I wanted to know if there is a way to protect the circuit from a relay. Usually you add a backwards diode for protection, because when you turn off the relay, the magnetic field in the coil collapses and tries to keep the current flowing, if there is no escape path, it turns into a high-voltage pulse that can destroy anything connected to the coil, adding the diode bleeds the pulse off to the positive rail before it can do any damage. So now my problem is I have is that I can't access the relay to put a diode protecting the transistor. The relay I have is G5LE-14 DC18, it's datasheet:http://www.kynix.com/uploadfiles/pdf0125/G5LE-14+DC18.pdf. So how can I create a circut that will be able to protect itself from this, the relay is connected to a 12V 40A battery. Can I use a mosfet, or hexfet, or some other combination that can be used to protect the circuit. EDIT: This is what I was thinking but some people said that it can't be done, so I asked on the forum. Relay, I removed the case, but it's still encased in something black, the wires go under and come out of a terminal so I have no idea what's inside.