Samsung Galaxy S4 ZeroLemon 7500 mAh Extended Battery Review

One of the chief differentiators with the Samsung Galaxy S4 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.