Spare a thought for the attendees of the CES tech show who decided to briefly leave their phones in charging towers. The devices got locked inside when a power cut plunged the exhibition hall into darkness. Having to constantly keep personal devices charged is a nuisance we are all, by now, familiar with. Even device-makers are frustrated. During Huawei's press conference, the firm's chief executive acknowledged that battery life was among the top complaints customers make about smartphones.