This article initially appeared in PS 787 (Jun 18) page 24-25.
Operators, if your aircraft has the AN/APX-123/123A receiver-transmitter, NSNs 5895-01-539-9151 or 5895-01-628-5190, and the newly replaced SAFT* battery, NSN 6135-01-529-0122, (PN A3308909-2), won’t clear the low battery indicator, don’t fret.
Addendum 1 to aviation maintenance action message (AMAM) GEN-16-AMAM-04 is the place to go. It provides additional instructions that address the low battery indicator problem.
SAFT batteries are identified by a black label with white lettering
You need to check out the Notes and Steps 11-13 on Pages 2 and 3. After installing the battery:
11. Re-install the cover with the four captive screws.
NOTE: The red LOW BTRY LED will stay lit after replacing the battery cover. To clear the indicator, briefly press the ZEROIZE button.
NOTE: Briefly pressing the ZEROIZE button initiates a built in test (BIT) similar to the Power-Up BIT (PUBIT). It also zeroizes the crypto keys, if loaded.
12. Clear the red LOW BTRY light by briefly pressing the ZEROIZE button on the front panel. It may be necessary to press the ZEROIZE button several times at one-minute intervals between each cycle to burn off passivation from a stored battery. If you’re not successful after four cycles, replace the battery assembly again by repeating steps 6-13.
NOTE: If the LOW BTRY light doesn’t go out, the battery may not be installed correctly or the battery voltage may be below the low battery light threshold.
13. Make sure the LOW BTRY light goes out after completion of the BIT.
NOTE: Aircraft with the AN/APX-123A must wait 30 seconds after briefly pressing the ZEROIZE button to ensure the LOW BTRY light remains off.
Download GEN-16-AMAM-04 at (you'll need your CAC to access):
For a copy of the addendum, go to (also requires CAC):
You should never attempt to check the voltage of the battery because the fuse is sensitive and may blow. The transponder has the ability to test the battery voltage during the abbreviated PUBIT by briefly pressing the ZEROIZE button. It will indicate the result using the LOW BTRY light.
If your battery won’t clear the LOW BTRY indicator, even after following this procedure, submit a product quality deficiency report (PQDR) using the Product Data Reporting and Evaluation Program website at:
If you don’t have a PDREP account/user ID, follow the steps outlined at:
Need help with the CECOM PQDR process? Contact the CECOM PQDR team at: