Key Features and Benefits:


Key Specifications:


System Requirements          

 +12V system

  low side master relay switch



   Engine Run Switch (optional)

         Master Switch



               Master Relay       5A max

         Warning Light      1A max



  Operating              11.2 mA

  Shut-off                  0.6 mA



               2.65 x 1.45 x 0.85 inch



               0.8 oz  



Never again return to the airport to check the master switch or find a dead battery.  Install the Master Minder instead.


The Master Minder is designed for +12V aircraft, boat or vehicle equipped with a low side (ground) master relay switch. A simple 4-wire interface connects the Master Minder to activate a warning light and automatic master shut-off. 

The system requires no pilot/operator interaction.   The Master Minder will only arm when the master switch is “ON” and the engine is running. 

While the engine is running the warning light will not be illuminated and the Master Minder automatic shut-off feature is disabled.

When the engine is subsequently shut down the armed Master Minder will continuously illuminate the warning light for a period of four-minutes reminding the pilot/operator to turn the master switch “OFF”.  If the warning is ignored the warning light will begin to flash for an additional minute before overriding the master switch by disconnecting the master relay and system battery.

Before the engine is running, the un-armed Master Minder will not impose any time limit for ground operations such as pre engine start checks or clearance deliveries. 

During this time however, the Master Minder will continue to monitor the battery status.  If the battery should continuously discharge below 11.0V for a period of four-minutes, the warning light will begin to flash. The warning will continue to flash for an additional minute before disconnecting the master relay guarding against total battery discharge and potential battery failure.

The master switch “OFF” position is fail-safe as the Master Minder and master relay are completely disconnected with no drain on the battery. Installations, using the automatic master disconnect feature, must incorporate an auxiliary emergency master “ON” switch to override any undesirable Master Minder shut-off conditions.

The Master Minder is manufactured with high reliability components and materials designed to meet aircraft environmental conditions.