When new hardware is developed, it is often convenient to test the prototype in a Hardware-in-the-Loop Simulation (HILS). In this technique, the critical parts of the system including the hardware-under-test (HUT) are physically present while the rest of the system is emulated in real time. In this paper, a battery emulator (BE) is implemented to replicate the behaviour of a battery pack in a HILS experiment. For this purpose, a remotely controlled DC power supply is used, combined with external passive elements to allow two-quadrant operation. The emulation fidelity is validated through experimental comparison with a real battery pack under constant and pulsed current loads. These experiments show the importance of the impedance connecting the BE to the HUT and how a poor selection can cause oscillations that would not exist in an experiment with a real battery pack.