"karel" wrote in message
...

"Rob Turk" wrote in message
...
"Skrud" wrote in message
.. .
What is the correct type of diode (p/n) to put across a garden-variety
battery contactor to prevent the inductive spike?


Something like a 1N4004 (1A, 400V) should do just fine.

Yep that what's I thought.
But doesn't it depend on the size of garden?

Not really. The size of the chip above the 1N4003 is fairly hefty and
constant as opposed to the size down around the 1N4001. You aren't worried
about carrying reverse currents of an amp or so; what you are concerned with
is single-pulse forward currents of hundreds of amps for a microsecond. The
1N4004 ought to do you just fine until you get to the current level for a
contactor for a railroad diesel engine {;-)


Jim