[aprssig] balloon tracker

Jason Winningham jdw at eng.uah.edu
Wed Mar 2 13:57:55 CST 2005

On Mar 2, 2005, at 12:48 PM, Scott Miller wrote:

> What brand/chemistry were you using?

Energizer e^2 lithium AA.  Spec sheet says good to -40C, but doesn't 
give a voltage vs. temperature curve.  I was driving the transmitter 
and amp directly with 6 of these in a nominal 9V battery, as well as 
driving the OT's built in regulator.

>   Are you sure it was the batteries freezing that killed it?

Not absolutely sure, but I can't think of anything else.  The output 
looked like this:

09.0V 24C
... and a short while later, we were getting
08.7V 01C
... and not too long after that the last packet I got was

When it came back, it started at 08.1V-01C and the voltage climbed back 
up to 9.0V.

It's entirely possible that they didn't freeze entirely, but the 
voltage got so low that the transmitter didn't have enough to drive it.

For this reason as well as size and weight, I need to do a DC-DC 
converter and just drive the rig from two or three of these.  Just 
haven't had time...  If I don't have time before the next flight, I may 
use a 12V pack instead of a 9V, and hope the voltage stays high enough 
to suit the transmitter.


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