4.2 Phone selection
To choose a phone that would act as the hub of each monitoring
system, several Android phones were tested. Principal
requirements were low cost, boot-on-charge capability, GPS signal
quality, third generation (3G) connectivity and good battery life.
Boot-on-charge capability was fundamental to achieve the design
goal of autonomous operation for SEMS; a phone was required
that would boot up automatically (without human intervention) in
a situation where it had run out of battery (for any period of time).
Restoring the power supply (i.e. attaching a charged bike battery
to the e-bike) needed to automatically initiate the recharging of the
mobile phone, but also to reboot the phone and launch the SEMS
app. This was to cover situations where the participant may run
down the bike battery or remove it from the bike, causing the
phone to run out of battery. An initial design using mobile phones
that do not reboot created problems in real-world use, for example,