The Dangers of Long DC wires

KDE Direct products come with standard wire lengths that have been tested for safety and compatibility between products. If the total length of DC wire between the ESC and battery is too long, then it will cause higher voltage spikes induced in the wires and on the input capacitors. These higher voltage spikes will cause the capacitors to heat up and cause premature wear on sensitive components inside the ESC.

The best way to solve this issue is to keep the DC wires short and to extend the AC wires between the motor and ESC. Extending the AC wires will not harm the motor or the ESC. Always use wires with an appropriate AWG rating. If extending the AC wires is not possible, then adding capacitance is necessary to compensate for the additional wire inductance.

KDE Direct recommends adding 2.35uF per amp for each inch of DC wire longer than 12 inches. For example, if you have three feet of DC wire between the ESC and the battery: 2.35uF * 85A * 24 in ≈ 4,800uF per ESC is required. Using several capacitors in parallel is optimal for heat distribution and they should be placed near the ESCs capacitors (within 4 inches). If the total DC wire length is longer than 3 feet, then spacing the capacitance every 8-12 inches may be required to reduce the higher inductive load. When selecting capacitors, it’s important to de-rate them and use ones with a low ESR rating.