This paper addresses two problems which may occur during the operation of a MTM-HF traction battery charger produced by the company MicroPower AB: Firstly, high-power traction battery chargers are chiefly supplied from rectified 3-phase mains electricity, making them susceptible to resonant disturbances which occur in high-inductance power lines. These resonant disturbances increase the amplitude disturbances of the rectified DC voltage supplied to the battery charger, thus interfering with its operation. A method to suppress the resonant disturbances was devised using the inherent capability of a battery charger to draw a controlled current from the power lines. Secondly, Battery chargers operating near their maximum current capabilities are strongly affected by the ripple of the rectified supply voltage. In order to fully use the power supply, a control system was designed which minimizes the effect of that ripple on output current while ensuring that the desired value of output current is reached. Both of these methods were successfully tested using a simulated model of the MicroPower MTM-HF battery charger.