Restarting dual Pmags

[jeffkersey]

I think you could easily add a 9v battery to the p-mag, put a switch on it. In the event it does not spark, flip the switch and it will spark... from what I have been told, back country pilots have used 9v batteries have been used to hand prop when starter battery was dead...

[Carlos151]

Originally Posted by cojaken

I have been searching for discussions on "robustness" of dual Pmags, that is, dependability in all.

Bill Harrelson completed his around the world flight over the poles in his Lancair with dual eMags. That’s likely one of the most brutal tests for an ignition system, let alone the complete engine package, with extreme hot and cold temperatures along the way.

They work, they weigh less than a mag, much easier to time, cheaper/better spark plugs, easy to install, self powered once started.

[Desert Rat]

Originally Posted by jeffkersey

I think you could easily add a 9v battery to the p-mag, put a switch on it. In the event it does not spark, flip the switch and it will spark... from what I have been told, back country pilots have used 9v batteries have been used to hand prop when starter battery was dead...

I've heard the same thing and have thought that might be a cool feature. But I was talking to an avionics guy who used to work for brand G and now runs a shop that does extensive work with with experimental aircraft. I asked him his opinion on including analog engine monitoring in the event you needed to jump start, hand prop, whatever.

His take was that it was cheaper and lighter to go all glass and add a $200 backup essential battery to run that stuff, in which case you have a backup source for energizing your p-mags without messing around with 9v batteries etc.

If I was planning on an analog solution I'd re-visit the 9v feature just because it's kind of a neat idea, but he convinced me that starting from scratch, theres a cheaper/lighter/better way that doesn't give up functionality or redundancy.

[William Slaughter]

Have you tested the rpm needed on your plane? I need at least 1000 RPM on mine.

[climberrn]

800 RPM on both of mine.

[pa38112]

No one has answered the OP's question: Will the engine windmill at 800 RPM ?
I do not know the answer, but my guess is yess, in a slight dive. This sounds like agood thing to test hight above the pattern.
My duel P-mags externl power supplyand my digital tach are both tied ito my master, so I would not be able to check my engine RPM, but I would find out if I can get a re-start.

[cojaken]

Thanks everyone for your observations, which greatly helped my thinking process, resulting in a decision to go with the second Pmag.

I ordered it on Monday and it arrived Tuesday! They are no longer gold colored, but black, The removal of the gold has not reduced the price :-)

I am intrigued by the idea of using the EFIS backup battery as backup power for the Pmag. Anybody have an electrical schematic addressing that?