"COLIN LAMB" wrote in message
ink.net...
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

It's not unusual for any battery chemistry to show a higher voltage when a
discharged cell is tested against a high impedance DVM. That's why all
battery testers check a cell against a load.

Based on interpolation of the Energizer 9V Lithium 5mA discharge data curve,
it appears that the 6 .5V warning flash will begin somewhere after 230 hours
in service and the cutoff at 5V will occur 20 hours later. MH states that
you should expect only 4 hours of alkaline battery life after the low
battery warning flashes start. This strongly suggests that you should
expect 5 times the battery life with a lithium 9V after the warning.

That's not a particularly steep discharge curve. It actually should be
better since MH states that the mean draw of the EDS is 3.5 mA and the
Energizer discharge data is for 5mA draw.

See: http://data.energizer.com/PDFs/l522.pdf

I think I can live with that. I'll be using a lithium 9V and replace it at
the beginning of each season.

Bill Daniels