Cooling a drum pump motor and/or battery

A drum pump, comprising:

• an inlet for drawing liquid from a drum;
• an outlet for discharging the liquid drawn via the inlet;
• and
• an assembly configured to draw the liquid into the inlet and discharge the liquid out of the outlet, the assembly comprising:
• a motor sub-assembly that includes a motor and a motor fan,
• one or more batteries configured to provide power to the motor, and
• a cooling fan disposed vertically above the motor sub-assembly and the one or more batteries during operation of the drum pump, wherein the cooling fan is configured to draw air in an upwards direction through the cooling fan, thereby dissipating heat from the motor and/or the one or more batteries, and wherein the upwards direction is the same as a free convection direction associated with a density difference between hot air radiating from the motor and/or one or more batteries and surrounding cooler air.