I am building a GS P-51; I will be using the 'Power Expander Sport Plus' with two 6 Volt NiMh packs for Reciever/Smart Fly Panel; I will have 2 manual switches, one for each battery in a fuselage compartment, so I can actually cut off the battereies to the Reciever/Smart Fly Panel; I will also be using the Pin/Flag Fail safe switch. The problem is the Ignition battery, which will be a single 4.8 NiMh pack located in the engine compartment; I would love to be able to install a 3rd switch in the Fuselage Compartment, to be able to cut off the battery to the Ignition Module; however, I don't want to run a chance of any radio interference by having the wires running from the engine compartment to this switch; is a manual cut off switch for the Ignition battery nessesary, I am trying to eliminate any unsightly switches on the surface and I don't want to have to build another compartment, I plan on installing a small charge port up front to be able to charge the ignition battery without having to remove the cowl; if an actual mechanical Ignition ON/OFF switch is recomended; can another Smart Fly Pin/Flag switch be some how modified to be used as an ON/OFF switch; as it is extremely unobtrusive.

Thanks, Doug.

Well you could use a smartfly optical cut off on the ignition that way you won't need a mechanical switch.
But you will have to have a charge port.

Not sure what you mean; I will be using the Smart Fly Optical Ignition Cut Off, it comes with this Smart Fly Power Expander; the Smart Fly Ignition Cut Off Receiver normally goes between the the Engine Ignition Module and a Mechanical Ignition ON/OFF Switch; I am just trying to eliminate this Mechanical Switch.

Hi Doug,
I do not use a switch on my ignitions any more. I just use the Cutoff receiver module as the switch. The module will draw a few milliamps a day from the battery in the off position. I disconnect mine when I am home to charge anyway. I don't think you would have a problem unless you left it for a long time without disconnecting or charging.

The problem is that this is a warbird and the ignition battery will be in the Engine Compartement closed in by the Cowl; to disconnect the Battery would be a pain because you would have to remove the Cowl to do so, and I would like to avoid placing a switch on the surface, however; your Pin/Flag switch is so unobtrusive; leaves a small footprint on the surface, no more than an earphone jack, is there a way to modify it to work like a ON/OFF switch by inserting the pin.

Doug.

Hi Doug,
Sorry, the contacts in the Pin & Flag failsafe switch can only handle about 50 milliamps, no where near what you need for an ignition. If you really need a switch I would mount one inside as far forward as you can get and away from the receiver wiring but still accessible. I would not worry about ignition noise as long as you don't have the ignition wires and receiver wires on top of each other.

Fromoco's "Badger" pin type failsafe switch is rated at 15 amps

Hi Larry,
That is true but it is also the size of a JR heavy-duty switch which I think Doug was trying to avoid. The Badger switch uses the pin switch to turn on/off some FET transistors that actually pass the current. The pin switch does not pass any current itself.

Oh, I was not aware of any other pin switches & don't know what FET transistors are []
Sorry I will be ritiring to my room to get my foot out of my mouth

Hi Larry,
Don't worry about it. I was just trying to explain why the Badger can handle 15 amps but my pin cannot. A FET transistor is a "Field Effect Transistor" (redundant, huh). They have a very low resistance when turned on and are excellent for use as switches of high currents.

Robert;

Appreciate the info; I think what I will do is put a small charge port on the surface somewhere up front, and mount a switch on the inside of fuselage, as far up front as you suggested; so when I take the wing off, I can turn the ignition battery off then, and if I need to do a field charge I can charge through the port, I will get a battery pack with 2 leads, one for the switch and the other for the charge port, any problem doing a field charge this way and having the battery still connected to the Smart Fly Ignition Receiver because the switch would be on until I remove the wing?

Hi Doug,
That should work just fine.