The correct resistor is most reliably selected through an understanding of the pulse energy. The standard resistor power rating is the limit of continuous power that the resistor can handle if held at a specific ambient temperature, very often 25°C. Since precharge is not a uniform or continuous type power cycle, choosing a 20kW resistor is wrong. Moreover, a resistor of this size is tremendously expensive, heavy, and possibly does not even exist. The characteristics of the resistor that are relevant to this design are the pulse energy handling capabilities, which are a determined by the thermal robustness of the resistive element and the ability to sink heat. For this design, a wire-wound resistor is the best option because these resistors have additional mass placed within, known as the core, and often around the coil, which is known as the housing. This additional mass sinks the heat generated from the high-power pulse.

There are several ways to determine if a resistor is capable of the handling the precharge pulse, typically through charts that are included in the data sheet. The first way is through the short-term overload rating. This rating means that for a specified period of time, the resistor can withstand some multiple of the regular power rating. Wire-wound resistors typically have a short-term overload of 5 × or 10 × the rated power for 5 seconds. This can sometimes be extrapolated further and presented as a chart: if a resistor has an overload of 5 × for 5 seconds then the resistor can also be able to handle 25 × for 1 second if the data sheet explicitly says. If the power rating of the resistor is 100W, the overload pulse energy in this scenario is 2500J. This does not mean the resistor can handle 2500J of any pulse length. Too short of a pulse length does not allow the coil enough time to distribute the heat throughout the core and housing, causing the wire to fail.

The second way to confirm the ability of a resistor is through a pulse energy chart. This chart is typically presented with resistance on the x-axis, linear or logarithmic, and pulse energy on the y-axis. The chart relatively straightforward visual that shows the pulse energy limit of each resistor within a family. A third chart to reference is often labeled pulse performance. This chart shows pulse duration on the x-axis and maximum power on the y-axis, both of which are in the logarithmic form.

In the interest of cutting costs, a designer can pursue the smallest possible resistor available that can handle the precharge pulse. In this event, or if none of the pulse information is published, confirm with the manufacturer what the energy limits are for a particular resistor. As the energy limit can change depending on the type of pulse, a designer must confirm the resistor based on a capacitive pulse.