Hi,
HazelNuts39:
...just like there are three wires for each voltage.
Yes, may be. The designers (of the battery) clearly assumed temperature of the cells would not be a problem. "Brief" APU use, MAIN batt. use only in emergencies (remember for the first time in an airliner MAIN battery was put COMPLETELY out of the bus) and light use on ground (not so frequent use when not AC present, and towing)
So, the "patented algorithms" comes always to my mind.
. i remember many years ago when working and living in a Skydive area i opened a li ion batt of a friend cameramen and found inside: Surprise! Electronics! I was shocked! All my k.I.S.S. principles came to my mind.
During all this days since Jan 7 i am designing a SAFEST (commercially speaking viable solution) and my charger WILL NOT USE ANY SOFTWARE for the critical cell charging. Just hardware (OBVIOUSLY REDUNDANT AND PROTECTED)
IMO algorithms should be made for help: Safety, etc. When relying on it for critical tasks you must have all means to FIRE them IMMEDIATELY when necessary.
The use of algorithms to optimize a DANGEROUS battery with ANY MECHANICAL PROTECTION against positive feedbacks (the so called here, thermal runaway) is :
I would like to analyze at least the schematic diagram of the harness on top of the cells in order to imagine what my colleagues had in their mind. Very probably they put redundancy on "balancing and sensing" wiring.
Certainly thermal aspects were not adequately managed. Temperature measurements, even in three different locations would not help too much. As it seems could be the case. Remember that:
In BOS AND ALSO in TAK the batteries were not supplying energy. (only if something like a diode module (TAK) or short circuit (BOS) but this possibilities seem were discarded by JTSB and NTSB.
Even a relay/contactor failure would not be sufficient for TAK case.
On redundancy i can sadly comment: We are observing redundant errors.
And the problems seems to come from "higher hierarchies" than just engineering/technical level.