Per the Tello manual (p. 15), you want a "certified USB adapter that is rated at 5V and 1.5A or above," which means the iPad charger @5.1V and up to 2.1A (the battery controls the amperage) should be perfect.
Per the Tello manual (p. 15), you want a "certified USB adapter that is rated at 5V and 1.5A or above," which means the iPad charger @5.1V and up to 2.1A (the battery controls the amperage) should be perfect.