I would think that it would be pretty simple to put together a small permanent magnet back-up alternator to go behind the accessory pulley. If enough folks are interested, I think I could come up with something.

If you think about it, the very basic back-up alternator can be pretty simplistic. It just has to be powerful enough to get you to the nearest airport. Thus, it really only has to put out full power at cruise RPM, and it doesn't have to put out much more than a trickle at idle. This could make it quite compact and would likely reduce the cost as well.

To keep it simple, the regulator could be set up to automatically pick up the load at, say, 13.5 volts. It could have a warning indicator that lights when it starts producing current to let the pilot know that there is something amiss with the regular charging system and that loads on the electrical system should be reduced.

>>> Measuring amps require for running, etc <<<

Being an electric vehicle type, I have a DC clamp-on ammeter. I use it constantly. It would be the ideal tool to use to measure the current draw for each of the loads on your airplane. It would also be useful in load testing (capacity testing) your battery. You can get one used for about $100. New, they cost about twice that. Be careful to get one that measures DC amps, (not just AC)

Here is a link to the LEM LH410 clamp-on:

http://www.leminstruments.com/cgi-local/SoftCart.100.exe/online-store/scstore/p-LH410.html?L+scstore+cnld9455ff3c8a3c+1096744982

It costs about $200.


Bill Dube <LED@Killacycle.com>
http://www.killacycle.com/Lights.htm