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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  • Impulses - Wednesday, July 24, 2013 - link

    You lose something like 30% of the stated capacity of the external battery, at least in my experience with a 5,600 mAh Anker... Personally I've grown to prefer the external/USB battery approach, since it's not something I need on a daily basis. If it were, I'd probably opt for carrying a second stock battery, less overall bulk and if have an erratic schedule you can keep a third one at home or in the car and just cycle them to make charging less of an extended process... I'm glad Samsung has stuck to removable batteries tho (despite never having owned a Samsung phone), having more choices is always a plus (and one of Android's advantages).
  • frypan - Wednesday, July 24, 2013 - link

    this battery is for ppl who truly use their phone aggressively. That they have more phone usage time than computer usage time.

    Like a door to door salesman.

    Also if you are a bittorrent freak with unlimited 4G dataplan uncapped like myself, this is your next best friend. A slim battery only gets you 2 hours up time maximum and everytime you swap out the battery, the app restarts and rechecks all the files. not so fun to wait for that and waste more power doing so.
  • yannigr - Wednesday, July 24, 2013 - link

    I would prefer something like this
    but not from energizer. There are many options like this from various name or noname manufacturers at 1/3 or lower of that price.
  • SunLord - Wednesday, July 24, 2013 - link

    I wouldn't use this day to day but if I'm going out where I don't have ready access to power this would be a nice option. I could use this for weekend up north for say camping or hunting and not have to worry about recharging
  • Brainslime - Wednesday, July 24, 2013 - link

    I have the s4 and the Zerolemon battery.. I think theres a problem with battery report with the s4.

    I charge my battery to 100% and get a green light. When my battery reached about 18% for other reasons I had to remove my sd card. I replaced my battery in the phone... The whole thing took about 30 seconds.. When I booted my phone. I noticed my battery charge was at 47% continued to use my phone (moderate to high use) managed 38 hr of use.. there has to be a glitch in the software thats initially giving low battery life levels.
  • Brainslime - Wednesday, July 24, 2013 - link

    I charged my phone to 100% ang got a green light. At 18% I had to remove the battery and pop it back in for some unrelated reason and when i booted my phone. It was at 48%. Managed to get 38 hrs of use on my s4 with the Zerolemon battery. I think theres a problem with the way the s4 is reporting battery charge.
  • piroroadkill - Thursday, July 25, 2013 - link

    Please include it in the tests! I have one, and bought it specifically because it is a very decent thickness and weight, yet it has the largest battery of any stock smartphone.
  • JlHADJOE - Thursday, July 25, 2013 - link

    I actually like the way this looks with the provided case. It'll go very nicely with a black S4, I think.
  • pliablemoosethebanned - Thursday, July 25, 2013 - link

    I tried a ZL battery with an S3, couldn't stand it, cheap back, and way too big. I have a 2nd battery for my Note 2, rarely need it
  • EJ257 - Friday, July 26, 2013 - link

    Buy 2 batteries and a charging cradle. Then you just swap battery when one runs out. With over 10 hours run time it should give the other one plenty of time to charge up :D

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