Lithium plating is an obstacle for the development of fast-charge batteries and enabling of widescale electric vehicle adoption. Synchrotron high-energy X-ray diffraction was used to directly identify and track lithium plating in a full LiNi0.5Mn0.3Co0.2O2 / graphite pouch cell operated with a 6C charge rate for greater than 1200 cycles. The magnitude and spatial distribution of lithium plating, lithium stripping, and the effect of plating on lithium intercalation into graphite were quantified. For discharged cell maps, irreversible and fully lithiated graphite (LiC6) was closely correlated with lithium plating and can be considered a highly reliable indicator of lithium plating in cases where plated lithium is below the detection sensitivity. Isolated regions of slight plating initially stripped to below the detection limit, but over time the coverage and amount of plated lithium increased while the stripping efficiency decreased. Long term monitoring of lithium formation in a fast-charge battery provides important information for a better understanding of lithium plating and stripping mechanisms in practical cells.