I am considering installing a starter motor immobilizing relay inline with the starter setting of the key and starter solenoid.

I recently got a MAH-112-C-4 online.

It has a 30A switching capacity, this seems to be way over specification to me.

Does anyone know what current is actually typically present in the wire from the key to the starter solenoid?

  • most starter relays are 45 AMP AND MOST HAVE FOUR CONNECTIONS INCLUDING MARKED 30 AND 87 Nov 18, 2019 at 10:20

1 Answer 1


Here is more info than you would like http://www.aeroelectric.com/articles/strtctr.pdf

The short of it is that it takes 8-10 amps to hold the solenoid in place while starting but the draw can spike to 30 amps while it is engaging.

This is assuming that the ignition switch is carrying the current for the solenoid, new cars with push button starts and some other applications may have an extra relay in the mix that controls the current to the solenoid. Then it depends on which circuit you are switching.

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