An iPhone's voltage requirements are important to consider when charging the device. Knowing the requirements will help with making decisions about third-party or alternative chargers for the iPhone. Concerns might also arise when traveling abroad in countries whose voltages are different. Luckily Apple designed the iPhone with versatility in mind.
The iPhone Battery Voltage
The iPhone uses a lithium ion polymer battery. The battery has a capacity of 1400mAh and 3.7 volts. The iPhone 4 offers up to 14 hours of talk time on 2G networks and 10 hours of Internet usage over a Wi-Fi connection. Its predecessor, the 3Gs, offered 12 hours of talk time on 2G and nine hours of Internet usage over Wi-Fi. Because of the iPhone's many functions and applications, these figures can vary quite a bit.
The iPhone uses a charger with a USB adapter. USB offers approximately 5 volts, although there is some minor variation with usage. Any third-party or alternative charging method should also offer approximately 5 volts.
Using electronics internationally is more than a matter of getting a different shaped plug. You also need to make sure that the you are using the correct voltage. Voltage on American circuits is different than that offered in other countries, particularly European nations. Apple's range of devices, including the iPhone, are built for easy use abroad and the power adapters they are supplied with adapt to international voltage requirements. Typically, all that is needed is the alternatively shaped plug. This may not be the case with alternative or third-party adapters or chargers. To be sure they will work and not overload your iPhone, look for the words "100-240 VAC" on the charger.