For simplicity:-
The voltage of a cell is dependent on the technology(Chemistry) employed
the storage-capacity is a product of plate(electrode) surface -area within that cell.
The discharge-rate is a product of the technilogy and configuration of that cell.
Where Automotive LA batteries are concerned, there are standardised cases and terminals (shape and position)
Within the cases there is potential for a few thick plates, or a lot of thin ones. the more plates, the bigger the surface-area and the greater the peak-current potential. irrespective of how many plates there are, within a cell, all the pos. plates are bonded together like the fingers of a hand. the opposite polarity are linked likewise interleaved between them with porous spacers between,-this allows current to flow between ajacent Pos-Neg. plates, whilst stopping warping/shedding from mechanically shorting the plates together. that's why you get different prices, weights and energy-ratings in what looks like the "same" battery.-
The net result is 2 plates/electrodes. in a compact space.
-in the case of a cylindrical cell a "sandwich" of long strip plates and insulator-spacers is wound exactly like a Swiss-Roll (a capacitor is mechanically very similar!) compact, but doesn't use square spaces efficiently.
Back on topic... Lithium Technology has the potential to store a lot more energy in a smaller, lighter package , than Nickel Cadmium or Nickel Metal Hydride...in turn , these have superior weight and energy-density to Lead-Acid
The major disadvantage of Lithium technology ,is it's intolerance to deep discharge and maximum -capacity charge.
Keep within those boundaries and you can make massive short term current demands and have low self-discharge rates (virtually ALL batteries will go" flat" if left to their own devices).- which is why it seems eminently sensible that the "screamliner" constantly monitors and conditions it's batteries....or is that "Should constantly".... If it had done, there would have been no need to swap-out so many as if they were "use and throw" torch-batteries.
IMO , the Yuasa cells are beyond reproach... the charging/monitoring interface between cells and the aircraft's wiring-harness is the trouble-spot.
The state of the main/apu/rat power-deliveries is immaterial...a properly specified and built interface should ensure the battery is charged/discharged within it's safe working envelope.
Test-flights "may" uncover a shortcoming, but I'd bet a pound to a pinch of sh1t that the problem lies in the charger-unit.
I suspect also that the internal battery controllers are intentionaly configured to make the unit unusable by the end -user in"tailored" failure-mode thus ensuring a steady replacement and "reconditioning" market........
HOW MANY REPLACED, AGAIN ? Someone's taking the p155 and damaging the cost-savings potential.......biting the hand that feeds..../ killing the goose..... ??
Last edited by cockney steve; 6th Feb 2013 at 13:11.
Reason: tidy up some ambiguities/ omissions