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(Battery Solenoid) - Applicable to all homebuilts. Continuous duty. 12V and 24V.


  • High current capacity control
  • Isolated or grounded coils
  • Enclosed in dust-resistant case
  • Longer steel encasement permits lower heat rise and more sensitive operation on Type 71


  • Dielectric Strength: 500 Volts
  • Temperature Range: -40F/-40C to 122F/50C
  • Mechanical Life (no load): 250,000 operations
  • Electrical Life (rated load): 100,000 operations
  • Mounting Position: Recommended mounting with cap down
  • Vibration: 5 gs vertical and horizontal planes
  • Weight (approximate): Type 7014.0 oz.
  • Duty Cycle: Continuous
  • Hardware Torque Specification: Contact Terminal: 45-55 inch-lbs, Coil Terminal: 12-18 inch-lbs.
  • Mounting Bracket: 100 inch-lbs. max (a backup wrench must be used to hold the bottom nut stationary during installation)


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Showed up with the nuts and washers needed to make the connections and it works perfectly. The insulated portion for mounting allowed for 1/4 carriage bolts to be used. Came in handy getting it mounted, only needing a single wrench to tighten it down. Battery side clearly marked.

Bob H
May 30, 2019

My master relay malfunctioned at an airport 70 miles from my home base. I couldnt start my engine, consequently I had to leave the plane their for the weekend. I ordered this replacement and it was promptly delivered in a couple of days. Once installed my engine fired up and I was able to fly home. Thanks Aircraft Spruce!

Michael M
January 17, 2019

In 60F ambient, after about 20 minutes, the unit measures 140F. It was drawing .8 amps at 13.8 VDC.

Mike S
November 19, 2018

Regarding p/n 11-03161, be aware that with the master relay in the battery positive lead circuit, as is commonly done, to actuate the relay coil you must provide a negative/ground connection to the coil terminal (not a positive) from your master switch or key switch. If this is inconvenient, a small control relay can be used to actuate the master relay, activated by the master/key switch.

Gregory A
July 27, 2018

June 5, 2017

First one sent failed the first time we booked it up. Intermittent. We had to tap on it to get it to work. Still waiting on a credit. Ordered 2 more, because they are specified in the stc we are using and I now dont trust it.

Daniel O
August 4, 2020


Q: For this part, is it correct ground the insulated case and use +12 to engage the relay. ( connected to the control terminal)?

Per the manufacturer, the answer is no. The terminal going to the coil is the negative side and should go to the master switch, and the positive side of the coil is common to the power terminal.

Q: What is the peak amperage rating, and the constant amperage rating?

Regarding part number 11-03161, the maximum inrush rating is 150 amps and the continuous duty rating is 80 amps.

Q: Does the coil of the relay have a diode to prevent any excess voltage spikes (as recommended by Dynon)?

Per the manufacturer, no it does not. Regarding part numbers 11-03161 / 11-05799.

Q: Is there a drawing available for these master relays? Specifically one that shows the terminals. Thanks.

We have added the drawing to the "Documents" tab of this web page. Please review it there.

Q: What is the current draw of the coil in amps?

The 70-111226-5B1 is a 12V continuous duty solenoid, so therefore the coil is rated at approximately 9 watts. Since P= IV. Or, 9=I (12). So for a 12 volt system, the current is 0.75 amps

Q: Can this relay be used in series with the starter circuit with a series Starter relay?

No, because the starter circuit requires high amperage we do not recommend using this relay.

Q: Does this relay can replace Cessna part 0850469-1?

No, these master relays are intended for use on experimental aircraft only.

Q: There are 2 images shown, one with 2 relay terminals and the other with 1. Which one do you receive when you order the 12 volt relay?

The single terminal version is the 12 volt. If you click for the full size image, you will see each image is watermarked with the sku for that product.

Q: Is there a recommended mounting orientation for the solenoid?

"Recommended mounting with cap down" per TDS.

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