You want a battery pack that can deliver 16-18amps so either the KAN 1050 cells or even the HECELLs will provide good power and be relatively light.

In general, the newer NiMH cells can provide more capacity and more current for a given weight than do NiCd cells. The older generation NiMH cells had slightly less voltage and it was typical to add a cell for every 6 or 7 cells to equal a NiCd pack. Today, that is no longer the case.