I am currently using an 80A automotive relay to control a motor. The relay seems to work great to control the motor, but on disconnect a visible spark can be seen through the clear relay housing. I understand that the spark could damage the relay and I need to prevent it.
Should I use a diode or a capacitor? Also what size/ ratings are required?
Thank you
Best Answer
Assuming it's a 12V DC PM motor (and assuming you're not reversing current to the motor, or allowing the motor to be driven backward from the shaft) you can put a diode across the motor.
Diode PIV rating has to be sufficient to handle any transients on the 12V line. Current rating needs to be high enough to absorb the magnetic field energy in your particular motor under all conditions (including stall).