Portable backup batteries have become an important accessory to keep many of our gadgets charged. It’s a category that’s exploded in recent years, fueled in part by devices such as the iPhone with non-removable batteries. When you're not able to snap in a second battery or access an outlet to recharge, a backup battery offers the best solution. It’s typically a small, thin box containing a lithium ion battery and circuitry with a battery gauge, an on-off switch and connectors for charging it and charging your devices using separate USB cables.
They’re incredibly useful in a pinch. I carry one to charge my iPhone and Bluetooth headset when I’m on the road and doing lots of calling. It’s a big help when using the GPS function on your smartphone, which can drain a battery in less than three hours. The battery also recharges my phone on a long airline trip when I’m listening to music or watching videos. Some are even powerful enough to charge an iPad.
The batteries are rated by their capacity, in milliamp hours (mAh). Phones typically have batteries with a capacity of 1200 to about 2000 mAh and tablets of about 6000 mAh. So if you buy a backup battery for an iPhone 5 that has a 1434 mAh battery built in, then to completely recharge the phone from empty requires a battery of about 1700 mAh. It needs this extra capacity because there is about a 20 percent loss when charging from an external battery.
The maximum output current of the battery is also important, because some batteries can only output a maximum of 0.5 amp (the same as many computers’ USB ports). Others can output up to 2 amps. This affects the ability to charge iPads and iPhones in a reasonable period of time.
I’ve been testing two major brands of accessory batteries, the Mophie Juice Pack Powerstation Mini ($60) with 2500 mAh capacity and the recently introduced ZaggSparq 3100 ($70) with 3100 mAh.
The Mophie is an attractive matte black rectangular slab that’s styled to look a little like an iPhone, with a silver band running around the edge. While it may be good-looking, it has some serious deficiencies. It’s unable to be recharged while it’s charging your device, a huge inconvenience. Its on-off switch can be inadvertently turned on, and it requires a separate USB charger and micro USB cable to charge it.
The ZaggSparq 3100 is a slightly larger device and not quite as stylish, but offers many improvements over the Mophie. It can be charged while it is charging, it needs no extra charger or cable, and it plugs directly into an outlet using its built-in folding plug. It can also output sufficient current to charge an iPad. Bottom line: The ZaggSparq 3100 is a far superior product.
Plantronics Voyager Legend headset
The Legend is Plantronics' latest version in its long-running Voyager Bluetooth headset line, an iconic design that’s become the gold standard of wireless cellphone headsets. The Legend retains the over-the-ear design with a boom microphone. I’ve liked this design because it stays on your ear, has extended talk time with its larger battery, and the boom improves call quality.
The major differences between this model and its predecessor, the Voyager HD, is a new multi-microphone design that’s intended to provide better noise rejection, a longer seven-hour talk time, a new magnetic connector for attaching to the charger, moisture proofing, and a new line of accessories. Like the previous model, it knows when the headset is placed on your ear and automatically answers a ringing phone or transfers one in progress from the handset to the headset. Or you can say "answer" when it’s being worn, and it will answer the ringing phone after announcing the caller.
Performance is excellent using an Android phone, but I did experience poor-sounding digitized calls and garbled sound on occasion with an iPhone 5. It’s a problem that exists with other brands of Bluetooth headsets, and apparently is caused by a design flaw in the iPhone 5. Apple engineers are working on a fix, and Plantronics has come out with upgraded software. This is perhaps a consequence of Apple’s ultra-high secrecy that prevents its phones from being tested more widely before being released.
The Legend has a sleeker look and a new magnetic connector that replaces the micro USB connector used on earlier models. That enables quicker attachment to the charger and accessory desktop stand, but also requires a custom cable for traveling, a step backward. A good workaround is to use its optional charging case ($30), which provides an additional 14 hours of talk time when the headset is stored, and can be charged using a micro USB charger. (plantronics.com, $100)
Baker is the author of "From Concept to Consumer" published by Financial Times Press and available at Barnes & Noble, Amazon and other booksellers. He has developed and marketed consumer and computer products for Polaroid, Apple, Seiko and others; holds 30 patents; and is an Ernst & Young Entrepreneur of the Year. Baker can be heard on KOGO AM the first Sunday of each month. Send comments to email@example.com. Comments may be published as Letters to the Editor. Baker's blog is blog.philipgbaker.com, and his website is philipgbaker.com.