How to double your phone's battery life

These smartphone cases pack a backup supply of juice, ready to recharge your device when you need it. Here's how they compare in price and performance.

By MSN Money Partner Mar 12, 2014 11:48AM

Mophie Space Pack cases (c) Mophie.comBy Joanna Stern, The Wall Street Journal

Battery-life panic disorder. You won't find it in any medical textbook, but I assure you, when a smartphone's battery indicator turns red, the corresponding feeling of complete powerlessness is real.

The Wall Street Journal on MSN MoneyI used to suffer quite badly from it, sitting on dirty floors as my phone charged at whatever power plug that happened to be available. But I've since found relief: iPhone and Android phone cases that can double your battery life.

Often called a "Mophie," because of one of the first companies to release them, the case connects to your phone via the power port. When the battery is low, you turn it on and before you know it, you're back in the green. It'll usually double the thickness of your phone, but if these cases were a prescription drug, that would be considered a minor side effect.

Mophie is no longer alone. In fact, the competition is outrunning it, and that's good news. I tested 11 cases and discovered you can put more power in your pocket while spending less with cases made by others.

Mophie's new iPhone model, called the Space Pack, does something no other case can, though. The $150 cover not only has a battery baked in but also 32 gigabytes of extra storage. You have to use Mophie's app to shift photos and other files to the outboard drive, but it's helpful, especially for unloading photos. As a result, the Space Pack's battery is smaller than the ones in any other case I tested.

The other standout iPhone cases included the Mophie Juice Pack, the powerhouse Lenmar Meridian and the stylish Boostcase. I also threw in a bargain-basement case, which can be spotted in multiple listings on (AMZN), sometimes under the brand PowerBot or Power Bank. It cost me $15.

And although my core tests were done using identical new AT&T (T) iPhone 5S models, I also tested some cases for the most popular Android phone, the Samsung (SSNLF) Galaxy S4.

The two Mophies did the poorest in my tests -- neither could fully charge a dead iPhone and that's the baseline expectation of a battery pack. The $90 Lenmar passed that test. Though it's about the same size as the $120 Mophie Juice Pack, it has a bigger battery. It charged the iPhone to 100 percent and had a little juice to spare, though not much.

The Mophie cases were the fastest to charge, however. The company says the faster output can make the cases slightly less efficient and recommends users constantly charge the phone throughout the day, rather than all at once when it's dead or nearly dead.

The $100 Boostcase seems to be the only stylish option for saddling up a phone with a big battery. Available in a palette of fashionable colors, including "mint" and "wine red," when you are done charging, you can swap out the battery attachment for a little wallet. It got a dead phone up to nearly -- but not quite -- a full charge in under two hours.

The real Cinderella story came with the generic case from Amazon. Not only is it thinner than many pricier competitors, but it charged a dead phone up to 100 percent. The only downside was that charging took twice as long.

There is some concern over no-name battery cases such as this one, however. It is unclear who makes the generic case, as it is sold by many vendors in prices ranging from $9 to over $50. And I couldn't confirm if it has gone through proper third-party testing.

The cases from Lenmar and Mophie are certified by the Underwriters Laboratory, a safety certification organization, and have reliable one-year warranties.

John Drengenberg, consumer safety director for UL, cautions there are fire and explosion hazards with the lithium batteries in mobile products. That's why it's important to confirm that products like this come from a reputable manufacturer and are independently tested, Mr. Drengenberg says.

With that warning, I can also tell you I know two people who have used these generic battery cases for months with no problems.

On the Android side, Mophie also lagged behind. The $90 Incipio offGRID was able to push the Galaxy S4 past the 85 percent mark, as opposed to the Mophie's 68 percent. The bulky $60 Lenmar Halo S4 has the biggest battery. But rather than charge the original battery, it extends the phone's overall battery life. In my tests, battery life was doubled.

The surprise finding is that price has very little to do with performance. When it comes to value, performance and safety, Lenmar is my top choice for the Apple (AAPL) iPhone and the Galaxy S4.

With a chunky case and the right attitude, we can fight battery life panic disorder -- or at least fend it off until smartphone makers figure out a real cure.

More from The Wall Street Journal

Mar 12, 2014 12:22PM
If you are spending that much time on an electronic device that you need to spend that kind of money you are a MORON!
Mar 12, 2014 12:18PM
If we could invent a battery that screens "whatudoin" calls from calls of substance, we would have no need for extra battery life.
Mar 12, 2014 2:52PM
Maybe these same people who are so worried about their cell phone battery dying carry an extra 20 gallon tank of gasoline in their cars??  There are more important things in life than a cell phone battery.  If you are spending that much time a day on one & eating up the battery you have a little too much time on your hands!  Use it for a business call, a quick conversation or an emergency....not to take a picture of a fat person walking around Wal-Mart & texting it to everyone or posting it on Facebook for all the other idiots to reply to!
Mar 12, 2014 1:24PM
This just blows me away, you idiotic people should try putting your phones away and enjoy life! nothing and no one is that Da*n important. some of these posters speak of two phones! really! stupid is as stupid does, controlled by a little device.
Mar 12, 2014 12:34PM
On the S4, press and hold home button and close all apps! Turn all that crap off and enjoy a day and a half of battery power! If you have sketchy phone signals in your area, your phone will search for a signal and it will drain ANY battery fast!
Now who is smarter, you or the phone. I have no need to go on the web from my phone.
Mar 12, 2014 12:09PM
I am shocked that anybody would pay $150.00 for a phone cover. I have had the same phone for six years and only have to charge 30 minutes twice a week.
Mar 12, 2014 2:07PM
mainly people age group 10-35 use phones...enormous amounts of teens and young adults...dont they have a life? you walk down the street they are on one, in the waiting room, at school, at work, in the store, at the dinner table, and anywhere at a life? you're only " friends " are FB friends who talk to you once a month on facebook and everything you do requires socializing on a real life you dont talk to anyone, you walk around and hide behind it so you dont have to look at anyone or wont be appraoched by anyone " security blanket " i call it
Mar 12, 2014 1:05PM
Dont want it yet, its antisocial...I have to be deprogrammed...
Mar 12, 2014 2:39PM
Well here is a report on nothing another slow news day I reckn.
Mar 12, 2014 4:03PM

Sad, isn't it that folks believe they are important enough to have instant access to it all with a phone or actually a mini computer that takes calls.

Remember 25 yrs back, we had flip phones that stayed charged for several days not just hours and sometimes we even left home without one on us???

Still have my flip phone and still have several days charging,,,hahahaha

As for the texting and messaging,,, why, if it takes more than a couple of keys strokes that you have in the phones memory for a persons number, usually 4 max, then it is a waste of time to begin with.

Don't need the garbage in and out on my phone. You want to talk to me CALL ME. or leave a message.

Mar 12, 2014 12:59PM
I have the droid maxx and I can go a couple of days with heavy use no problem. Screw making it thicker and bulkier.
Mar 12, 2014 12:17PM
Double the thickness of my phone? NO THANKS! I usually carry a fully charged backup battery with me if I'm gone all day. 
Apr 2, 2014 2:20PM
One day we will have phones in every room of our house and won't have to worry about cell phones. They will also be on each street corner and cost 35cents and we won't have to worry about big phone bills.  It will be revolutionary.
Mar 12, 2014 5:13PM
this is why I like my dumb phone :D

in a good reception area it has a good week of battery life! 
Mar 12, 2014 5:19PM
What ever happened to that HS girl's invention? It charged phone batteries in 15 seconds???
Mar 12, 2014 5:13PM

A company called  "Battery On The Go"   sells the only portable battery that uses 100% organic polymers?  its eco friendly, this crazy little battery charged my iPhone 5 over 11 times on one charge... As I sat there in amazement I recharged and got 13 full charges on my iPhone 5.. Those guys must have some magic inside that thing!!  it never got warm and charged my phone in half the time my wall chargers takes..  I love my power bar 12,000mAh -- Great job battery on the go guys!!!  

Mar 12, 2014 1:09PM
I have been using a PowerBank and a PowerCase on my two iPhones (iPhone 5 and iPhone 5C) for quite some time (almost 1 year on iPhone 5 and about 3 months on iPhone 5C) with no problems.  I only paid $16 each for them on Amazon.  I am able to charge the phone and the case at the same time overnight.  Both cases are able to give me double the battery life that the standard phone battery offers.
Mar 12, 2014 2:07PM
Did you know that the heat from a phone battery can cause an image on your body when you go thru TSA screening at the airport?
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