Hi,
Hi-Tech
This STRATEGICAL ERROR is going to cost Billions of dollars to Boeing. And we are talking of a MERE battery. A device with a VERY SIMPLE TRANSFER FUNCTION: You store energy (you charge it) and it give you back the energy (after losing some % in the process). Is ABSOLUTELY DANGEROUS (IN ALL ASPECTS) to have only one option.
Clever design and config.
Last night i did look the data sheet of the SiC modules 787 uses as switches (one that may explain the "miswiring" reported). Sandia
AFAIK funded by US taxpayers made an R&D for these devices used also in F35. Even this modules has competitors. (i will send you the data sheet by email. I lost the internet link but downloaded the .pdf) and are costly. (thousands dollars) Are "simple" switches. Seems the R&D of 787 suffered many difficulties (many delays, etc.) and they put the plane in commercial operation assuming risks (certainly estimated) and now they are completing the R&D by the hard way (field retrofit).
The config you mentioned in EADS planes certainly is more "flexible" due two things:
1) You mentioned
2) Requires less electricity from batteries
In 787 the required redundancy (did you see the
newairplane site?) required the "150 Amps" and the weight optimization probably was the decision making big factor. (together the pressure on Boeing to use the NEW WONDERFUL cells)
But the use of just one BAD battery (MAIN) was a serious TECHNICAL AND ORGANIZATIONAL error. It would be too risky and Boeing is receiving the bill.
Why Boeing is not thinking of splitting the battery into 3 or 4 units? That way the heat build up and the danger to the air-frame is minimal.
Did you see my
first and
second version of a possible (quick) fix:
2 similar batteries in parallel (same cells better separation, larger case)
Both PCB´s in separate chamber
Same (revised) BMS
Same charger (One for both batteries, "switched")
Improved sensing to shut off (battery) when one cell "starts" to fail
1 BDM per battery (MAIN)
Sturdier and vented (to outside) case.
Located nearby current positions (cable lenght optimization)
Total 4 batteries (2 MAIN, 2 APU)
Result: Better dependability, fault tolerant, graceful degradation, less fire risk, planes flying sooner (probable) and safer also because (batteries) could be derated.
Weight penalty: Aprox. "1 pax"
I know this will be time critical for certification etc.
The mentioned posted approach could be expedite
Think about it, instead of trying to create a meteor shower in the sky with a burning LI battery.
Problem is much more serious than just a battery burning. An "electric" plane (we can say that on the 787) made using flammable parts is a new issue.
I did study EMI/EMC (ESD, grounding, etc.) and always think on issues in non metallic planes. The extensive use of solid state switching devices is another concern.
To be continued by editing.