Narrative:

Battery charging alert followed by a battery discharging alert followed by both alerts extinguishing, and battery low alert displayed. Battery voltage rapidly decreased throughout events to six volts. We landed with five volts. Crew followed flight man procedures and contacted company dispatch for diversion to nearest suitable airport. ZZZZ was chosen by crew. Dispatch agreed. Dispatch alerted ATC as did the crew for the diversion. Flight man 3 was then noted for landing at a suitable airport. Company then radioed that the ZZZZ landing was not required and the captain accepted their reasoning based upon conversation with and research of maintenance controller. Overflew ZZZZ and landed at ZZZ1. Batteries and charger found warm. Casings wet. Conflicting maintenance manuals, and flight manuals. Thermal runaway procedures need clarification and immediate attention. Flew 2 to 2.5 hours with dead battery. Callback conversation with reporter revealed the following information: the reporter stated the first alert he received was main ships battery charging alert followed by a battery discharging alert then followed by both alerts extinguishing and finally battery low alert displayed. The reporter said the battery rapidly dropped to six volts. The reporter stated dispatch and maintenance were advised of the battery situation and the maintenance manual and flight manuals were consulted. The reporter said one manual stated to land at a 'suitable airport', and the other manual stated to land at the 'most suitable airport.' the reporter stated the flight continued to its scheduled destination airport the 'most suitable airport.' the reporter said the battery indicated 5 volts on landing. The reporter said the battery charger and battery were replaced.

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Original NASA ASRS Text

Title: AN MD-11 IN CRUISE AT FL290 OVER WATER 700 MILES FROM IT'S DEST ARPT HAS BATTERY CHARGE ALERT FOLLOWED BY BATTERY DISCHARGING ALERT. BATTERY RAPIDLY DISCHARGED TO 6 VOLTS.

Narrative: BATTERY CHARGING ALERT FOLLOWED BY A BATTERY DISCHARGING ALERT FOLLOWED BY BOTH ALERTS EXTINGUISHING, AND BATTERY LOW ALERT DISPLAYED. BATTERY VOLTAGE RAPIDLY DECREASED THROUGHOUT EVENTS TO SIX VOLTS. WE LANDED WITH FIVE VOLTS. CREW FOLLOWED FLT MAN PROCS AND CONTACTED COMPANY DISPATCH FOR DIVERSION TO NEAREST SUITABLE ARPT. ZZZZ WAS CHOSEN BY CREW. DISPATCH AGREED. DISPATCH ALERTED ATC AS DID THE CREW FOR THE DIVERSION. FLT MAN 3 WAS THEN NOTED FOR LNDG AT A SUITABLE ARPT. COMPANY THEN RADIOED THAT THE ZZZZ LNDG WAS NOT REQUIRED AND THE CAPT ACCEPTED THEIR REASONING BASED UPON CONVERSATION WITH AND RESEARCH OF MAINT CTLR. OVERFLEW ZZZZ AND LANDED AT ZZZ1. BATTERIES AND CHARGER FOUND WARM. CASINGS WET. CONFLICTING MAINT MANUALS, AND FLT MANUALS. THERMAL RUNAWAY PROCEDURES NEED CLARIFICATION AND IMMEDIATE ATTENTION. FLEW 2 TO 2.5 HRS WITH DEAD BATTERY. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE FIRST ALERT HE RECEIVED WAS MAIN SHIPS BATTERY CHARGING ALERT FOLLOWED BY A BATTERY DISCHARGING ALERT THEN FOLLOWED BY BOTH ALERTS EXTINGUISHING AND FINALLY BATTERY LOW ALERT DISPLAYED. THE RPTR SAID THE BATTERY RAPIDLY DROPPED TO SIX VOLTS. THE RPTR STATED DISPATCH AND MAINT WERE ADVISED OF THE BATTERY SIT AND THE MAINT MANUAL AND FLT MANUALS WERE CONSULTED. THE RPTR SAID ONE MANUAL STATED TO LAND AT A 'SUITABLE ARPT', AND THE OTHER MANUAL STATED TO LAND AT THE 'MOST SUITABLE ARPT.' THE RPTR STATED THE FLT CONTINUED TO ITS SCHEDULED DEST ARPT THE 'MOST SUITABLE ARPT.' THE RPTR SAID THE BATTERY INDICATED 5 VOLTS ON LNDG. THE RPTR SAID THE BATTERY CHARGER AND BATTERY WERE REPLACED.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.