Reliability, portability and cost should be the main considerations when choosing a wireless cell phone charger. If you are looking for a mat cell phone charger, where you merely place the phone on a surface to charge, portability will probably not be a concern. On the other hand, if you are looking for an emergency cell phone charger, it will need to be both reliable and portable.
The mat type of phone charger creates a wireless connection between the phone and the charger, but the device must still be plugged into a power supply in the home or car. Some use a design called inductive charging that can charge virtually any device configured for it. A newer phone that is capable of using this type of wireless cell phone charger will have that feature mentioned in its specifications.
Other wireless cell phone chargers use an adapter that attaches to the phone. You place the phone on the mat or grid and it connects to the charging power. Finding the right adapter is fairly straightforward if you own one of the more popular or advanced kind of cell phones.
Mat chargers can also be used to charge mp3 players and other hand held devices. While primarily sold for home or office use, mobile versions are being developed. Some car manufacturers have announced that as early as the 2012 model year they will be featuring charging pads as part of their vehicles.
Portable, battery powered, emergency cell phone chargers are available in addition to solar and hand crank models. This type of wireless phone charger is designed to be kept in your briefcase, purse, or glove box. Unlike charging mats, these are adaptable to different cell phone models. The battery powered wireless cell phone charger is available as a disposable or a reusable device.
Hand crank models that are designed specifically for cell phone use are environmentally friendly, but their effectiveness depends upon how much power your phone uses and your stamina. Due to their small size, the cranks lack the leverage to generate power easily. According to consumer tests, five minutes of work provided only two to five minutes of talking time and would not revive a completely dead battery.
Another green solution is the solar powered wireless cell phone charger. It may or may not have a battery included to store a charge, and its effectiveness will depend upon the design and the availability of sunlight. Usually this type of charger is larger than the other types, and that makes it less portable.
You may also want to consider a hand cranked radio or lantern with a built-in universal serial bus (USB) connection. These are not dedicated cell phone chargers, but can provide power to a cell phone using the same cable that connects your phone to your computer. They are marketed primarily in regions where storms or other natural events routinely disrupt power. Their larger size makes cranking easier and will provide more power for your phone.