Phone charger
From Tardis Wiki, the free Doctor Who reference
Phone chargers were used to power mobile phones. (TV: A Town Called Mercy)
After her daughter disappeared while walking up the aisle during her wedding, Sylvia Noble attempted to phone Donna, only for her mobile to run out of battery power, leading Sylvia to ask if anyone else had a charger. (TV: The Runaway Bride)
Rory Williams accidentally left a phone charger in one of King Henry VIII's en suites. (TV: A Town Called Mercy)
