The power supply of the Tobii C-Series (for the device models C8, C12, C15) operates at 24 Volt with a maximum of 3 Ampere. This means the power supply will provide a maximum of 72 Watt which corresponds to 72 Wh maximum power consumption. The exact power consumption is very dependent on the use case, the screen brightness, etc. but in normal use the device will consume much less power than that. The power board of the C-Series is designed to use, depending on situation, running processes and connected accessory, between 1.5 and 3 Ampere. The batteries will charge slower or faster depending on how much power the processes running on and accessories connected to the C-Series device use. The C-Series will never use more than 3 Ampere provided by the power supply though. As a comparison, a regular LED flat screen TV can consume around 130 Wh.