The FLIR C2 Compact Thermal Camera when connected to the PC enables processing of captured thermal images as well as own charging. Using the Apple 15" MacBook Pro (2018) we plugged in the FLIR camera over a USB Type-C to micro-B cable while the Mac was also being connected with its originally shipped Apple 87W USB-C Power Adapter. Starting from a dead battery on the Mac, the entire power charging was seen to take about 120 minutes to near full charge.
At first plugin the Mac pulled current at about 4.5 amps along a 19 volts rail starting voltage to initially charge at around 88.6 watts (19.7 volts @ 4.5 amps). The Mac consumed more power in this early stage of charging for its battery to get some charge as well as to support charging the FLIR camera. When the Mac was turned on 30 minutes later it pulled lesser current to charge at about 69 watts (19.7 volts @ 3.5 amps). The Mac then repeatedly pulled current in between 3.5-4.5 amps for several minutes after which the current ramped down to stabilize charging at around 39.8 watts (19.9 volts @ 2 amps). The current then decreased further to about 1.5 amps in the last 35 minutes of charging before bouncing rapidly when almost reaching full charge on the battery. Over this quick changing current the Mac could be seen to randomly draw up to 89.5 watts (19.9 volts @ 4.5 amps). Click here to download the trace captured by the GRL-A1 power analyzer to see more details on the entire power charging cycle.
We can observe that the Mac uses aggressive power management schemes such that even while the charger is connected to the Mac, the current repeatedly goes up close to 4.5 amps at repeated intervals.