ANA 787 makes emergency landing due 'battery fire warning'
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Wires to Monitor cell voltage
that's why all the lose wires, but they can just as easly cause a problem as prevent one. On a battery system I'm working on all the monitor wires are sleved to help keep them as part of the solution vs a new problem.
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Not so with LiFePo4
you can run them at 3.2v cell charge or discharge very flat. Pb are the worst they wont put out much unless you take them well under 2v cell and need 2.25v cell to at take a decent charge
OT, Thanks
That explains it very wel and had often wondered they solved the problems
involved.
As for the IGBT's, aggreed. I still have a copy somewhere of the GE Thyristor
Manual, which has an example of an ac in, ac out cycloconverter. A lot of thyristors,
each with it's own trigger circuit and commutation. Ground breaking devices in their
day, but later devices are so much more conveneient, if not quite so rugged :-)...
involved.
As for the IGBT's, aggreed. I still have a copy somewhere of the GE Thyristor
Manual, which has an example of an ac in, ac out cycloconverter. A lot of thyristors,
each with it's own trigger circuit and commutation. Ground breaking devices in their
day, but later devices are so much more conveneient, if not quite so rugged :-)...
harpf:
The monitor wires could cause a short if the insulation failed, but there's no evidence of this
from the pics and the monitor harness looks intact.
They probably use glass braid insulated wire, or similar, to prevent this...
that's why all the lose wires, but they can just as easly cause a problem as prevent one. On a battery system I'm working on all the monitor wires are sleved to help keep them as part of the solution vs a new problem.
from the pics and the monitor harness looks intact.
They probably use glass braid insulated wire, or similar, to prevent this...
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ANA had history of 787 battery problems
According to this report there was a history of battery issues with ANA 787s.
http://www.nytimes.com/2013/01/30/bu...anted=all&_r=0
As 5 of the 10 batteries replaced were changed because they had become discharged, maybe this should now be considered a safety issue, as charging from a low state of charge seems to be as risky as overcharging. If the regulators had been given a heads up about the number of battery replacements ANA had carried out, would things have been different?
And did any of the other 787 operators experience similar problems and how much did Boeing know about this?
http://www.nytimes.com/2013/01/30/bu...anted=all&_r=0
The airline said it told Boeing of the replacements as they occurred but was not required to report them to safety regulators because they were not considered a safety issue and no flights were canceled or delayed.
And did any of the other 787 operators experience similar problems and how much did Boeing know about this?
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In answer to my own question above, 'yes, there were battery problems with other operators' and 'yes Boeing did know about it'.
At least 100 batteries failed on 787 fleet | Business & Technology | The Seattle Times
According to that article the majority of the batteries were returned because they had gone so low that a low-voltage cutout was activated.
This sounds more and more like a charging/monitoring problem. Lithium-Ion batteries have a shelf life of two to three years so none of these batteries should have been anywhere near 'low voltage cutout' under normal operating conditions.
It would be interesting to know whether it was a random spread of batteries from 'aft' and 'main' that were returned, or whether the batteries that 'went low' mainly came from one area or the other? That information would help a lot in the diagnosis of this problem as each battery sits in a different electrical system.
At least 100 batteries failed on 787 fleet | Business & Technology | The Seattle Times
“We have had at least 100, possibly approaching 150, bad batteries so far,” the person said. “It’s common.”
This sounds more and more like a charging/monitoring problem. Lithium-Ion batteries have a shelf life of two to three years so none of these batteries should have been anywhere near 'low voltage cutout' under normal operating conditions.
It would be interesting to know whether it was a random spread of batteries from 'aft' and 'main' that were returned, or whether the batteries that 'went low' mainly came from one area or the other? That information would help a lot in the diagnosis of this problem as each battery sits in a different electrical system.
