Keeping an iPhone charged throughout the day is tough, especially if you live on the smartphone, have emails pushed to you, and (gasp!) use location-aware apps constantly. There are plenty of battery solutions, and several of them are cases too. The Spyder i4 is the first battery case that can charge and sync an iPhone simultaneously, without ever needing to remove it from the case.

The i4 is an impressive iPhone battery case for three reasons: large battery capacity, simple charging, and smart design. It has a 2000 mAh battery, 140% larger than the iPhone’s internal battery. From 1% charge, the i4 can fully recharge the iPhone 4S and then some, if you don’t use the phone at all, and within two hours (faster than a normal charge). When it use, I’ve measured an average recharge going from 1% to roughly 80%, which is pretty good. The only trouble is, as expected, the case gets very warm when it’s charging your iPhone, so you don’t really want to hold it when on.

Charging the iPhone works simply enough: put the iPhone in the case and hold the button on the back until it activates the battery. What’s far more impressive is how the i4 itself is charged, either via MicroUSB like most smartphones today, or in an included cradle dock (that also uses MicroUSB). This makes the i4 very convenient; just drop it in the cradle to charge both the phone and the case battery. No plugging in cables, no hassle. The case itself also has a MicroUSB port for travel, or if you just leave the dock, say, in the bedroom. That way the dock can stay where it is and you can still charge both your iPhone and case with any USB.

That’s half of the smart design. The other half is the thin body, which adds 12mm of thickness to the iPhone 4/4S (a total of 21mm), which is very thick for a smartphone, but also very reasonable for a battery case. The other half is how Spyder takes into account audio. A normal case either blocks the sound slightly or has a hole in the case the speakers aren’t blocked. In both cases the sound is muffled because it’s either partially blocked or has to go through a tube. The i4 has a curved tube for both the microphone and speaker so that sound travels in and out of the phone more naturally, which makes audio not only come out clear, but also in a more natural direction: forward. So watching video is actually better with the i4 on because users don’t have to cup a hand over the speaker to hear sound properly.

The only design flaw in the i4 is the snap-on top.  The plastic top connects by sliding into two grooves on the case, and only then snaps into place. Connecting it properly isn’t as easy as it should be, but if you’re the type to leave a case on, then it’s only a problem once.

A slight concern I do have with the i4 is the charging speed on the iPhone 4S. Apple obviously put a lot of thought into how fast the iPhone should charge and built its chargers to accommodate that speed, with appropriate voltages. The i4 charges faster, which means it pumps more power into the iPhone over less time. In testing the i4 over a month period I haven’t noticed any change in how long my iPhone 4S can retain a charge, but it is something to consider if you plan on keeping your iPhone 4/4S for more than the two-year contract period.

The Spyder i4 is an excellent charging case, one that even under the harshest conditions can recharge a completely dead iPhone 4S to 80%. Add onto the case a charging base, a charging port directly on the case, and intelligently designed speaker holes and the i4 proves to be an excellent iPhone companion.

Editor’s Rating:

Rating: ★★★★½


Bottom Line: An excellent iPhone battery case that offers both great battery life and perfect convenience.


  • Fully recharges an iPhone 4S in standby, or up to 80% if used while charging
  • Includes a charging dock so the case need not be removed
  • Speaker holes included in case design for proper sound integration
  • Case charges the iPhone and battery when connected, either via dock or direct with a MicroUSB


  • The top snap-on connector is difficult to fit on properly
  • When charging, the case get’s very warm
The Spyder i4 can be purchased from Amazon for $79.99

James Pikover

Spawned in the horrendous heat of a Los Angeles winter, James was born with an incessant need to press buttons. Whether it was the car radio, doorbells on Halloween or lights, James pushed, pressed and prodded every button. No elevator was left unscathed, no building intercom was left un-rung, and no person he’s known has been left un-annoyed.