An AMB supported, 140 kW energy storage flywheel has been developed to provide 15 seconds of ride-through power and UPS service in conjunction with a diesel generator set. The flywheel, which operates in a vacuum, is supported by AMBs to minimize bearing losses, and has a high power motor/generator coupled to an efficient power conversion module. Beta units are scheduled to be released to six customer sites in July of 2005. The flywheel has been updated incrementally from an earlier configuration that was reported in the literature. The changes are discussed here and include: 1) increased flywheel mass to allow full power delivery over a longer period of time with less speed differential, 2) replacement of the radial magnetic bearing with a three axis bearing that provides passive axial lift to support the increased rotor weight within the same magnetic bearing envelope, 3) a new backup bearing mount to improve the dynamic performance of the flywheel on the backup bearings, and 4) an AMB controller/amplifier has been selected which has long production history and is well suited to volume applications.