Yes, it's completely free and you'll never be charged for it.
Many people aren't aware that a mobile charger with replaceable lithium batteries exist. We're attempting to send them to customers in each U.S. State; we can no longer ship them internationally due to recently-imposed lithium battery shipping restrictions. Otherwise, the entire planet would receive them; hopefully, this will change when its successor is made available to the public.
So why is a solar company providing traditionally-powered devices to its customers?