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Task 24-20-10-10 - Inspection of the ETX900 Battery

  • A. Visual Inspection of the Battery
    • (1) Visually inspect the battery for signs of damage - warped or swollen plastic case.
    • (2) Test the fault indicator
      • a. Touch the fault wire output of the battery to ground
      • b. Check that the internal battery LED and the cockpit fault indicatory illuminates
    • (3) Check that the terminal screws are tight
  • B. Do a test of the battery capacity
    • (1) Ensure the battery is fully charged
    • (2) Turn on all electrical loads and start a timer
    • (3) Measure and record the battery's discharge amps using a DC clamp-on current meter at the positive terminal of the battery
    • (4) Using the measured amps in the previous step and the battery's rated capacity, calculate the time to discharge the battery to 80%.
      • a. Time to discharge 80% (Hours) = Rated  Capacity  in  Ah  .8Measured  Discharge  AmpsRated\; Capacity\; in\; Ah\; * .8 \over Measured\; Discharge\; Amps
      • b. ETX 900 Rated Capacity = 15.6Ah
    • (5) If the battery shuts off discharge current before the time expires, replace the battery.
      • a. If the battery has over 50% capacity left, replace the battery within 3 months.
    • (6) Fully Charge the battery. Repeat the test on the other battery as required.