Mountain High EDS O2 system battery

I have an EDS on order and have been reading the manual available from their
web site. It says "USE 9V ALKALINE BATTERY ONLY" in caps for emphasis.
They then go on to say that you can also use and external battery of any
type you choose.

OK, so what would be wrong with using a 9V lithium smoke detector battery
that lasts 5 times longer than an alkaline? I use one of these as a backup
on my Borgelt B40 and I've never had to replace it.

Yep, I'm gonna ask Mountain High too.

Bill Daniels

Bill Daniels wrote:
OK, so what would be wrong with using a 9V lithium smoke detector battery
that lasts 5 times longer than an alkaline? I use one of these as a backup
on my Borgelt B40 and I've never had to replace it.

The EDS likely has an internal power supervisor which is monitoring the
battery voltage, and triggers an alarm when the amount of remaining run
time drops below a threshold. The discharge profile for lithium
batteries is different from alkaline, the alarm may be triggered too
early, or too late...

Marc

"Marc Ramsey" wrote in message
om...
Bill Daniels wrote:
OK, so what would be wrong with using a 9V lithium smoke detector
battery
that lasts 5 times longer than an alkaline? I use one of these as a
backup
on my Borgelt B40 and I've never had to replace it.

The EDS likely has an internal power supervisor which is monitoring the
battery voltage, and triggers an alarm when the amount of remaining run
time drops below a threshold. The discharge profile for lithium
batteries is different from alkaline, the alarm may be triggered too
early, or too late...

Marc

Good observation. Here's a bit of further research.

When I normalize and replot the discharge data as voltage vs. % life instead
of V vs. hours, the shape of the discharge curve of lithium seems to be
identical to alkaline.
__________________________________________________ __________________________
_
Mountain High says this about the Low Battery Warning:

The EDS model D-1 unit continuously monitors the condition of the battery
during operation. The unit flashes the red LED once every two seconds to
warn that the battery has dropped to about 6 volts. The unit will, however,
continue to operate properly for about four (4) hours @ 25° C after the
indicator starts to flash. It will flash the red LED once per second to warn
that the battery has dropped to about 5
volts and should then be replaced ASAP. The EDS model D1 will operate for 60
to 80 hours with a fresh alkaline battery under normal operation. However,
because a very small amount of current (»1 µa.) is drawn by the unit while
turned off, the battery life is about 4 to 6 months. Therefore, during long
term storage the battery should be removed. Once the battery drops below 5
volts the unit will stop
operating and the red LED will remain on.
__________________________________________________ __________________________
__

Of course this suggests the low-voltage warning will come on with 4 - 5
times as much life remaining in a lithium 9V but that's not necessarily a
bad thing. If the warning came on one hour after launching for a 1000k
attempt, I might feel comfortable continuing the flight with lithium but not
with alkaline.

The above EDS alkaline battery life data is not especially comforting. A 4
hour margin after the low battery warning could cut short a long flight.
(If you even noticed the blinking red LED) If the alkaline battery is cold,
the margin could be even less. Lithium batteries are advertised to have
greater cold performance compared to alkaline.

At $6 for a lithium 9V vs. $2.50 for alkaline, lithium seems to be a really
good buy for any device that uses a standard 9V battery. The EDS manual
warns to be very careful with the battery wires when changing the battery so
doing so less often seems like a good idea too.

As for the idea that lithium batteries catch fire; if that were true, it
would be absurd in the extreme to use one in a smoke detector, yet that's
both the government and industry recommendation. The manufacturer's data
says that in the case of a dead short the battery will not exceed 90C. I
assume these 9V lithium's are not especially prone to catch fire.

Bill Daniels

Bill Daniels wrote:

__________________________________________________ __________________________
_
Mountain High says this about the Low Battery Warning:

The EDS model D-1 unit continuously monitors the condition of the battery
during operation. The unit flashes the red LED once every two seconds to
warn that the battery has dropped to about 6 volts. The unit will, however,
continue to operate properly for about four (4) hours @ 25° C after the
indicator starts to flash. It will flash the red LED once per second to warn
that the battery has dropped to about 5
volts and should then be replaced ASAP. The EDS model D1 will operate for 60
to 80 hours with a fresh alkaline battery under normal operation. However,
because a very small amount of current (»1 µa.) is drawn by the unit while
turned off, the battery life is about 4 to 6 months. Therefore, during long
term storage the battery should be removed. Once the battery drops below 5
volts the unit will stop
operating and the red LED will remain on.
__________________________________________________ __________________________
__

Of course this suggests the low-voltage warning will come on with 4 - 5
times as much life remaining in a lithium 9V but that's not necessarily a
bad thing. If the warning came on one hour after launching for a 1000k
attempt, I might feel comfortable continuing the flight with lithium but not
with alkaline.

My older model EDS has a battery test switch: steady light and sound,
battery OK; pulsing light and sound, only a few hours of life left. How
about the D1? If you test it as part of the pre-flight, you'll be able
to do that 1000K!


The above EDS alkaline battery life data is not especially comforting. A 4
hour margin after the low battery warning could cut short a long flight.
(If you even noticed the blinking red LED)

I check it when I check the oxygen level (most of the time).

If the alkaline battery is cold,
the margin could be even less. Lithium batteries are advertised to have
greater cold performance compared to alkaline.

At $6 for a lithium 9V vs. $2.50 for alkaline,

You are paying too much for your 9 V alkalines - they are half that at
places like Costco. Haven't seen the lithium units there, unfortunately.

lithium seems to be a really
good buy for any device that uses a standard 9V battery.

Until you forget to turn off the EDS, and a week or so later, it's dead.
A good thing for smoke detectors, for sure.

I use two alkaline batteries in my glider: one is in the EDS and serves
as the backup battery; the other (the primary battery) is velcroed to
the side of the unit and is plugged into the external power socket of
the EDS. If the primary, externally mounted battery dies, I just pull
the plug out of the EDS, and it switches to it's fresh internal battery.
It's an idea I got from Pat Martin.

--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

Bill,
a standard alkaline lasts me about one year.
I have a hard time remembering to replace it annually... 5 years is
too long....
Bela

I have used the EDS for five years now and only replace the battery
every season with a lot of (sorry I have no specific number of hours
operation to relate) flying above 12.5k' out here in the west.

I do keep a 9v battery with electrical tape over the contacts in my
little flight pouch in the cockpit. It is easy to replace in flight.

If it DOES lose power the default is to continuous flow. On one
occasion (this is why I carry a spare) this happened over the White
Mtns. and I actually regulated the airflow by squeezing the tube so as
not to run out of O2 on a fun day.

In my new ship I am connecting the EDS to main power, there is an
external power jack. But still keep a 9V in the unit (isolated) as a
back up. Total power loss, I still have O2 and a vario.

It seems to me this is a good plan. Any better ideas out there?

Go

Is there any documented discharge curve for these styles of batteries at
sub zero temps ? ....(eg) high altitude wave flight


--
keithw
------------------------------------------------------------------------
Posted via OziPilots Online [ http://www.OziPilotsOnline.com.au ]
- A website for Australian Pilots regardless of when, why, or what they fly -

"keithw" wrote in message
...

Is there any documented discharge curve for these styles of batteries at
sub zero temps ? ....(eg) high altitude wave flight

Take a look at:
http://www.ulbi.com/techsheets/UBI-3001_U9VL.pdf

Bill Daniels

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

"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