Mailing List Message #46444
From: Michael LaFleur <>
Subject: Re: [FlyRotary] Re: Battery Isolation diodes
Date: Mon, 15 Jun 2009 09:56:40 -0700 (PDT)
To: Rotary motors in aircraft <>
I particularly don't like to have the pilot disable the injectors at all. But with regard to auto disabling the secondary injectors; any little bit you can help in keeping the engine running, the better. It can be the difference between making the runway, or the ditch before the runway.

In any case, you have to decide what features you want to support. Yes, support time can be overwhelming.

Mike LaFleur

From: Tracy Crook <>
To: Rotary motors in aircraft <>
Sent: Monday, June 15, 2009 12:41:13 PM
Subject: [FlyRotary] Re: Battery Isolation diodes

A technically valid idea but it seems the more features I put in, the more customer support calls I get where I have to explain the behavioral details of the controller.  I average 2 hours a day on these now (not counting email support).  The EM2/3 already has a low limit alarm feature.  I'd rather have the pilot make the call on disabling the injectors.  We are only talking about VERY small difference in endurance if the injectors are the determining factor.

Tracy (leaving in a few days for Colorado [where there are no phones :>)  ])

On Mon, Jun 15, 2009 at 12:29 PM, Michael LaFleur <> wrote:

If you monitor battery voltage in your ECU via a divider network, which I'm guessing you do so you can change injector opening times based on battery voltage; you could also shut down the second bank of injectors if battery voltage gets low enough so as to conserve energy. For those with an engine monitor, you could flash a warning.

Mike LaFleur

From: Tracy Crook <>
To: Rotary motors in aircraft <>
Sent: Friday, June 5, 2009 10:21:15 AM
Subject: [FlyRotary] Re: Battery Isolation diodes

Just one comment about the isolation diodes idea.  I hate it.  It's for my own selfish reason though.  The diodes not only isolate potential faults, they isolate electrical noise from the battery which increases the noise on the rest of the system.   Noise on systems with poor electrical system layout has been my number 1 headache.   These diodes multiply the problem by at least a factor of two.  If you insist on using the diodes, you might want to install a capacitor at your main power distribution point.  Those big electrolytics that the monster car audio systems use would be ideal : )

The electrical systems guru (Bob K.) points out that batteries do not make a good noise absorber and that is technically true but I would counter that they are infinitely better than nothing at all. 


On Fri, Jun 5, 2009 at 7:47 AM, Ed Anderson <> wrote:

Jim Maher was kind enough to convert the large DXF files of my electrical
system to JPG so perhaps more of you can examine it.  Recall I have removed
the 2nd battery stuff - so ignore that on the diagrams.  Also the diagram
does not show any of the detailed EC2/injector/ignition wiring - follow
Tracy's recommendations on that.

As you will note there is no "isolation" diode between alternator and
battery and also that the battery voltage holds the master relay closed.
That is another change I must make.  I must have decided (10+ years ago)
that the battery would never fail - only the alternator.  Clearly (now),
without battery voltage (in my design) to hold the master relay  closed -
when the battery voltage fall to around 6-7 volts (in my case) the relay
opens and all that good electrical power being produced by the perfectly
good alternator - can not reach any part of the electrical system.  Clearly
NOT good as I could have continued to fly perfectly well with just the
alternator juice.

Your design is not going to be any better than the accuracy of your
assumptions.  Clearly some of my assumptions make 10 years ago definitely
need revising.


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