Yes. Batteries with a capacity lower than 27,027mAh (100-watt hours) can be taken on board airplanes legally and safely.
However, government and commercial guidelines are subject to change so we recommend confirming with your airline prior to the date of flight.
All external batteries with a capacity lower than 27027mAh (100 Watt Hours) can legally and safely be taken on board airplanes. To calculate a battery's capacity in Watt Hours: (Battery Capacity(mAh)*3.7)/1000.