Mid-Continent Instruments, Wichita, KS
Rev B May 25, 2004 Manual Number 9015762 Page 14 of 21
2.6 Continued
Airworthiness
1. Recommended replacement interval for the standby battery (P/N 9015607) is 3 years
because of diminished capacity (See Fig. 2.7 for more information). This can be a user
replaceable item if desired. The standby battery contains lead. Recycle the battery in
accordance with state and local regulations.
2. If the 4300-4XX Electric Attitude Indicator has not been operated for an extended period
(more than 3 months) to keep the battery charged, the standby battery should be
charged by one of the following methods.
A. Keep the battery plugged into the 4300 Electric Attitude Indicator. Run the unit
overnight (approx. 15 hours) at the rated voltage.
B. Float Charging: Disconnect the battery from the indicator. Connect the battery
to a constant voltage source (battery plug (pin 1) red wire = positive) of 20.4 to
20.6 VDC continuously. Float charging may take 24 hours or longer to charge a
battery pack. MCI Battery Charger/Tester P/N 36029 may be used to apply an
initial charge. The charger automatically switches to maintain a float charge
indefinitely after initial charging is complete.
C. Routine Charging: Disconnect the battery from the indicator. Connect the
battery to a constant voltage source (battery plug pin 1 red wire = positive) of
21.6 to 22.1 VDC with a current limit of 0.1 ampere maximum. When the
charging current drops to approximately 5mA, the battery is fully charged and
should be disconnected. Leaving 21.6 to 22.1 VDC charge voltage on the battery
for an extended time will degrade its life. If continuous maintenance of the
charge is desired, refer to Paragraph B: Float Charging.
3. A full battery capacity test must be performed at least on an annual basis, as well as any
time there may be a question about battery performance (life).
Full Battery Capacity Test:
A. Disconnect battery pack from the 4300 Attitude Indicator.
B. Ensure the battery is completely charged and at or near normal room
temperatures (20-25°C). (Ref. Sect. 2.6.2)
C. Connect the battery to a load of 90 ohms (rated for 10 watts) for 60 minutes
while monitoring the battery voltage level.
i. If the battery voltage is above 15.0 volts at the end of the 60-minute
battery capacity test, the battery should be capable of continued use
after recharging is complete.
ii. If the battery voltage drops below 15.0 volts before the end of the 60-
minute test period while under load, the battery pack is nearing the end
of its service life and should be replaced.
D. Recharge the battery pack immediately. WARNING: The battery may be
permanently damaged if it is left in a discharged state. Recharge a discharged
battery as soon as possible and maintain with a float charge for maximum
battery life.
4. In normal use, the 4300-4XX supplies the proper float charge voltage to maintain its
battery at peak capacity, however, the battery will slowly self discharge if the attitude
indicator is left unused for long periods (over 4 months) the same as an automobile
battery. To restore a full charge, the battery should be periodically charged per Sect.
2.6.2, or removed from the installation and maintained on a charger such as is available
from Mid-Continent Instruments. (P/N 36029)
5. No other periodic scheduled maintenance or calibration is necessary for continued
airworthiness of the 4300 series Electric Attitude Indicator. If the unit fails to perform to
specifications, it must be removed and serviced by a qualified service facility.
