Mountain High EDS O2 system battery

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

From my personal observation at FL235 and the temperature minus 26C the unit
slowed down and then failed I put the EDS onto emergency supply.

Note the steep descent after this moment LOL
http://www.mals.net/bunyan04/pages/Picture%20001.htm

In future if I go above FL180 I will have a spare battery and a battery
inside my clothing (32C degrees is about optimum battery operation body temp
is 36C) with wires and connectors coming out to connect to the EDS unit.

I will also carry a spare or emergency oxygen system.

As simply having the battery in the pocket of the glider exposes the battery
to the cold temperatures so its just as useless.

Think of another thing its freezing cold you take your hands out of the
gloves you then have to fumble with the battery and fly the glider.

Remember if you smoke at ground level you are already at 5000FT

The hypoxia curve is worth a study as well.

Is adrenalin part of the discharge curve LOL

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 -

"In future if I go above FL180 I will have a spare battery and a
battery
inside my clothing (32C degrees is about optimum battery operation body
temp
is 36C) with wires and connectors coming out to connect to the EDS
unit.
I will also carry a spare or emergency oxygen system.
As simply having the battery in the pocket of the glider exposes the
battery
to the cold temperatures so its just as useless.
Think of another thing its freezing cold you take your hands out of the

gloves you then have to fumble with the battery and fly the glider."

Point(s) well made.

So far my O2 experience has been up to FL180. Certainly going far above
that brings forth other serious considerations. I have thought I would
install a continuous flow system as a back-up to the EDS if, and when I
decide to fly at those altitudes. Then also a spare/emergency?

Do you have any special considerations for the glider primary batteries
when it gets that cold?

"Go" wrote in message
oups.com...
So far my O2 experience has been up to FL180. Certainly going far above
that brings forth other serious considerations. I have thought I would
install a continuous flow system as a back-up to the EDS if, and when I
decide to fly at those altitudes. Then also a spare/emergency?

Do you have any special considerations for the glider primary batteries
when it gets that cold?


I think it depends on how long exposed as well as how cold. The ship's
lead-acid batteries have a fair amount of mass, so internal temperatures
will drop more slowly than some other stuff in the glider. Obviously,
battery location plays a role too, i.e. it's typically warmer in the cockpit
than elsewhere. Since the batteries are discharging and have some internal
resistance, the internal power dissipation also adds warmth. That said,
battery capacity at freezing will be down some 20% or more, and at -22F,
down 50%.

I understand Stemme insulated their battery installation for the wave
flights in S. America several years ago.

bumper
ZZ Minden, NV

Yes the glider batteries were packed by some pilots in foam etc.

I have also pack the baggage compartment with a spare fleece or two less air
mass to cool down and it insulates the area as well.


"bumper" wrote in message
...

"Go" wrote in message
oups.com...
So far my O2 experience has been up to FL180. Certainly going far above
that brings forth other serious considerations. I have thought I would
install a continuous flow system as a back-up to the EDS if, and when I
decide to fly at those altitudes. Then also a spare/emergency?

Do you have any special considerations for the glider primary batteries
when it gets that cold?


I think it depends on how long exposed as well as how cold. The ship's
lead-acid batteries have a fair amount of mass, so internal temperatures
will drop more slowly than some other stuff in the glider. Obviously,
battery location plays a role too, i.e. it's typically warmer in the
cockpit than elsewhere. Since the batteries are discharging and have some
internal resistance, the internal power dissipation also adds warmth. That
said, battery capacity at freezing will be down some 20% or more, and
at -22F, down 50%.

I understand Stemme insulated their battery installation for the wave
flights in S. America several years ago.

bumper
ZZ Minden, NV