As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
EMERGENCY LIGHT BATTERY PACK M1673 DOES NOT PASS A CAPACITY FUNCTIONAL CHECK. (AFTER A DEEP CYCLE). GROUNDED - YES. REMOVED AND REPLACED M1673 EMERGENCY BATTERY PACK AND PERFORMED A GOOD M1673 BATTER EMERGENCY INSTALLATION TEST PER B737-900 AMM 33-51-06-960-805 STEP 4.