Two things that are interesting about checking the OCV (Open Circuit Voltage) on LiFeS2 (lithium primary cells):
1. A cell with an OCV less than 1.70 volts is dead. (A good cell will have an OCV greater than 1.74 volts. New cells are usually 1.79 to 1.83 volts.)
2. If a cell has been used, the OCV slowly rises after it is taken out of a circuit. If you measure anything less than 1.74 volts, wait a while and measure again. When the voltage stops changing, that's the value that reflects the actual cell condition.
There is plenty of interesting reading in the Energizer Lithium Iron Disulfide Handbook and Application Manual. An excerpt:
"Although the higher OCV of the LiFeS2 system is 1.8 volts, the nominal or rated voltage is 1.5 volts which makes it a suitable replacement for alkaline and nickel systems. The battery voltage will drop when it is placed under load. For this reason, the higher OCV will typically not damage electronic components, but device designers should take into consideration that the OCV of fresh batteries can range from 1.79 to 1.83V. LiFeS2 batteries fully meet the ANSI specification for a 1.5V battery. When a drain has been applied to the battery, the OCV drops dramatically and then slowly recovers with time. The OCV for a battery can be misleading. A "good" battery will generally have an OCV >1.74 volts. Any battery with an OCV <1.70 (after it has been allowed to recover) is completely discharged. Although an alkaline battery may read "good" at 1.6 volts, this reading on a LiFeS2 battery indicates the product has been discharged."
Also see Monty Python and the Holy Grail: "I'm not dead."