In the end what is "220V Cooling Fan", while axial fan DC fan with fan and what's the difference? In simple terms, the DC fan is a DC voltage and electromagnetic induction, the electrical energy into mechanical rotation so as to drive the blades, collectively DC fan. It relies on the coil and the IC constantly switching from driving blades rotating magnetic induction. "220V Cooling Fan" driving DC power supply is necessary! Voltage DC power supply used must be marked on the fan operating voltage of the same. Battery is a DC power supply, if using it to drive the DC fans, in addition to the charge depends on the battery voltage outside is consistent with the "220V Cooling Fan" operating voltage. If not necessary to use DC / DC converter of the voltage becomes consistent .