（A question on the number of spare batteries permitted in a shipment.）
This is a question on lithium batteries packed with equipment following Section II of Packing Instruction PI 966. The 58th Edition DGR for 2017 reads: “The number of cells or batteries in each package must not exceed the appropriate number for the equipment’s operations, plus two spares.”
If the unit must have a minimum of 4 batteries to operate, can 2 sets of spare batteries or a total of 8 batteries be permitted as “spare”? DGR shows ”two spares” and do not say “two sets”. Kindly give us your guidance. (30 Nov 16)
The interpretation of the term “two spares” by IATA is “two spare sets”. However, there is no electronic device which must have two or more batteries to operate. All electronic devices operate with one battery. So, the argument is meaningless. However with cells, there are electronic devices which needs multiple number of cells to operate. In that case, the “two spares” can be interpreted as “two spare sets”.