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Computerized Investing > April 27, 2013
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by Wayne A. Thorp, CFA


Battery case for Samsung Galaxy S III smartphone.

Smartphones today are an investment. Even with subsidies from phone companies, an advanced smartphone will still run you hundreds of dollars. Furthermore, today’s smartphones are battery hogs. As a result, more and more companies are combining two necessities: phone case and external battery. In this column, I have reviewed several battery cases over the years. Most have been for the iPhone, as that is what I use. However, as Samsung has narrowed the gap with Apple, we have had readers calling for accessories for other phones. This week I take a look at a battery case from a company I am very familiar with: mophie. I previously had a mophie juice pack plus for my old iPhone 4S and am anxiously awaiting the iPhone 5 model. In this review, I will be looking at a mophie case for the Samsung Galaxy S III, which was given to me by the company.

Out of the Box

The box contains the juice pack, micro-USB cable and user’s manual. The case itself is made out of impact-resistant plastic and is actually a two-piece slider, similar to that of the juice pack plus I reviewed last year for the iPhone 4/4S. You pull the two pieces apart by squeezing the top part of the case until the top part pops off. Then you slide your S III down through the larger piece until it’s plugged into the micro-USB plug at the bottom. You reconnect the top piece and you are ready to go. The pieces are held together well enough that it is a bit of a struggle to get them separated. I definitely didn’t feel like the two pieces would come apart accidentally. The case offers wraparound protection, but does not cover the screen. The raised bezel of the case, however, keeps the phone’s screen off a flat surface when the screen is set down. There are also rubber pads inside the case that serve as shock absorbers. I must admit that this case did not feel as sturdy as the juice pack plus for iPhone 4/4S.

Anyone looking to preserve the lines of their phone won’t be using a case, let alone a battery case such as this one. The case measures 5.91 inches by 2.97 inches by 0.67 inches. The dimensions of the Galaxy S III by itself are 5.38 inches by 2.78 inches by 0.34 inches, so the case adds an additional half-inch to the length and nearly doubles the thickness. In addition, the case itself weighs 3.5 ounces, bringing the total weight of case and phone to over half a pound. While I am not one who pays too much attention to aesthetics, this case doesn’t look nearly as nice on the phone as some of the cases I’ve reviewed for the iPhone. But, security and battery life are its primary function, not style.

On the bottom of the case is a micro-USB charging port. This is where you plug in the case to a USB charger to charge the case’s battery (if your phone is fully discharged when you plug in the case, the phone will charge first). You can also use this USB port to transfer data on and off your Galaxy S III without having to remove it from the case.

There are cutouts on the back for the camera and speaker, and integrated buttons on the sides for controlling volume and powering the phone on and off.

On the back of the case is an On/Off switch. This is one feature I wish more battery case makers would implement. The switch allows you to put the juice pack in standby mode and preserve the case’s battery until you need it. When in standby mode, you can still charge the juice pack’s battery or sync the phone via the micro-USB port. Next to the On/Off switch are four LED lights that let you track the juice pack’s battery power status. Pressing the status button opposite the power switch will tell you how much battery life is left.

Out of the box, the juice pack was fully charged, but once you start using it, it takes about two or three hours to fully recharge it.


The bread and butter of the mophie juice pack for the Galaxy S III is the 2300 mAh lithium rechargeable battery built into the case. According to mophie, the juice pack will roughly double the battery life of the Galaxy S III. This translates into an additional 32 hours of audio, eight extra hours of video playback, 11 extra hours of Wi-Fi Web browsing or nine more hours on a 4G network. On a 4G network, the juice pack will also provide an extra seven hours of talk time or nine more hours on a 3G network.


As a battery case, the mophie juice pack for the Samsung Galaxy S III works as advertised, nearly doubling the amount of talk time you have. I am less convinced by how well it will protect your phone, however. The case secures snugly around the phone, but it doesn’t give me the same sense of security that previous mophie cases have given me.

There is a trade-off, as is always the case (no pun intended) with accessories such as these. I don’t mind the added girth and weight the case adds to the phone, but other users may take that into consideration.

As an iPhone user, I forget that there was a time when I had a phone whose battery I could swap out. With my iPhone 5, I don’t have the luxury of replacing the battery when it gets low. However, you can do that with the Galaxy S III, and replacement batteries on Amazon cost less than $20. At almost $100 (less from online retailers), this may be a more attractive option for some.


  • Roughly doubles the amount of talk time
  • Dedicated On/Off switch
  • Battery indicator lights


  • Doubles the thickness of the phone
  • Nearly doubles the weight of the phone
  • Expensive compared to replacement batteries

mophie juice pack for Samsung Galaxy S III

$99.95 (Currently $68.30 at

Wayne A. Thorp, CFA, is the author of "Gadget Corner." All reviews are based on firsthand experience of the product or service. No third-party compensation is received for opinions on products, services, websites or topics. However, sometimes the author is not required by the manufacturer or their PR firm to return the product under review. In such instances, it is our policy to convey this within the review. The views and opinions expressed in these reviews are strictly those of the author. Any product claim, statistic, quote or other representation about a product or service should be verified with the manufacturer or provider.

Wayne A. Thorp, CFA is a vice president and senior financial analyst at AAII and editor of Computerized Investing. Follow him on Twitter at @WayneTAAII.


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