How to Use a Solar Power Bank
As a rule of thumb, divide the battery capacity of the solar power bank by the phone''s battery capacity. This can give an approximate number of times your phone can be charged using the power bank. For example, if your power bank has a 20,000 mAh battery pack in it and your phone has a 4,000 mAh battery. 20,000 ÷ 4,000 = 5 full charges
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