DC motor Snubber / Kickback protection

My project is using a 12vdc motor that draws between 2 - 3 amps. I need a snubber to protect my relays that reverse the motor. I want to use a simple resistor & capacitor in series. Can anyone help me figure out what components I need?

Also, will this even work considering I will be reversing the polarity?


Yes, it will always work. I use 47 ohm and 100nF for a simple switch/activator/motor with low voltages. I'm guessing that it will also work for you. The 100nF should be able to handle the current peaks and voltage peaks in both directions of course. Perhaps you need more than one snubber circuits.

Do you have protection diodes ? If not, please show us a schematic (you can draw it with a pen and make a photo of it).

OK, my sketch (ICarV10.ino) is attached below, it is a slightly modified version of Steven Cogswell’s Relay Shield Library using the Relay Shield found here
Pins 4-7 control the 4relays & pins 8-11 sense the push buttons which use the arduino’s 5v & a resistor to ground

Thanks. You are using the relays as a H-bridge. The disadvantage is that you can not let the motor free run. When both are low or both are high, the motor is shortcut which causes it to stop faster. Some call that even a brake. So you can either run it full power, or apply the brakes.

That snubber circuit will help a lot. You don't use a mosfet or transistor, therefor protection diodes are not needed. And I think you don't need a snubber circuit over every relay contact. That snubber next to the motor should fix the voltage peaks.