NavList:

Gary, thanks for the clarification.  I was thinking that was how it would work - I think I just need to get a power supply that can drive enough current to the electronics so that it does not shut down once the 2 minute period is complete.

Just to clarify, what my sextant is doing is:
      - apply power to averager, LED digits light up with 00 showing
      - hit the start button and the digits start counting up (increment by 1 every 2 seconds)
      - I run the index up or down 30' when the LEDs show "30"

      - when the LEDs show 60, I see an LED flash at the top or bottom of the display, but then the display shuts off

      - attempting to hit the RESET button has no effect on the display, but disconnecting the power and then reconnecting it does bring it back to 00

The DC-DC converter I have claims it can supply up to 1A sustained.

The USB battery I have does not state a current drive capability - I have ordered one that claims to drive 22.5W out of a 5V USB port which should be north of 4A.  Hopefully this solves the problem.

The other possibility is that there is a short in the electronics that only gets switched on after the averaging is complete.  I am hoping that this is not what is causing the problem.

If anyone has any other diagnostics to run that might help, I'd love to hear them.

Thanks!

- Art