SafPWR Battery Case for iPhone 4: Almost Invisible

The SafPWR Fusion Lithium Polymer battery plus case for the iPhone 4 is incredibly slim, hardly adds any size, but doubles the battery life. The Fusion can deliver power immediately when the iPhone is inserted, or it can remain in stand by mode. This reviewer was impressed.

The battery in the iPhone 4 has a capacity of 1,420 milliamp -hours (mAh). The Lithium Polymer battery in the Fusion has a capacity of 1,500 mAh, so it more than doubles the iPhone’s native capacity without adding a lot of bulk.

The case itself is a bit slimmer and feels lighter than the similar case I reviewed for the iPhone 3GS in November, 2009. With a total length of 4.96-in and a weight of 2.4 oz, it adds little to the the iPhone 4’s 4.5 inch length and 4.8 oz. weight. The fit and finish is better than before, and the case isn’t subject to the curing issue that caused the paint to peel on that older model’s earliest units. It’s grey plastic around the edges and thin leather in the back.


The packaging is good, and quite cleverly, the customary cardboard insert for the case that tells this customer this is an iPhone product has the small manual tucked inside.

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The distortions are small bubble in the plastic.  Not a problem.

It would expect this kind of sturdy, quality packaging for an eighty dollar product that comes all the way from China.

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Inner packaging is robust.

Included is a roughly 30-inch (75 cm.) microUSB cable that’s plenty long to extend from your Mac or USB hub to a safe place for the iPhone.

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Unpacked case and microUSB cable.


To insert the iPhone, pull off the small, u-shaped plastic retainer, slide the iPhone in until it mates with the 30-pin jack, and replace the u-shaped retainer. (However, note that the instructions advise you to fully charge the battery before plugging in the iPhone. According to the manual, the first charge should be no less than 8 hours. Thereafter, regular charging should take about 3 to 4 hours.) The retainer stays on without fear of falling off, yet is easy to remove with a gentle tug. I fear that this is the one weak point: it’s a part that could easily get lost or broken.

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  • Stand by mode when iPhone inserted and plug disconnected: Draw power from Fusion or cut off power to iPhone.
  • 1,500 mAh lithium polymer SaFPWR smart battery, rechargeable for over 500 cycles.
  • Intelligent energy management technology (EMT) increases iPhone run time by more than 100%.
  • Allows iPhone to charge and sync while in the SaFPWR smart battery case.
  • Built-in short-circuit, overcharge, over discharge, energy flow back, and malfunction protection.
  • Case is built to exact specifications to provide secure fit and proper function of iPhone 4.
  • High-quality leather offers distinctive, yet durable, looks.
  • Openings for iPhone charge port, microphone, speaker, camera, and proximity sensor.

One of the features is a set of holes at the botton of the case to allow one to hear the iPhone speakers. As the company representative explains it, “Our team looked at venting the sound out the front of the device but felt that possibility of distortion was greater that the benefit of doing so.”

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iPhone 4 inside Fusion.


  • Doubles iPhone capacity without much additional bulk.
  • Protects all but face of iPhone
  • Connects, charges, sync via USB while in case
  • Stand by mode.
  • Non skid, soft leather back.
  • Anti-glare black region around camera port.
  • Easy assembly and disassembly.
  • All ports accessible — except for microSIM.


  • No longer fits in a snug belt holster.
  • Non-skid back picks up and holds cat hair, lint. (But easily restored to pristine condition with Scotch Tape.)
  • A small plastic retainer that clamps on is easy to lose.
  • Is specific to iPhone 4 — until we know more about the iPhone 5.
  • May not work with all headphone jacks. (See below.)

Likes and Dislikes

I liked the stand by mode, only available when the power cable is unplugged. You can elect to have the Fusion immediately supply power to the iPhone or you can remain in stand by mode — in which power is cut off to the iPhone. You toggle this mode by pressing and holding the button next to the charge status LEDs on the back. (These work just like the ones we know from MacBooks.) The visual confirmation comes from seeing (or not seeing) the green battery icon or the lightning bolt icon on the top right of the display.

What I didn’t like was the manual. The white on black is heard to read. The print is too small. It was translated into English by a person who’s not native to English, and that creates all kinds of technical ambiguities. For example, it fails to explain stand by mode very well at all. I am told that the manual will be re-written, and I was shown a draft of the new U.S. written version. It is enormously better. I hope it makes it into production soon.

I should note, as an aside, that I have a 3.5 mm audio jack extension cable for my Urbanears Tanto headphones. The Tanto’s jack is fine, as is the jack on my older Sony headphones. But the extension cord has what I fear is a non-standard gold ring around the base that’s too large to fit through the hole in the Fusion. There’s no fault with the iPhone, the Fusion case, the Urbanears or the Sony headphones. It lies only with the extension cable, but I wonder if some other headphones might have the same problem. It might be wise to verify your own headphone cable. Here’s a photo that might help.

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Close-up of my cables. (See text above for explanation.)

Do I Recommend it?

I have never been completely happy with other iPhone cases that double as backup batteries. There’s always something I don’t like. This case. however, pleases me, and so I do recommend it. I expect that I’ll never be without it when I’m on travel.

For those who need protection for the face of the iPhone, there’s a sister product, the Milano. It’s available in several colors and textures, has a higher capacity battery, and costs slightly more.

Product: Fusion for iPhone 4

Company: SafPWR (China)

List Price: US$79.95



Minimal addition of size and weight. Helpful stand by mode. More than doubles iPhone 4 battery life. Good fit and finish.  Non-skid backing. Can sync to Mac/PC while in case.


Original manual very poor. (But being rewritten.)