How long does it take to fully charge PIE? Bagel Labs August 07, 2018 08:43 Updated Follow PIE takes around 2 hours to fully charge with an average 5V DC adapter and the included micro USB charging cable. Related articles How long does the battery last? I am getting different results whenever I take waist circumference measurements. Why is that? When does PIE turn off automatically? How can I change units? Is it possible to change units on the app? Comments 0 comments Please sign in to leave a comment.