The charger manufacturer got a patent
Patent US5780994 - Detection of inflection point in secondary-battery charging process, which they claim as per
Innovative Inverter Technologies and Main Ship Battery Chargers for Power Conversion to apply with the 787 charger. Last sentence from the abstract: Accordingly, the voltage response is no longer monitored and the time remaining to reach the inflection point is used to complete the fast-charge operation. _If_ they really charge like that, without the monitoring the cell voltage, the problems seen are to be expected, as even a minor mismatch (caused amongst others by aging) of the assumed inflection point to the actual cell would lead to overcharge. Lithium cells will degrade fast with minor (trickle) overcharge and absolutely will not not tolerate any overcharge at fast-charge current. NiCd and Pb cells would be much more tolerant.