Based upon my experience, lithium batteries has a steeper voltage decrease
curve when the voltage does start to decline than alkaline.

If that is the case, then once the voltage decreased to the voltage required
to set off the low voltage warning, it may have much less time until it is
no longer usable than a standard alkaline battery.

Thus, the warning time may be less for a lithium battery than the alkaline.

Also, I have learned another lesson about lithium batteries. I was
servicing a piece of battery operated equipment. It was off and I checked
the lithium battery and it measured about 9 volts. I then proceeded to
waste a half hour looking for other problems and decided to install another
battery. Presto, it worked fine. Then I noted that a depleted lithium
battery will measure almost full voltage when there is no load. Under a
slight load, it dropped down to 3 volts.

Alkalines are very good about measuring voltage, even without a load.

Always measure the voltage of the lithium battery under the intended load.

Colin N12HS