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Posted for ian.crowe@sympatico.ca:

I have an IO360 with the combined dual magnetos and would very much like to turn it over to full electronic ignition.  Full makes the most sense in this situation I believe as I cannot remove one magneto only.

Light Speed have a system that appears to fit and it would appear sensible to use the direct crank triggering and keep the magneto drive for a possible small alternator, later.  A separate isolated battery would provde back up.  In all the discussions on electronic ignition the question of back up is well to the fore as it should be.  However I note from the Light Speed specifications that current draw for a 4 cylinder engine is 1.2amps at 13.8volts.  This amperage would increase as standby battery voltage falls if it is not being charged.  If we consider a draw of 2.5amps at 6.9 volts which is still above the minimum operating voltage of the ignition system (4volts) then a battery of 10AH capacity would give a theoretical 4 hours with two hours being well within its capacity.  Plenty of time to find an airport and even enough power for limited use of radios and nav.

So I have three questions at least,

1.    Is my theory and calculation wrong?
2.    Why are people quoting pucker up experiences when using a standby battery to get home after the main system failed?  Are their batteries too small? Do their electronic ignition systems draw a lot more power than the Light Speed I have quoted?
3.    What do other users of electronic ignition recommend as a system/manufacturer.

Ian Crowe

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