As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PHX - EEL - DURING 8-DAY CHECK, A LT EMERGENCY POWER SUPPLY UNIT AND BATTERY PACK FAILED TEST. MAINTENANCE REMOVED AND REPLACED THE LT EMERGENCY POWER SUPPLY UNIT AND BATTERY PACK. OPERATIONAL CHECK WAS GOOD. BATTERY PACK INFORMATION: MANUFACTURER: DIEHL GMBH, PART NUMBER: 3214-30.