The first time I plugged in one of these it instantly was blinking the 'FL' which is supposed to mean that it's 'full'. However, I unplugged the AC charger and checked it again where it went to under 10% (showing that the battery was far from charged and the 'FL' was a false reading coming just from the charger power … see more The first time I plugged in one of these it instantly was blinking the 'FL' which is supposed to mean that it's 'full'. However, I unplugged the AC charger and checked it again where it went to under 10% (showing that the battery was far from charged and the 'FL' was a false reading coming just from the charger power while the battery was resisting taking any power). So leave it plugged in for 12+ hours and you'll likely see it go down to 60% after a few hours, then slowly come back up and eventually reach 'FL' again. Then it will be charged (and if you pull the plug on the charger and check it, it should still read 99%). see less The first time I plugged in one of these it instantly was blinking the 'FL' which is supposed to mean that it's 'full'. However, I unplugged the AC charger and checked it again where it went to under 10% (showing that the battery was far from charged and the 'FL' was a false reading coming just from the charger power while the battery was resisting taking any power). So leave it plugged in for 12+ hours and you'll likely see it go down to 60% after a few hours, then slowly come back up and eventually reach 'FL' again. Then it will be charged (and if you pull the plug on the charger and check it, it should still read 99%).