Hi,
FullWings:
If the batteries in question were installed so that they could be isolated,
This comment triggered an idea will post on a Fault tolerant battery. Less risk of "uncontained thermal runaway" and capable to be "isolated". Will comment on that later.
No pilot that I know would be happy with a piece of equipment in an inaccessible area that was a demonstrated fire risk, "contained" or not. What's the point of all the dangerous goods legislation if you carry something similar to a prohibited item around with you all the time?
saptzae:
32.2V is end of charge voltage (4.025 x 8). 29.7V is rated voltage.
I'd go for 25V being available when battery low and at a high current load.
Perfect.
I estimate that BDM drops less than 1V (0.8V typ) at 150A if based on Schottky diodes and less than 0.5V (0.3V typ) if based on MOSFets.
Some days ago i read and saved a .pdf from Sandia Labs telling on a device for 787 program. IIRC MOSFet. Itīs lost in one HD
My best bet, as outlined in earlier posts, Primary failure (short) due to gradual cell deterioration after one or more (in no particular order of preference) of :
Mismanagement by BMS.
Mishandling (assembly, rework, repair, maintenance, storage)
Mishandling deep discharge and reset BMU lockout
Mishandling external over voltage, such as bus over voltage, also during maintenance or storage (recharging - dunno they do that).
Tested to overstress - Boeing says they test a lot and hard (unlikely IMHO)
Bad cells (unlikely IMHO)
Fully agree including sequence (hierarchy)
Apparently, current battery tests do not detect cell deterioration. I do not claim that tests possibly could detect it.
Thatīs another concern i have with these cells. Lack of knowledge. "uncharted waters"
bill good:
Redesign - remove all batteries & use super capacitors. End of story!!
Yes, end of history: payload of the redesigned plane will be zero.
saptzae:
can make fireworks too, NiCad included.
no-hoper:
...verify on the ELECTRICAL maintenance page 1
that the APU battery voltage is 31 DC-V or greater"
This is an interesting indication. Conservative approach. Tight tolerance on batt. charge condition. Pre flight
Makes me remember the laptops battery range (empty to full of just one Volts)