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The Boeing Company Message Board

  • falmouthharbor falmouthharbor Jan 23, 2013 11:19 AM Flag

    latest news on batteries

    Japanese investigators who retrieved the charred and disfigured battery pack from the All Nippon plane initially suspected overcharging, a dangerous condition where a battery is charged beyond its electrical capacity and becomes susceptible to overheating and fire. Experts in lithium-ion batteries — the type under investigation on the Dreamliner — have suggested that the batteries may have been charged too quickly, pointing to charging issues rather than problems with the batteries themselves.
    But data retrieved from the All Nippon jet suggested that the battery had not been charged beyond its maximum design voltage, 32 volts, Norihiro Goto, chairman of the Japanese Transport Safety Board, told reporters Wednesday. The U.S. Federal Aviation Administration announced similar findings Sunday from its investigation into the lithium-ion battery that caught fire in Boston.
    Mr. Goto said that readings aboard the All Nippon flight showed the battery’s voltage stayed relatively stable at 31 volts, just under the maximum voltage, until pilots detected a strange smell in the cockpit about 15 minutes after takeoff. The data showed a sudden, unexplained drop in the battery’s voltage after that, Mr. Goto said.
    “There is no direct evidence of overcharging,” Mr. Goto said, though he stressed it was too early to reach a firm conclusion, given the complexity of the electrical systems aboard the 787. “There is a possibility that something went wrong within the battery itself.”

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    • The U.S. National Transportation Safety Board said earlier this week that the JAL 787's battery "did not exceed its designed voltage." One of the Japanese investigators looking into the ANA Dreamliner incident said last week that the burn marks on the charred battery suggested overcharging, as among the more likely causes initially leading to the impression that the U.S. and Japanese probes were headed in different directions. Data from the aircraft's digital flight data recorder wasn't available at the time.
      The twists and turns of the U.S. and Japan probes—run separately but with the cooperation of the other—underscore the difficulty of troubleshooting the advanced electrical system that powers Boeing's flagship jet, celebrated at its launch for its revolutionary features. Among them is the Dreamliner's heavy reliance on electrical systems to perform many functions that were previously handled mechanically. The plane, for instance, moves parts of wings electrically instead of with hydraulic devices.
      Two engineers from Thales SA HO.FR -1.68%of France joined the investigative team in Japan on Tuesday, transport ministry officials said Wednesday. Thales designs and makes electrical systems for the aerospace and transport industries—including the battery-operation system for the Boeing 787. Engineers with GS Yuasa Corp., 6674.TO 0.00%the maker of the 787's lithium-ion batteries, are also involved of the investigation.

      The U.S. Federal Aviation Administration and other global aviation regulators last week grounded all Dreamliners until regulators are convinced the battery systems are safe.
      The data found on the digital flight data recorder of the ANA Dreamliner showed that the output voltage of the battery didn't exceed the maximum 32 volts, said Mr. Goto of the JTSB on Wednesday. It had stayed at 31 volts before suddenly dropping and then moving up and down, indicating that overcharging may not have been the cause of the incident.
      But JTSB officials cautioned that there is still insufficient data to rule out any potential causes of the incident entirely, since it is still unclear whether the voltage fluctuations were a cause or symptom of the problems.
      One unknown is whether there was excess voltage coming into the battery, said Mr. Goto. The data showed only the voltage of the battery output, not inflow of electricity into the battery, he said.
      The JTSB will also have to investigate the battery charger to figure out whether there may have been overcharging from the charger, Masahiro Kudo, a director general of the JTSB told reporters after the news conference.
      The flight data also suggested that the battery wasn't used during the flight. Instead, power was supplied by four generators connected to the engines. The voltage level remained stable throughout the flight until the alarms went off.
      Mr. Goto said the next step of the investigation will be to figure out why the voltage suddenly dropped.

      • 1 Reply to falmouthharbor
      • The 787 battery is similar to a laptop battery. A few years ago, Dell had a few laptops smoking in the laps of users. But eventually, the problem was solved. Most modern laptops use Li ion due to energy density and weight.

        The early data says the battery was not overcharged. This lets the charging system off the hook. But how come the battery smoked? These batteries have internal cooling . Something caused these batteries to self disintegrate. This is similar to D cells that leak their contents.

        The Li ion battery works for laptops and other mobile devices. It will work for the 787.

 
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