Most people charge their mobile phone using the power cord that came with it. Yet we’ve all encountered situations where there’s no socket within reach. Power packs are the solution.
Yet the external batteries in power packs don’t always achieve everything they promise.
Power packs are generally the same size as a mobile phone and cost between $20 and $40. Countless models are available on the market; several can even produce their own electricity using solar cells. Kai-Christian Moeller from the Fraunhofer Institute for Silicate Research in Wurzburg, Germany, sees them as little more than bells and whistles. “Solar cells of that size aren’t big enough to charge a mobile phone,” he says.
Solar power packs — and all other battery packs of this type — are filled with rechargeable batteries. Even under ideal conditions, it could take eight hours or longer, Moeller says. Owners of a solar cell power pack would ultimately end up relying primarily on the same wall socket as everyone else. Moeller has been researching single-use and rechargeable batteries for years. He isn’t particularly impressed by power packs without solar cells either: “To be completely honest: I’d rather just bring along a second battery.”
But that’s not always possible, says Daniel Schaechter, editor at the online tech magazine CNET. “The decisive benefit of a power pack is that I don’t have to turn my mobile phone off to charge it,” Schaechter says. Furthermore, there are some devices, most notably Apple’s iPhone, whose battery cannot be removed without tools.
Cracking the case open to get at the battery typically voids the warrantee.
Power packs could be of potential interest for business travellers, Schaechter explains. “On some days I know in advance that I’ll be doing a lot of calling or e-mailing, such as at trade fairs,” he says.
In those cases a power pack is the more practical option. “I usually have to have the second battery in the phone to charge it. So that means I’ll have to be switching batteries ahead of the trip, during the trip, and afterwards,” he says. A power pack eliminates some of that complexity.
External energy sources can also be helpful for vacationers with a second mobile phone, MP3 player, or digital camera in their luggage.
The key thing, of course, is that both the devices and the power pack share the same connection interfaces. Almost all power packs offer power via USB ports. Mobile playing consoles and older mobile phones sometimes feature more exotic plugs, though. Consumers should check carefully before buying any power pack to ensure that it has the right cables and adapters for their own situation.
The second key point when selecting a power pack is capacity. “The question is always: How much energy am I getting for my money?” says Bernd Adam, editor at Guter Rat, a consumer reviews magazine in Germany. He tested numerous power packs and found that the nominal capacities often significantly overstate the reality. “Those are likely the theoretical maximum values,” he says. “A little power is always lost during the various charging processes.” The claims are nevertheless suitable for rough comparisons.
If you want to know how much electricity a power pack will deliver to a given phone, the best idea is to compare the capacity with the hard data provided on the phone battery. Capacity and charge are generally indicated in milliamps (mA) or milliamp hours (mAh).
Traditional mobile phone batteries typically have a charge capacity of 1000 milliamps. That figure is a bit higher for smartphones.
Once a vacation or business trip is finished, power packs are typically tucked back away into a drawer or closet, but it’s a good idea to discharge the devices first, says Moeller. “Lithium ion batteries should fundamentally not be charged for extended periods of time. It’s comparable to a rubber band left permanently stretched,” he says.
While it’s not dangerous, storing a fully charged battery reduces its lifespan. A well-built battery should be able to hold up to 500 charge and discharge cycles without losing more than 20 per cent of its capacity.
