How long does it take to charge Structure Sensor Pro and (Mark II)?
Structure Sensor (Mark II) and Structure Sensor (Mark II) Pro will normally take ~30 - 60 minutes to charge depending on the type of charger that you use with the USB charging cable.
1.5A @ 5V = ~30 minutes (from a <5% charge state)
0.9A/7.5W @ 5V = ~60 minutes (from <5% charge state)
0.9A can usually be expected from most computers. 1.5A can be expected from most USB wall chargers.
Weaker power sources may cause your sensor to be unable to fully boot, putting it in a confused state that may cause it to charge much more slowly, or not at all. Be sure to connect your sensor to an ample power supply.