesday, July 23, 2013 - link

    "ZeroLemon" Interesting name.

    7.5 hr charge time? I think I average around 6 hrs sleep. :( Anyways, any word on heat? During usage? During charging?

    Also, does deeper camera hole interfere with back cam performance?
  • flyingpants1 - Tuesday, July 23, 2013 - link

    Good questions. Brian, please test RF performance, heat, and GPS..

    According to Amazon reviews, the camera hole does not affect the camera much.
  • Calista - Thursday, July 25, 2013 - link

    I guess you also spend an hour getting dressed and having breakfast as well as an hour or two in front of your computer/TV before getting to bed, i.e. plenty of time to letting it charge fully.
  • jimweda - Saturday, August 31, 2013 - link

    Every one I've talked to so far says camera works fine and no sign of heat issues which is why I went and purchased one. Just waiting for it to come in.
  • 01nb - Tuesday, July 23, 2013 - link

    My brother rocks the equivalent from ZeroLemon for his S3. I have gone the other route - I bought a package of 2 additional batteries + wall charger from Anker off Amazon. I just don't want something that bulky to carry, so I'd rather just carry an extra battery around - the stock battery is so thin that I forget that I even have it in my pocket most of the time.

    One of the selling points of the S4 was the form factor. These massive batteries are a major compromise and the tradeoffs are too great for me.

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