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787 Batteries and Chargers - Part 1

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787 Batteries and Chargers - Part 1

Old 11th Feb 2013, 20:16
  #641 (permalink)  
 
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bonjour mm43!

Diagnostics - Self test, Output voltage, Output current, Operating hours, Temperatures, Power.

Was the BC-1300 LithIon specific? From the literature, the LithIon pack, whether pouch, prism or roll, does not tolerate intrusion into its Cathode, Separator, Anode stack. Even the slightest foreign object will cause a focal "shutdown" and compromise the useful life.

I have no doubt there are diagnostics and storage. The Battery install, however, suggests the only wiring external to the case is +/- conductors, and Ground. Would the diagnostics storage be co-located with the PCBs? Inside the case?

many thanks
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Old 11th Feb 2013, 20:47
  #642 (permalink)  
 
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Two pictures i hadn´t seen published with side views of the cells

787 battery cell pictures

from this site

Last edited by RetiredF4; 11th Feb 2013 at 20:48.
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Old 11th Feb 2013, 21:06
  #643 (permalink)  
 
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White wad

There is only one wire going into the white wad which I suspect is connected to the intercell strap like the strap to its immediate right. Having a temperature sensitive device in series with this wire (if it is indeed the temperature sensor) would be illogical.
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Old 11th Feb 2013, 22:14
  #644 (permalink)  
 
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kilo It could easily be a pair, imho. The sensor would not be "connected" electrically to the strap, but affixed with adhesive. Check the image supplied by Retired F4? on the left, on top, you will see remnants of the "WhiteWad" undamaged by fire. my assumption is that it is 'fireproof' and could indeed be an insulator, cover for a temp sensor?

franzl...Those pics are from the NTSB page 7 "Thermal Damage" "page"?

This page shows the orientation incorrectly. the image on the left, has the "front" of the Battery on the left. That makes the side closest the "Right" side, not the left. The other image the same, reversed.

That is, if the orientation is observed from the "front" of the battery.

My conclusion is that the more severe damage, that on the 'right' side (the correct labelling), is also the side closest to the serious damage to the equipment in the bay to the right of the APU BATT situs. There was severe heat damage to the decking below the Battery as well. Fire damage was NOT limited to the interior of the Battery enclosure, and the fire damaged equipment outside the battery, something the Installation was required not to do, per the Lithium considerations in the FARs.

Is that the Sandilands' site?

Last edited by Lyman; 11th Feb 2013 at 23:06.
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Old 11th Feb 2013, 22:51
  #645 (permalink)  
 
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MM43:

Charger faults - Fan speed, CPU Temperature, Voltage, Current, Power, Stored fault history.
Battery faults - Abnormal temperature, Temperature sensor circuit, Cell unbalance sensor unit.
LED display - Eight-character alpha-numeric.
Diagnostics - Self test, Output voltage, Output current, Operating hours, Temperatures, Power.
Time - Date, Software revision.
Charge mode - Bulk charge mode, Topping charge mode, Trickle charge mode.

The likelihood of their flagship B787 charger providing less data than
above would IMHO be highly unlikely.

Ideally, yes, but the devil's in the detail. It doesn't say, for example, if
temperature is sensed for each cell, nor does it say what the sample frequency
is, ie: how often data is logged and under what conditions; singly on a
significant event, or continuously in the background, much as an fdr would
during flight.

Some systems log all the data at fixed intervals or sample rates, with each data
log entry timestamped, so that faults that develop over time can be traced back
by reviewing all the records. If the charger only logs a subset of available data,
or logs at too infrequent intervals, then it's quite possible that events that
lead up to a serious failure will be missed in the log. .

Supposing that the JTSB and NTSB examined the charger records straight up and
found nothing untoward except the battery fail event, then it would be reasonable
for them to dissect battery cells in order to deduce a reason for that failure.
Possibly, but it's also possible that there's not enough data being logged in the
first place for an accurate assessment...
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Old 11th Feb 2013, 23:02
  #646 (permalink)  
 
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kilomikedelta: agreed

A possible location for one or more temperature sensors is the transverse 'bar' that separates cells 2 and 7 from cells 3 and 6. There are some wires going down from that bar between cells 2 and 3 near the battery case. There are also 5 or 6 wires going to a connector that is vaguely visible below the connector that connects the left half of the cell voltage harness to the rear PCB:


Last edited by HazelNuts39; 12th Feb 2013 at 08:33. Reason: clarify cell numbering
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Old 11th Feb 2013, 23:41
  #647 (permalink)  
 
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HazelNuts39

It is cells 2,6 and 3,7 that are paired, transverse. According to the image above.

from RetiredF4's post

Last edited by Lyman; 11th Feb 2013 at 23:44.
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Old 12th Feb 2013, 00:25
  #648 (permalink)  
 
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Lyman, others...

The size of those wires, carrying that much amperage??? Really? Powering an aircraft??

What is to bet the charging system wiring is used to heat the main cabin

If the batteries are that sensitive to differences, would not the individual wire length be of concern?

I see the bus bars, but what are those connected to?

Boeing just whored (hired)a new person to source the battery/charging aux power assemblies.

Last edited by FlightPathOBN; 12th Feb 2013 at 00:27.
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Old 12th Feb 2013, 00:36
  #649 (permalink)  
 
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The conductors at the front of the battery case looked about 8 Gauge, braided Copper.
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Old 12th Feb 2013, 01:03
  #650 (permalink)  
 
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Cell numbering

Just so we're all singing from the same page in the hymn book: Cell #1 is closest to the printed circuit boards (front of case) on the left case side, cell #4 is at the the left back of the case, cell #5 is closest to the printed circuit boards in the right side of the case etc. Do we agree? The 37 monitor wires are just that. They only connect to the printed circuit boards. The output jack (J3) comprizes two ~1/4 inch diameter sockets good for ? 60 amperes for a reasonable distance. I don't see any monitor wires going between the cells below their tops.

Last edited by kilomikedelta; 12th Feb 2013 at 01:21.
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Old 12th Feb 2013, 01:04
  #651 (permalink)  
 
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Lyman - #641,
The Battery install, however, suggests the only wiring external to the case is +/- conductors, and Ground. Would the diagnostics storage be co-located with the PCBs? Inside the case?
To the contrary, the charger and the battery case are connected by a multiple pin cable, and the PCB's located in the battery compartment are probably concerned with buffering bi-directional data between the units.


The THALES charger above and a close-up of the J1 circular connector under examination by NTSB is below. The battery case has the complementary data connector above the battery terminal connectors.



This link will provide a large close-up of the front of the JAL battery case.

My guess is that THALES is the prime contractor and Securaplane is the sub-contractor providing the charger and BMS.

@ syseng68k

I suspect from what I see, that a great deal of data is being processed between the units.

Last edited by mm43; 12th Feb 2013 at 01:07.
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Old 12th Feb 2013, 01:20
  #652 (permalink)  
 
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kilo, did you spot the remnants of WhiteWad? Did you see my correction to the labelling on the Thermal Damage image? Right/Left transposed?

mm43. I did not see the pin coupler, the battery was too fried. Again, though, re: the BC-1300 monitor/ is it dedicated to LITHIUM Ion?

The sensing of temperature could certainly be done at the external cell casing, but I don't think any internal data could be had?
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Old 12th Feb 2013, 01:33
  #653 (permalink)  
 
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mm43 are you sure the link to the Battery close up is JAL? JAL had the cover plate and the conductors ripped off, by the FD.
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Old 12th Feb 2013, 03:49
  #654 (permalink)  
 
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One thing that I find interesting - shocking really - is that from the pictures of the intact battery, there appears to be no attempt to provide a thermal barrier between the individual cells. This would seem to virtually guarantee that if ones goes, they all go - kind of like storing eight Roman candles right next to each other. If there was some sort of thermal barrier that could limit heat spread while the shorted cell uses up its energy and burns itself out, perhaps the other cells would remain intact thus greatly lessening the total damage. In the old days, a metal/asbestos laminate often worked quite nicely, but I'm sure more modern materials are available.

Another interesting observation is that there appears to be no direct cell temperature monitoring (to be fair, it may not be visible from the top). All I can see is what appear to be thermistors attached to each of the jumper busses. The thermal lag time from this arrangement would make it essentially useless for detecting cell thermal abnormalities (but at leas the totally non-flammable copper buss will never overheat!). Even my lowly Makita Li-ion drill has a thermistor directly attached to the cell casings.
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Old 12th Feb 2013, 04:09
  #655 (permalink)  
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FlightPathOBN, Areobat, Lyman -- It appears the questions are coming full circle.

I suggest a re-read of the thread as several expert contributors have previously addressed these supposed new concerns.
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Old 12th Feb 2013, 05:40
  #656 (permalink)  
 
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@ Lyman,
I did not see the pin coupler, the battery was too fried. Again, though, re: the BC-1300 monitor/ is it dedicated to LITHIUM Ion?
The BC-1300 series are for both Ni-Cad and Securaplane Lithium-Ion batteries.

The Battery charger BMS 50 pin connector J1 is connected to its complementary J1 connector on the Battery pack case. This should be obvious when viewing this exemplar pack courtesy NTSB.

P.S. The original link I posted of the front of the damaged JAL battery pack, was just that, the one under investigation by the NTSB.

Last edited by mm43; 12th Feb 2013 at 05:46.
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Old 12th Feb 2013, 08:46
  #657 (permalink)  
 
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Originally Posted by kilomikedelta
I don't see any monitor wires going between the cells below their tops.
Look at the RH picture (Cells on the right side) in RF4's link.

As to cell numbering, I think the sequence of cells connected in series is more logical, i.e. #5 at the rear and #8 nearest to the PCB's at the front of the battery case.
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Old 12th Feb 2013, 09:14
  #658 (permalink)  
 
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Using temperature to shut down a battery (even with individual cell monitoring) will be closing the stable door after the battery has bolted!

The lag between a short which could cause a runaway event and the associated temperature increase makes it an ineffective protection. what a short would do however is cause a significant change in the individual cell voltage/current characteristics. This, with effective algorithms to control it would be the most effective way to determine imminent runaway and take the battery off line.

As for monitoring. On a modern aircraft there are systems in place which will tell you the status of a contactor! Of course maintenance would have checked the CMC interrogated the BMS and it would, in association with the FIM, have pointed to the components to replace.
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Old 12th Feb 2013, 09:35
  #659 (permalink)  
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Using temperature to shut down a battery (even with individual cell monitoring) will be closing the stable door after the battery has bolted!
That would depend what is causing the temperature rise, if it is just due to the start of overcharging then the sensor would shut down the charger before any damage is done. If it's due to a short in the battery cell I agree with you.
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Old 12th Feb 2013, 12:52
  #660 (permalink)  
 
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re- the 50-pin data connector....don't get carried away by this, they're standard stock items, and the incremental sizes may well mean that , for example, you have 31 wires but the connector increments are 30-pin or 50-pin (would give you 19 "spare" pins)

Were the individual sub-cells to beindividually controlled(even if only with a fusible-link) the battery would still be able to perform it's primary function-emergency power-albeit at slightly reduced capacity....isolating a whole cell , not only reduces the capacity,but the output voltage....not good!

As designed at present, that doesn't appear to be an option as the inter-cell straps are bolted directly to the cell-terminal with no alternative switching to bypass a faulty cell.

I stand by my opinions expressed before, re-design/interface/quality. of all but the GS-Yuasa products which I believe to be beyond reproach.
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