When upgrading a PWRcell system by adding more battery modules, a module spacer kit helps maintain proper spacing and air flow. The kit contains a spacer and associated hardware. Module spacer kits are only required for PWRcell systems with an odd number of battery modules (i.e. 3 or 5 battery modules). Specifically, PWRcell 9 and PWRcell 15 battery configurations would require a spacer kit, but PWRcell 12 and PWRcell 17 would not.