I recently purchased a Dewalt DCL060 area worklight and decided to measure the current draw so I could calculate the rough battery lifetime. With a lab PSU set to 18V which is the nominal voltage the current draw was 1.37A. Here’s a table of roughly how long it will last for the common battery capacities that I know of:
Capacity (Ah) Battery life (hours) 1.3 0.9 1.5 1.1 2 1.5 3 2.2 4 2.9 5 3.6 6 4.4 9 6.6 12 8.8