Electronic devices are devices such as a mobile phone, tablet,
laptop and digital camera. Some devices use standard consumer
batteries, while others use proprietary batteries, which can be
replaced by the consumer or not. Many devices using standard
consumer batteries integrate the battery recharge function, while
some don’t, so that the battery has to be recharged externally. A
wide variety of rechargeable batteries are in use in electronic
devices including alkaline, lithium-ion, nickel-cadmium, nickel-
metal hydride and nickel-zinc batteries. Thereby, the general mar-
ket tendency in electronic devices is a shift towards lithium-ion
batteries.
The battery capacity in electronic devices ranges roughly from
few to 100 W h. For instance a smartphone has a battery capacity
typically in the range of 5–10 W h, while a tablet stores 20–
50 W h and a laptop 50–90 W h. The battery allows typically for
a non-stop use of several hours, which translates in practical terms
to roughly a one day use. Most standard consumer batteries have a
capacity in the range of few to 10 W h. This paper doesn’t consider
the use of a laptop. The considered energy demand for electronic
devices is 50 W h/day.
Recent developments have shortened the charge time of elec-
tronic devices notably. For instance, a new generation smartphone
could be fully charged within 2 h. Charging is initially fast and
slows down once the battery has roughly achieved 80% of its
capacity. As a battery charger for small devices a power-pole to
USB converter could be used. The input voltage range is commonly
10–32 V DC and the output is 5 V DC, providing a current up to few
amperes. In this paper it is assumed that the recharge of electronic
devices takes place after sunset with initially 20 W power during
the first hour and 10 W during the next 3 h.