We performed a battery of procedures in order to remove this 74.9-watt-hour array of lithium-polymer cells.

For the Late 2013 model, we got 71.8 Whr—so we're up a whole 4% capacity, for an extra 11% runtime. We're gonna chalk the rest of the boost up to the Broadwell architecture's efficiency gains.

The Dell XPS 13, however, manages an HD screen and an (alleged) 11 hours of run time on a 52 Wh battery.

This familiar Retina denizen, the Texas Instruments BQ20Z451 Gas Gauge IC, measures battery life.

This IC should be similar to the older BQ20Z45, or its replacement, the BQ20Z45-R1.