Can it be calculated from cell voltage and mass, or is it manufacturer specified?
When an older (not the new lower voltage Fe type) Li-Ion cell reaches its max 4.2V then it is not yet fully charged and is still charging until the charging current drops to a fairly low current, then the charger should detect the drop in current and shut off.I think May be I am wrong but Li-Ion batteries commonly require a constant current, constant voltage (CCCV) type of charging algorithm. In other words, a Li-Ion battery should be charged at a set current level (typically from 1 to 1.5 amperes) until it reaches its final voltage.