How to calculate power needs:
Volts (V) X Amp hours (AH) = Watt-Hours (This will give you the required watt -hours for your needs.)
Example: 12V x 32AH = 384 watt-hours of power available from fully charged briefcase. If you plugged in a monitor at a trade show that used 30 watts of power and was on for 7 hours, 210 watt-hours (30 x 7) would be the requirement. Since the briefcase has 384 watt-hours available, there would be 174 (384-210) of capacity left on the briefcase.