X-Mozilla-Keys:                                                                                 
Ken Powell wrote:

     And the answer is:  use 1 alternator and 2 RG batteries, replacing the
     oldest battery during the Annual.  Just like Tracy showed us in his
     newsletter.  AH, but now I am educated and understand WHY, so I can
     sleep at night.  Thanks to all of you for your input. (I still like
     the idea of having a backup alternator but I am not sure it is worth
     the weight.)

A RAT is no big deal. Take any 12V  brush type DC motor and put
a model airplane propellor on it.
Stick it out the window of your car and wire it to
a six ohm, 25 watt power resistor (2 amps). Wire in a voltmeter
and an amp meter. Go out at night and drive 100 MPH some place
and have some one write down the numbers. Note the prop pitch
and diameter. Try different model airplane props and another
six ohm 25 watt power resistor in parallel with the first.

Better yet get a rad fan and stick it out the window.
Take some data and report back.

You don't even need a second battery. You can use
a large capacitor across the RAT and a solid state 
$5 linear regulator or zener diode to keep the voltage
down to less than 15 volts.  Disconnect the offending shorted
battery entirely from the circuit. You just need enough juice 
to operate the EFI and ignition until you can land.
Disconnect all other loads. 

Probably only a couple of amps. Right Tracy?

If you want to get really trick use the electric
fan on the radiator and make it do double duty.
RAT and cooling fan.

I will have to think a bit about how to wire it
and so that it will work in both modes. The main trick is
to disconnect the offending (possibly) shorted battery.
 
Paul Lamar
 
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