An aircraft battery relay draws 1A or a bit less,
dissipating about 15W, so a device that big shouldn't get
hot. A 50W resistor is about the size of our little finger.
I tried a latching relay, which draw zero, but takes a brief
voltage to flip-flop 'em with a mere pushbutton switch.
Found out two things. One was the spec sheet was deceptive
about its power handling ability. The contact resistance
was too high, and it would cause about one volt drop when
the starter was engaged. We don't need that for best
starter RPM, so watch any substitute, non-aircraft-type
relay.
A latching relay will not fail safe though. If in an
emergency, like where a large current develops which doesn't
pop a breaker, we may just have to wait for things to melt
and hope a fire doesn't start!
Reg,
Fred F.
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