An emergency phone charger is a device that can provide on demand power to a cellphone if the battery has gone dead unexpectedly. The three main types of emergency phone charger are traditionally charged battery packs, hand cranked devices, and photovoltaic (PV) solar units. Chargers in each of these categories can be useful in different circumstances, and may come in handy for various emergency situations. Some people carry around a spare, charged battery for their cellphone, though a battery pack charger differs from this solution in that it can typically be used to provide power to more than one type of device. One benefit offered by both hand crank and PV chargers is that they do not have to be charged themselves.
Battery pack based chargers may be either universal or phone specific, and can be rechargeable or disposable. A universal emergency phone charger will typically have a number of different charge tips, while a phone specific unit will have an integrated plug that works only with certain phone models. Disposable units can usually be stored long term in a glove compartment or a backpack for emergency use, while rechargeable units can be kept charged and then used again if they are ever needed. In either case, these battery pack chargers typically must be monitored regularly to ensure the charge does not run down.
The main benefit of either a hand crank or PV emergency phone charger is that there is no charge to run out, so they can typically be stored indefinitely in case of emergency. Hand crank units may also be integrated with other functions like a flashlight or radio, adding to their usefulness in an emergency situation. These units are typically universal, with charge tips that can be acquired to match a particular phone or other device. A hand cranked emergency phone charger may be simply plugged into a phone using the correct tip, then cranked to charge the battery. Repetitious cranking may be required to sufficiently charge a phone battery with one of these units, so a PV charger may also be useful in case of injury.
Like hand cranked units, PV chargers generate power rather than storing it. In the case of a PV charger, direct current (DC) electricity is typically generated by a small solar panel. Radiation from the sun can be converted into electricity via the photovoltaic process, allowing one of these devices to function as an emergency phone charger in the presence of sunlight. The main drawback associated with PV chargers is they will not function at night, and may operate poorly in overcast conditions.