Maybe one can be interested, I measured my ATIK-383L+ mono camera consumption.
Vent on, camera not yet connected 0.46-0.47A
Vent on, camera connected in MaximDL setup menu, no cooling: 0.34A
Cooling from 23°C to 10°C: 0.5-1.1A
10°C steady : 0.5-0.7A
Cooling from 10°C to 1°C: 1.2-1.5A
1°C steady :~1.0 A
Cooling from 1°C to -15°C: 1.5-1.68A (the max current I experienced through the whole process was 1.68A)
-15°C steady :~1.4-1.6 A (power ~80%)
making a 120" shot: 1.4-1.6A
warm-up from -15°C: 1.6-0.35A
disconnected, USB plug out: 0.33-0.34A
I used standard 12V starter accumulator
Ferenc Varga