Surviving Flight Recorder Power Failures

On Thu, 16 Jun 2005 09:37:07 -0700, ContestID67 wrote:

I agree that a couple of diodes are the way to go to place the
batteries in parallel without allowing one battery to cause problems
with the other. However the key is the voltage drop which is typically
0.6vdc for a power diode. Do you have a specific diode number that you
have been using?

I used two IN5817's. I only use these to power a Volkslogger. The rest of
the panel is still controlled via "A/B" switches.

These are rectifying diodes with low forward voltage drop, especially at
low currents. In my setup I think I loose less than 0.2V but it is tricky
to measure. These are small diodes with a Max current rating of about 1A.
I don't think that you could power your whole panel through them. (Google
should find you a data sheet).

Having the switches for the heavy current items (transponder etc) is
useful. It is very difficult to test the health of a battery on the
ground. So you normally only discover that the battery is not up to
scratch when it dies while you are flying. At this stage it is nice to be
able to switch over to battery B.


Ian