The battery Enclosure design from https://hackaday.io/project/20458-osug-open-source-underwater-glider was modified to house 12 18650 Lithium cells in a 3S4p configuration to power the glider.  The power pack also acts as a moving pitch weight to help the glider pitch down when diving and pitch up when surfacing. The original test of this unit showed it had too much friction between the batteries and the glider tube wall so some low friction blue tape was used. Changes in the design need to be implemented so that the power pack does not touch the glider walls, this will prevent unnecessary wear and power draw.

Here is a skeleton view of the pitch battery system.