Retention frame for a battery pack

A battery pack comprising:

• a plurality of batteries stacked in layers one atop the other;
• a base supporting said plurality of batteries;
• a plurality of spacers disposed above and below each layer of batteries for holding said batteries and providing air passages around said batteries to allow air flow around said batteries;
• and
• a retention frame affixing said batteries to said base to restrict movement of said batteries, said retention frame including a plurality of beams interconnected and extending along ends of said batteries and applying a vertical force against said batteries to hold down said batteries;
• wherein each spacer is divided into sections, each section having two end walls, two side walls and horizontally disposed upper and lower edge portions extending around the inner perimeters of said sections, wherein bottom edges of the batteries are seated against the upper edge portions when the spacers are located beneath the batteries and the lower edge portions are seated against top edges of the batteries when the spacers are located above the batteries, and a sheet of material is disposed above each spacer that is located above the batteries to define the air passages above and below the batteries.