Does anyone know the voltage of a dead Energizer Advanced and/or Ultimate Lithium? And also what would be the resting voltage with ~20% charge remaining?
Lithium batteries are not like alkaline batteries, they do not have a neatly declining voltage. Their voltage remains rather steady until the end, where it suddenly drops off. A 95% depleted lithium battery will probably have 1.5 OCV (open circuit voltage or resting voltage). An 80% depleted lithium battery could be 1.6V open circuit. A 0% depleted battery will likely be 1.80V. Here is the Energizer application manual for the Ultimate Lithium chemistry: http://data.energizer.com/PDFs/lithiuml91l92_appman.pdf
My 2 EA92 measure 1.80V resting. Under a load on my meter’s battery tester (100 mA), both batteries measure 1.65V.
Open circuit voltage for Li-FeS2 chemistry is not a good way to determine remaining charge. The difference between 100% charge and 30% charge is probably 0.08V or thereabouts.