Pre-Charge Resistors and Coil Suppression Diodes
Pre-Charge Resistor is a device that slowly charges the capacitors inside a electronic speed controller before it is powered up. Without this resistor, closing the contactor would generate a large amount of inrush current causing the contacts to arc. This arcing can permanently weld the contacts in the on position. The inrush current from not pre-charging can also cause the contact tips to get pitted resulting in a poor connection and diminish vehicle performance.
 |
Battery Pack Voltage |
Resistor Value |
Price |
|
| 24-72 Volts |
240 Ohm - 1k Ohms 10Watts |
$10 |
 |
Coil Spike Suppression Diode is a protection device across the contactor coil. Energizing the contactor coil creates a magnetic field that forces the solenoid arm to engage the contacts. When the contactor is turned off, the magnetic field collapses causing a back “voltage spike” that can damage the controller. The diode safely suppresses this energy.
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Diode |
Contactor Size |
Diode Current Rating continuous |
Price |
|
| 1N5408 |
200A and up |
3 Amp |
$2.50 |
|
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