a Li-Ion in a lead acid world.

On Nov 12, 9:29*pm, Mike the Strike wrote:
I remember fun days working in a lab where colleagues were developing
the "revolutionary" sodium sulfur battery (colloquially referred to as
the "fire and brimstone" battery). *The chief skill developers learned
was how to run fast while wearing asbestos suits and full-face
protective helmets. *If you've never had to deal with a bucket of
burning molten sodium, you've never lived! *(Hint - water isn't
terribly useful!) *You probably wouldn't want any quantity of burning
(molten or otherwise) lithium near you or in your glider either.

Lithium is WAY too close to the reactive end of the periodic table
(right up there with sodium, magnesium and potassium).

MIke

Mike,
I have no problem with considering Li-Ion's to be unsafe and to have
no place in a glider, but I don't understand having that opinion and
then flying with 1 to 3 of them. That was why I burned up an Ipaq
battery, to see if they are too small to cause a problem. My
conclusion is that anything from 800 mAH or larger, and probably
smaller, will make a glider uninhabitable.

But perhaps a better way of getting a handle on the risk is to look at
the incident rate, said to be about 100 cell phones fires between 2002
to 2004, out of more than 200 million cell phones are in use. This is
consistent with a fire risk of something like 1 in 4 million per year
of use for 'good' batteries and 1 in 200,000 for defective ones.

Laptop fires:
There were two recalls, the first of 9.7 million laptops after 16
fires, the other of under 6 million after 50 fires. This was for
defective units with metal particles that internally shorted out the
battery.

More info he
http://www.consumeraffairs.com/news0...#ixzz157SfeqzG

and he
http://www.buchmann.ca/article28-page1.asp

Really I am not trying to convince anyone that Li-Ions are safe, I
thought it would be helpful to have a discussion about them. The most
valuable fact for me was the existence of the 15AH lead acid unit.

Brian

On 11/13/2010 2:33 PM, brianDG303 wrote:

Mike,
I have no problem with considering Li-Ion's to be unsafe and to have
no place in a glider, but I don't understand having that opinion and
then flying with 1 to 3 of them. That was why I burned up an Ipaq
battery, to see if they are too small to cause a problem. My
conclusion is that anything from 800 mAH or larger, and probably
smaller, will make a glider uninhabitable.

But perhaps a better way of getting a handle on the risk is to look at
the incident rate, said to be about 100 cell phones fires between 2002
to 2004, out of more than 200 million cell phones are in use. This is
consistent with a fire risk of something like 1 in 4 million per year
of use for 'good' batteries and 1 in 200,000 for defective ones.

Laptop fires:
There were two recalls, the first of 9.7 million laptops after 16
fires, the other of under 6 million after 50 fires. This was for
defective units with metal particles that internally shorted out the
battery.

More info he
http://www.consumeraffairs.com/news0...#ixzz157SfeqzG

and he
http://www.buchmann.ca/article28-page1.asp

Really I am not trying to convince anyone that Li-Ions are safe, I
thought it would be helpful to have a discussion about them. The most
valuable fact for me was the existence of the 15AH lead acid unit.

I think there are some important differences between the Li-ion
batteries used in consumer products and those we are contemplating using
in our gliders:

* the cell phone, laptop, power tool batteries are high volume
production products. My guess is they are likely more consistent
in quality than buying hand assembled, small batch (or only
one-at-a-time) units.
* they all have dedicated, proprietary chargers that plug in to only
their intended battery
* they store much more energy than a laptop battery, and far more
than a cell phone battery, so even be a small problem is likely
turn in to a bigger problem than the cell phone/laptop battery.
* the high volumes make good engineering and testing of the designs
for the battery, it's protection circuitry, and it's charger
relatively cheap per unit
* they aren't subjected to the low pressures of 18K and higher that
many of us routinely achieve.

The high price will keep most pilots from buying one, so I'm not too
worried about imminent fireballs on the end of a tow rope. It does seem
prudent to consider Li-ion only if you really, really, need to save a
few pounds or increase the capacity a few amphours, then buy it from a
reputable supplier (not the cheapest), and pay strict attention to the
charging procedures.


--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarm http://tinyurl.com/yb3xywl
- "A Guide to Self-launching Sailplane Operation Mar/2004" Much of what you need to know tinyurl.com/yfs7tnz

When I found that my cell phone and my iPAQ had Li-Ion batteries that
were 1 to 3 times the 800 mAH size that Brian feels could “make a
glider uninhabitable”, I got motivated to look into what might cause a
problem with Li-Ion.

An EPA technical article said Li-Ion batteries were safe only if
they operated in a small range of voltage and temperature (cell
voltage between 2.0 to 4.2 volts, and cell temperature between 0 to
120 degrees C). Charging outside of this range causes most problems,
but high temperatures can cause thermal runaway spontaneously.
Underwriters Laboratories specifies Li-Ion battery tests that over-
charge, short circuit, puncture, and over heat - they want to see no
explosions or burning result. Shippers have to pack Li-Ion batteries
so they are protected from damage and short circuit, and if they’re in
a device it cannot accidentally turn on during shipment.

As the Buchmann article Brian referenced pointed out, Li-Ion
manufacturers try to achieve reliability by including safety
mechanisms within the cell, and by adding protection circuits within
the battery pack. But the protection circuits can be destroyed without
the user knowing, via static electricity or a faulty charger. Further,
internal defects can occur that might defeat the cell safety
mechanisms. The massive Dell/Apple battery recall was for Li-Ion
batteries made by Sony, whose batteries were contaminated internally
during manufacture with microscopic metal particles. It was possible
for the metal particles to trigger thermal runaway (also referred to
as “venting with flame”) that cannot be stopped once it starts.

For us glider pilots I conclude we’re probably OK as long as we don’t
fly with dropped or damaged cell phones and/or iPAQs. It would also be
a good idea to turn your cell phone turned of during flight.

But one big problem for us glider pilots is that we’re charging our
iPAQ’s Li-Ion cells while flying, and there’s a problem if repeated
charging occurs below 0 degrees C. Metallic lithium will plate the
inside of the cell, which causes the cell to be more vulnerable to
thermal runaway if it is subjected to impact, crushing or high rate
charging (like maybe if you run your iPAQ down and then connect it to
the ship’s power). For those of you who fly in real cold weather or
who fly at high alititudes, be aware.

-John

On Sun, 14 Nov 2010 08:04:47 -0800, jcarlyle wrote:

But one big problem for us glider pilots is that we’re charging our
iPAQ’s Li-Ion cells while flying, and there’s a problem if repeated
charging occurs below 0 degrees C. Metallic lithium will plate the
inside of the cell, which causes the cell to be more vulnerable to
thermal runaway if it is subjected to impact, crushing or high rate
charging (like maybe if you run your iPAQ down and then connect it to
the ship’s power). For those of you who fly in real cold weather or who
fly at high alititudes, be aware.

A very interesting description of what can cause a thermal runaway.
Thanks.

I use a Binatone PNA to run LK8000 and have a couple of questions:

- when a PNA or PDA is running normally, how warm is the internal
Li-ion battery, i.e. what are the limits on the battery staying
warm enough to keep it above zero?

- Is there any way of using these things that minimises the chances
of damaging the battery?

From what you say, running the PNA well down before plugging it to
charge it isn't so clever at low temperatures. I keep mine fully
charged when its out of the glider and its always connected to the
charger when I'm flying with it. Is this the best way of keeping the
battery warm and happy?


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

Martin, you're welcome.

I wish I could answer your first question, but I cannot. I suspect it
depends heavily on how insulating the PNA case is, how much current
the PNA draws, and how much heat the PNA's backlight and other
circuitry generates. You'll need to experiment to find out, I'm
afraid. And then you've still got some leeway, probably, because I
suspect that the lithium plating doesn't start immediately at 0C and
it will also depend on the charging current.

As for your second question, what you propose is exactly what I think
you should do. I keep my iPAQ on charge at home and also charge it in
my car until just before I put it in the cockpit, when the ship's
power takes over keeping the charge up.

-John

On Nov 14, 3:29 pm, Martin Gregorie
wrote:
A very interesting description of what can cause a thermal runaway.
Thanks.

I use a Binatone PNA to run LK8000 and have a couple of questions:

- when a PNA or PDA is running normally, how warm is the internal
Li-ion battery, i.e. what are the limits on the battery staying
warm enough to keep it above zero?

- Is there any way of using these things that minimises the chances
of damaging the battery?

From what you say, running the PNA well down before plugging it to
charge it isn't so clever at low temperatures. I keep mine fully
charged when its out of the glider and its always connected to the
charger when I'm flying with it. Is this the best way of keeping the
battery warm and happy?

On Sun, 14 Nov 2010 13:33:59 -0800, jcarlyle wrote:

I wish I could answer your first question, but I cannot. I suspect it
depends heavily on how insulating the PNA case is, how much current the
PNA draws, and how much heat the PNA's backlight and other circuitry
generates. You'll need to experiment to find out, I'm afraid. And then
you've still got some leeway, probably, because I suspect that the
lithium plating doesn't start immediately at 0C and it will also depend
on the charging current.

Now I think about it, I have a sort of partial, vague, sort-of datapoint.

Recently The staff members of The Register, an online technical mag,
dropped a paper aeroplane from 89,500 ft using a large weather balloon.
It also carried payload in the shape of a box made from thick foam and
containing a GPS tracker, a video camera, a still camera that took a
photo every 10 secs and at least one chemical hand-warmer. The still
camera quit on the way up at the cloud tops but the video ran for the
whole flight, which lasted around 2.5 hours, so (surprise!) it looks as
if you need a reasonable current drain to keep the battery warm.
Unfortunately the mission wasn't instrumented enough to record
temperature and the flight trace has no timestamps. Details are here if
you're interested:

http://www.theregister.co.uk/science/paris/

As for your second question, what you propose is exactly what I think
you should do. I keep my iPAQ on charge at home and also charge it in my
car until just before I put it in the cockpit, when the ship's power
takes over keeping the charge up.

That's good to know. Thanks.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

In article ,
Eric Greenwell wrote:

* the cell phone, laptop, power tool batteries are high volume
production products. My guess is they are likely more consistent
in quality than buying hand assembled, small batch (or only
one-at-a-time) units.
* they all have dedicated, proprietary chargers that plug in to only
their intended battery

Are you referring to internal charging circuitry with this last item?
Because many (most?) cell phones will charge off any standard USB port,
as long as you have the appropriate cable (and many can use a standard
USB cable for it). I believe the batteries themselves have enough
circuitry that the external charger doesn't need to be all that good to
keep things safe.

I agree with your point overall. While I carry my cell phone with me in
flight without a second thought, I'd be hesitant to have an order of
magnitude more battery capacity on board in Li-ion form.

--
Mike Ash
Radio Free Earth
Broadcasting from our climate-controlled studios deep inside the Moon

On Nov 14, 5:32*pm, Mike Ash wrote:
In article ,
*Eric Greenwell wrote:

* * * the cell phone, laptop, power tool batteries are high volume
* * * production products. My guess is they are likely more consistent
* * * in quality than buying hand assembled, small batch (or only
* * * one-at-a-time) units.
* * * they all have dedicated, proprietary chargers that plug in to only
* * * their intended battery

Are you referring to internal charging circuitry with this last item?
Because many (most?) cell phones will charge off any standard USB port,
as long as you have the appropriate cable (and many can use a standard
USB cable for it). I believe the batteries themselves have enough
circuitry that the external charger doesn't need to be all that good to
keep things safe.

I agree with your point overall. While I carry my cell phone with me in
flight without a second thought, I'd be hesitant to have an order of
magnitude more battery capacity on board in Li-ion form.

--
Mike Ash
Radio Free Earth
Broadcasting from our climate-controlled studios deep inside the Moon


Lithium batteries come in many chemistries - some with problematic
safety, others as safe as any battery can be. To group them all under
the heading "lithium-ion" is at best uninformed. Many of us will soon
be driving around with several hundred pounds of "lithium-ion" in our
cars.

One of the safest and best is "Lithium Iron Phosphate" (LiFePo4)
chemistry. This safety comes at the cost of lower energy density than
is typical of cell-phone or laptop batteries but they are still far
more energy dense than any lead battery. They also have a discharge
voltage curve which allows full use of their capacity.

On 11/14/2010 4:32 PM, Mike Ash wrote:
In ,
Eric wrote:


* the cell phone, laptop, power tool batteries are high volume
production products. My guess is they are likely more consistent
in quality than buying hand assembled, small batch (or only
one-at-a-time) units.
* they all have dedicated, proprietary chargers that plug in to only
their intended battery

Are you referring to internal charging circuitry with this last item?
Because many (most?) cell phones will charge off any standard USB port,
as long as you have the appropriate cable (and many can use a standard
USB cable for it). I believe the batteries themselves have enough
circuitry that the external charger doesn't need to be all that good to
keep things safe.

I agree with your point overall. While I carry my cell phone with me in
flight without a second thought, I'd be hesitant to have an order of
magnitude more battery capacity on board in Li-ion form.

I'm pretty sure the charge control circuitry is in the cell phone, the
Ipaq, or the laptop itself, not in it's battery, and the "charger" that
plugs into the wall is really only a power supply without a charge
regulator. It's not obvious from my writing, but that's what I meant by
the "proprietary chargers that plug in to only their intended battery".
The cell phone and Ipaq batteries I've seen are single cell units;
laptop batteries are multiple cell in series (and some are multiple
series units in parallel).

The K2 battery in the Soaring article looks interesting, and is closest
I've seen to a drop-in replacement, but the datasheet was sparse. It
didn't go into what protection circuitry was installed in the box, or
what the charger was like. It seems very "one-off" to me, and I'd like
more data and more field history before committing to one.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarm http://tinyurl.com/yb3xywl
- "A Guide to Self-launching Sailplane Operation Mar/2004" Much of what you need to know tinyurl.com/yfs7tnz

The battery in an Ipaq is a flat foil covered package, I wish now that
I had opened up the one I burned. The 12 volt batteries that I was
working with, that I gave a link to, are composed of 3 similar flat
foil packages, each when opened have a long narrow circuit board along
the top. These apparently 'turn off' the battery when you dead short
or put to much load on them and probably have other protective
properties as well. Under some conditions these will fail and at that
point I could never get the battery to work again.

Brian