Nominal voltage alkalines: ~1.5V
Nominal voltage NiMH: ~1.2V
The "nominal" voltage of a battery is exactly what the word says, the "named voltage" printed on the side. Dictionary definition: "nominal" = "in name only". A nominal value is not the same as the actual value.
Words have many meanings. The definition I used here is Merriam Webster 3B (see attachment); relating to theoretical size, or approximate, which is what is typically used in engineering. In my example above I used the symbol for approximate (~), which seems to fit this definition and situation. The actual alkaline voltage can range from ~1.6V down to 0.8V (or 0.0V
).
In this case, "nominal" meaning "named voltage", or "theoretical voltage" seem to be both right, even though the battery voltage can vary greatly. Not a big deal.
What surprised me recently is that the Energizer Ultimate Lithium L91 battery spec says it has a nominal voltage of 1.5 Volts, but the application manual says the voltage can range from 1.74V to 1.83V. (I learned this from this thread.
)
This caused a problem for me recently. I have several wireless thermometers and weather stations. The manuals warns against using lithium batteries because they have "to much power" (bad description from the manual writer). This didn't make any sense to me because the thermometers have very low power consumption. The thermometers worked good with the lithium batteries, until recently when I got a new thermometer that would not work with lithium batteries, but worked with alkaline batteries. The higher voltage of the lithiums (1.8V) is too high for the circuitry in that thermometer.