On 7/29/11 4:51 PM, Tony V wrote:

With modern avionics/electronics you really should not need this. Modern
radios, transponders, etc. have built in switch mode power supplies that
effectively do the same as this device does, but usually more
efficiently.

Thanks, Darrell. The reason that I ask is that after flying for a few
hours with a new 9Ahr battery, the LCDs on my radio (Dittel FSG71M)
blank out when I transmit - which gets out OK. Other than the radio, I'm
only running a Cambridge 302 and an iPaq.

Tony V.

Its hard to see what would be drawing so much power to drop the Dittel
below its speced operating voltage. There was a recall/repair on some of
these radios but I though that only affected the RF board, not sure that
could affect the display like this but I don't know. Was yours affected?
- check here http://www.cumulus-soaring.com/dittel.htm Other Dittel
users can comment if they ever see this display problem at reasonable
supply voltages. I've never owned a Dittel radio.

I'd want to check that the 9Ah battery is not faulty or not getting
fully charged (the charger may be faulty or incorrectly sized etc),
something else/hidden is drawing power or the Ditel has a problem.

It would be nice to do a discharge test on the battery after charging it
as you normally would and see exactly what power it is storing. You can
do this maually but much easier with a discharge tester like the West
Mountain Radio CBT III. Improper charging is not an uncommon
problem-check your charger is the right type, and sized for the battery
and if it has indicators for charge/complete or float stage do they show
as expected (and you still need to leave the battery on charge for many
hours after that to top up the last ~10% or so). But if you can't do
that at least measure the current your equipment is drawing and measure
the voltage under load (all avionics on and transmit key pressed) when
the Ditel starts misbehaving. I have numbers for common toys including
the C302 etc. in slides at http://www.darryl-ramm.com/glider-batteries
I think the radios are speced down to 9V and may work even lower, and
with your setup just should not have problem after only a few hours.

You would not be the first person to have something hidden behind the
panel that is consuming power. Some PDAs can suck interesting amounts of
power ( transponder) esp. if they have a large Li extended battery
packs that are connected to the ship when discharged. A poorly designed
PDA chargers might be very inefficient (but most are not). Still noe of
these alone would really explain this. Maybe you have several things
goign on. Certainly measure the current draw with everything turned on
and see if it makes sense with what is in my slides. Also measure the
current of each device.

Darryl