@TURIN
Obviously the only one in class who looked and absorbed
Baaaack in the early days of the thread, I stated that Li-Ion .Li Poly technology, though having very high energy-density, had significant operational drawbacks.
Safe , repeat charge-discharge cycles rely on a strict care-regime.
ALL cells in a pack MUST be balanced when charging.
ALL cells should only use the "middle-portion of their capacity....IE charging should be cut off at a critical value BEFORE maximum potential cell voltage
all cells should be only partially discharged, leaving a critical ,safe-voltage residual charge.
IF THIS REGIME IS FOLLOWED, very high rate discharges are available with very high reliability. The downside being reduced available capacity*
Spontaneous combustion is not unknown, but bear in mind, these are NOT 12,000 dollar packs, NO! they're less than 100, typically, and operated by amateur enthusiasts in public places and insurers are quite willing to offer affordable cover.
Back to the core argument, which was The battery has to be able to drain completely to self-destruction in order to maintain basic instruments and braking , in event of failure of all power-generation sources.
THAT'S where the BIG RED OVERRIDE BUTTON comes in.....just like the Cirrus parachute, it's always there, you should never need it, but in that highly improbable 5h1t or bust situation, it offers a "get out of jail " card to access the last portion of the stored power in the batteries (destroying their rechargeability in the process)...but that's little price to pay for a monitoring and protection system which maintains the batteries within their safe operating-envelope and stops "unskilled" personnell taking them outside those parameters (which is the alleged reason so many were "locked-out" and had to be field-changed- 150 units across a fleet of 50??)
* The reduced capacity, in turn, bought into question the marginal advantage of using this Vs. one of the lower energy-density but safer Li. technologies.
There now, that's saved a mammoth trawl through all the dross and diamonds , hasn't it?
