You undoubtedly know people so smitten with their smartphones and tablets that they experience separation anxiety when asked to put them away, even if it's just long enough to get through dinner. But that is nothing compared with the angst they feel when their devices' batteries are getting low. Think tremors and rending of garments.
If you happen to be one of those people, you might consider joining a 12-step program — or maybe just buying a backup battery for recharging on the go. The market for these mobile power sources has grown exponentially in the last two years, with more compact and more powerful options available that allow you to recharge hundreds of times. Which one is best depends on how much power you want on hand and how much weight you are willing to carry.
"Mobile chargers are becoming one of our most popular categories," said Victor Setton, the chief executive of Mobile City in TriBeCa, who bought one himself after he missed critical moments of extended play at the US Open because he left the match to recharge his phone. "Everybody has had moments like that when you are watching your phone power down and it's killing you."
First, you need to determine how much standby power you need. Battery capacity is measured in milliampere hours (mAh). The more milliampere hours a battery has, the longer it will run, somewhat like gallons of gas in a car. Most smartphone batteries have a capacity of 1,500 to 2,100 mAh, while tablet batteries are in the 6,000 to 11,000 mAh range. To fully recharge these devices, you need an auxiliary source that meets or exceeds that capacity.
If all you want is a quick charge to give you a couple of hours until you can get to a wall socket, go with something small, inexpensive and lightweight like the 1,800 mAh Triple C Power Mate Plus ($29), which plugs directly into an iPhone 3GS, 4 or 4S; the company, Triple C Designs, is working on one that will be compatible with an iPhone 5. The Power Mate Plus is about the size of a woman's compact, weighs 1.2 ounces and comes in a variety of decorative designs.
The 2,200 mAh MiPow Power Tube ($39) is compatible with a wider range of mobile devices and will completely charge a smartphone. Encased in what looks like brushed aluminium, it weighs 2.5 ounces and is the size of a cigarette lighter. There are incrementally larger-capacity Power Tubes up to the 5,500 mAh version ($99), which weighs 4.8 ounces and can charge a smartphone a couple of times or charge a tablet 50 percent.
A larger footprint and more heft will provide even more charging capacity. Take the HyperJuice Mini ($100), which is about as big as a smartphone but thicker, weighs 8.4 ounces and delivers 7,200 mAh. It also has the advantage of multiple charging ports so that two mobile devices can be charged at once as long as they are USB compatible.
HyperJuice offers battery chargers with progressively larger capacities up to 61,000 mAh ($450). That charger is about the size of a thick paperback book and weighs 4.7 pounds. It is compatible only with Apple products but has enough oomph to keep a MacBook going 32 hours, extend iPad battery life an additional 89 hours or fully recharge an iPhone up to 52 times.
For those who prefer not to juggle one more device, there are charging sleeves or jackets that snap onto the devices they already have. Mophie is the leading provider of iPhone charging cases with its popular Juice Pack Air ($80). It has a 1,500 mAh capacity and adds 2.5 ounces to the weight of an iPhone 4 or 4S. An iPhone 5 version is expected early this year.
For Android users, there is PowerSkin, with 1,500 mAh charging cases for a variety of smartphones. They range in price from $40 to $80, with some selling for as little as $5 with shipping if the model has been discontinued.
If you want an iPad charging case, there is the KudoCase ($130), which relies partly on solar power. It converts outdoor and indoor light into energy for a continual trickle charge. Just know that six hours of sunli