Which of the following statements is true regarding ELT battery maintenance?

• A. Rechargeable: replace after 1 hour of use; Non-rechargeable: replace after 50% life; Both: replace after half life
• B. Rechargeable: never replace; Non-rechargeable: replace after 90 days; Both: replace after full life
• C. Rechargeable: replace after 5 hours; Non-rechargeable: replace after 25% life; Neither: no replacement required
• D. Rechargeable: replace after 2 hours of use; Non-rechargeable: replace after 75% life; Both: replace after full life

Answer: (A)

The main idea is to keep the ELT’s power source reliable by replacing batteries based on how they wear out, not just on a clock. Rechargeable ELT batteries lose usable capacity with each charge-discharge cycle, so after a relatively small amount of use (about 1 hour of operation) you should replace them to ensure they’ll deliver sufficient power if you ever need to activate the ELT. Non-rechargeable (single-use) batteries have a finite overall life regardless of use, so replacing them after a portion of their rated life has passed helps prevent a failure when you need them most—so about half of their expected life is a sensible trigger. The idea that you should replace both types after half of their life keeps confidence high that the unit will function in an emergency, rather than waiting until the end of life. The other options imply impractical or unsafe schedules (never replacing rechargeable, very short or very long intervals, or waiting until full life), which do not align with maintaining reliability.