Re: Dreaded Click and NO START Cause/Photo of Relay

Ken Marr

Bob, at al,

That's not carbon, rather, it's copper (II) oxide,  CuO. The poor contact when solenoid closes along with the high current generates significant amounts of heat that causes the copper electrode to oxidize as it reacts with oxygen in the air to generate CuO, a black compound that is a non-conductor:

      2 Cu (s) +  O2 (g) ---> 2 CuO (s)


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