I'm having trouble understanding the ratings for an SPST Relay. I need one with the following specs: Coil Rating: 12Vdc, Contact Rating: 20Amps @ 15Vdc If I use a relay with a 24Vdc Coil rating, does that mean that it would require 24Vdc to operate, or is that the maximum amount of voltage it can handle? Will it work with lower than 24Vdc? Also, I have found one with the following: Coil Rating: 12Vdc, Contact Rating: 50Amps @ 14Vdc I was contemplating using this one because it is 50Amps @ 14Vdc, not 15Vdc. Will I be okay using this relay?