Frank wrote:
I have been experiencing some intermittant CAI-302a shutdowns, before,
during, and after flights lately. Here's what I have been able to
determine so far



The shutdown appears to be associated with the CAI-302a sensing that
it's input voltage is too low for normal operation. When I have been
able to get the CAI-302 to display power supply voltage, I have seen
numbers as low as 4.5VDC, but typically something like 8.8VDC, just
before shutdown. Switching from the front to the aft battery does not
change the low voltage reading.

I have two brand-new Werker 12V lead-acid batteries, both religously
charged with Battery-Minder Plus chargers, so it is hard for me to
believe that *both* batteries could be loaded down to 8.8V from 12-13
volts without a *lot* of smoke and heat (none detected).

I have eliminated as many loads as I can so far, leaving only the
CAI-302a and my IPAQ 3955 PDA/Cradle (I have plans to eliminate the
PDA & cradle, but haven't done it yet)

The CAI-302a power/data cable appears to be secure at the 302 and at
the power buss.

I have not yet tried to measure the actual 12V battery voltage in
flight, but that's on the list to do. Obviously, this will a PITA, but
do-able.

Any other thoughts? Anyone else ever have this problem?

Regards,

Frank (TA)

Frank,

It may very well be the PDA. If the PDA is trying to charge the battery
it may try to draw enough current through the 302 to cause the 302 to
quit. I had this happen and was able to fix it by adding a box that was
available (think cumulus soaring?) that passes the data through, but
provides independant power to the PDA so that the 302 doesn't have to
provide PDA power. If that's the problem, adding that box will fix it.

Gary