I carry one of these portable chargers. (see image below). You just never know when your smartphone is going to run our of charge. Well I must admit, I’d struggled a bit with my latest Galaxy S3. Even with  a decent Samsung lead , charging seemed hit and miss. The solution use as short a lead as possible. It’s obvious to any of us that should know better, volt drops and all that. But sometimes we get ‘blinded’ , it’s just a charger after all. Well thanks to the friendly people behind mine (I’ve bought two). They kindly supplied me a spare lead 😉