However, there are severe problems with mobile devices. The cell phone has a limited
talk time and may die in the middle of a con
versation. The mobile MP3 music player
can store a collection of 500 h, but the batteries last less than 24 h. The portable gaming
device has a display that is very diffi cult to read. A laptop only works for a few hours;
after that it just becomes an unusable brick. The GPS locator that ’ s on your wrist can only
measure your position continuously for 4 h on one battery. The above examples illustrate
that battery lifetime is a shared problem for portable devices.
The fundamental components ...
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