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[aprssig] PCSAT2 Low Power Shutdown

Robert Bruninga bruninga at usna.edu
Wed Apr 19 16:07:23 UTC 2006


PCSAT2 shut down due to low power as the ISS
attitude is approaching maximum beta angle.  Last 
packet was at 14.6 volts at 2052z on 17 April.

Volts where headed down at .3 volts per day since
about the 13th.  At 0300z on the 19th I attempted
to restore on a good overhead pass and was 
unsuccessful.  Apparently when the 120 hour 
reset occured, and after the 8 hour EVA timer,
then the low-V shunts kicked in and rapidly took
the battery down to the 12 volt limit from whence it
would have continued its .3v per day decline and
gotten to the low-V cutout.  (PCSAT2 stops operating
at about 11.? volts.)

We will have to wait until good sun returns about the
28th before we can restore PCSAT2. 

Bob Bruninga
USNA Satellite Lab






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