Mid-Continent Instruments, Wichita, KS
Rev B May 25, 2004 Manual Number 9015762 Page 20 of 21
C. Standby Battery Test
The control panel on the front of the instrument incorporates a manual test feature.
This test feature places the standby battery pack under load for approximately one
minute (the gyro is used as a load) while displaying either a red or green light under
the word TEST on the front panel.
To initiate this test, first turn on the indicator with aircraft power and allow the unit
to spin up for 3 minutes or more, then press and hold the STBY PWR button. After
several seconds the amber LED will start flashing, indicating unit has latched into
Battery Test Mode. The test runs for approximately one minute, during which time
the amber LED flashes continuously and either a red or green light is displayed under
the word TEST. Visually monitor the test lights until the amber LED stops flashing,
signaling the end of the test. A green light throughout the test indicates the standby
battery pack is healthy and should be able to function under normal operation. A red
light at any time during the test means that the standby battery is at least in need of
charging, or possibly replacement. Note, however, that a green light throughout this
short test does not guarantee that a full hour of operation time is available. Actual
operation time on the battery may vary considerably depending on temperature,
charge status, and battery condition. (See Sect. 3.6 for more details). Complete
charging may be required to bring the battery up to full charge if it has been stored
for more than four months or if it has been partially discharged. If a steady red light
is observed at any time during the test, charge the standby battery completely, using
one of the methods described in section 2.6.2 and retest the battery. If after
charging, the test still fails, service may be required. (See Sect. 2.6.3 for further
testing).
It is not recommended to test the battery when aircraft power is not available, but it
is possible to put the indicator into test mode while operating on the backup battery.
The test will run, but the indicator will turn off at the end of the test period. To turn
the indicator back on, simply push the STBY PWR button again.
Fig. 2.5: Nominal Battery Discharge Rate at 20°C
