When operating the motors, the current consumption is very high and the batteries will eventually discharge to the point that the controller's DC/DC converter is no longer capable to generate the supply needed to operate the controller's electronics. It also may happen that the voltage at a weakly charge battery drops to below 12V as motors are started or load peaks. To keep the controller and operating in these conditions, the AX2550 can be supplied with a separate and stable external 12V power source.