Summary. The iPhone 4S comes with a faster more power hungry processor. This can result in faster battery depletion than with previous iPhone models. For this reason, it’s helpful to use a battery pack case like the Mophie Juice Pack Plus. [Buy Now] This page, including the video below, provides helpful information about battery life and the benefits of battery packs. Most of the information presented here applies to all newer smart phones.
Processor Intensive Tasks. With the addition of HD (1920x1080p) video recording, it’s now increasingly common for people to use the iPhone 4S as a portable solid-state HD video camera. That means more time in use, and with processor intensive tasks like video recording and editing, the battery level is more likely to deplete. Other processor intensive (and power intensive) tasks include Skype video chat, watching YouTube videos, Siri Voice Recognition, and apps that use the GPS.
Low Signal Conditions. When your mobile signal or wifi (wireless) signal is low, your device is more likely to work harder by boosting its own signal. This can also result in battery depletion.
Convergence and Battery Life. The miracle of the iPhone is that it combines a still camera, video camera, mobile phone, compass, GPS, and a computer with over 200,000 programs available – all in a single small device. It’s a perfect example of convergence. Previously, a person would carry many devices — each having a dedicated battery. Now, with the iPhone, a single battery is used to power the convergent technologies found in the one device. This is another reason why battery packs are popular.