More grist for the battle of the battery

[Bill Daniels]

Lithium Ion rechargeables seem to have recently seen a 50% or so price drop.
A 4-cell, 14.8V, 8AH with charger and mounting plate can be had for $169.99
(USD). These are basically long endurance laptop batteries.

This is still too much for me given that a SLA with the same capacity is
around $25 but the downward price trend is hopeful. Someone contemplating a
transponder, electric T&B and other juice hungry gadgets in a $100,000+
glider might see Li-Ion as a possibility now.

Beyond price, my concern is voltage. 4-cell Li-Ion packs produce 14.8V and
a detail in the spec sheet admits that a new, fully charged pack might
produce 16.2V into a high resistance load. My avionics manuals say 16V max.
Is that 0.2V overvoltage likely to be a problem?

Bill Daniels

[01-- Zero One]

Probably OK. However, if you are really concerned, one option is to put
a Schottky diode (of sufficient current capacity) in line. It will
introduce approximately 0.5v of voltage drop over the whole range of
supplied voltage.



Larry





"Bill Daniels" > wrote in message
:

> Lithium Ion rechargeables seem to have recently seen a 50% or so price drop.
> A 4-cell, 14.8V, 8AH with charger and mounting plate can be had for $169.99
> (USD). These are basically long endurance laptop batteries.
>
> This is still too much for me given that a SLA with the same capacity is
> around $25 but the downward price trend is hopeful. Someone contemplating a
> transponder, electric T&B and other juice hungry gadgets in a $100,000+
> glider might see Li-Ion as a possibility now.
>
> Beyond price, my concern is voltage. 4-cell Li-Ion packs produce 14.8V and
> a detail in the spec sheet admits that a new, fully charged pack might
> produce 16.2V into a high resistance load. My avionics manuals say 16V max.
> Is that 0.2V overvoltage likely to be a problem?
>
> Bill Daniels

[nimbusgb]

I have two NiMh packs in my Nimbus.

One replaces a 7.5 Ah SLA, its 2/3 the size of the SLA, half the weight
and its capacity is nominally 9 Ah but it delivers more like 10.5 given
my discharge curve. The other is a replacement for the lead brick of an
18 AH SLA in the nose, weighs 1/2 the 18 AH, nominally rated at 13 Ah
and delivers about 16.

Yes I have a switchable diode to ensure I don't over volatage the panel
when the cells are topped right off. I did have a small problem with a
Colibri logger that went haywire on 17 volts ( in spite of what the ,
now corrected, manual said )

Charging also requires a microprocessor controlled specialised charger.

The batteries perform extremely well over a wide temperatire range.
I have saved about 5 kg of weight right in the nose of the ship.
The extra voltage is good for the radio range.
The current capacity and voltage of the system spins up my 14v Horizon
in about 90 seconds ( 3 turns before going into cloud if left late )

[Tom]

Bill,

I strongly discourage you from considering lithium batteries for use in
your glider. A lithium fire, once started, is virtually impossible to
put out. Putting water on burning lithium actually feeds the fire (it
generates hydrogen). I read about one incident involving a laptop
battery that caught fire: he ended up throwing the entire laptop with
burning battery into a snow bank, which only intensified the fire.
Improper charging of lithium batteries are the primary, but not only,
cause of these fires. An enlightening report on the subject is at:

http://www.ntsb.gov/publictn/2005/HZB0501.pdf

Tom Seim
Richland, WA

Bill Daniels wrote:
> Lithium Ion rechargeables seem to have recently seen a 50% or so price drop.
> A 4-cell, 14.8V, 8AH with charger and mounting plate can be had for $169.99
> (USD). These are basically long endurance laptop batteries.
>
> This is still too much for me given that a SLA with the same capacity is
> around $25 but the downward price trend is hopeful. Someone contemplating a
> transponder, electric T&B and other juice hungry gadgets in a $100,000+
> glider might see Li-Ion as a possibility now.
>
> Beyond price, my concern is voltage. 4-cell Li-Ion packs produce 14.8V and
> a detail in the spec sheet admits that a new, fully charged pack might
> produce 16.2V into a high resistance load. My avionics manuals say 16V max.
> Is that 0.2V overvoltage likely to be a problem?
>
> Bill Daniels

[Bill Daniels]

"Tom" > wrote in message
oups.com...
> Bill,
>
> I strongly discourage you from considering lithium batteries for use in
> your glider. A lithium fire, once started, is virtually impossible to
> put out. Putting water on burning lithium actually feeds the fire (it
> generates hydrogen). I read about one incident involving a laptop
> battery that caught fire: he ended up throwing the entire laptop with
> burning battery into a snow bank, which only intensified the fire.
> Improper charging of lithium batteries are the primary, but not only,
> cause of these fires. An enlightening report on the subject is at:
>
> http://www.ntsb.gov/publictn/2005/HZB0501.pdf
>
> Tom Seim
> Richland, WA

Nice history, but today you will find dozens of Lithium-Ion batteries in a
typical airline cabin. Every gadget comes with one. 90% of the citizenry
has at least one in their pockets. I have carried a Li-Ion powered cell
phone for years. A Li-Ion fire in an airline cabin, or in junior's cargo
shorts, would be the lead story on the evening news. You don't hear it
because it doesn't happen.

I'd guess that most XC glider pilots already have two Li-Ion powered devices
in their cockpits - a PDA and a cellphone.

Yes, in EXTREMELY rare occasions there can be a problem - usually a product
recall for a 'warm' device with a wiring problem. A shorted 7AH SLA won't
be pretty either. The safety issue is an old story that has been almost
completely overcome with new designs.


Bill Daniels

[Marc Ramsey]

Bill Daniels wrote:
> Yes, in EXTREMELY rare occasions there can be a problem - usually a product
> recall for a 'warm' device with a wiring problem. A shorted 7AH SLA won't
> be pretty either. The safety issue is an old story that has been almost
> completely overcome with new designs.

Most "Li-ion" batteries contain Li-polymer cells these days. Having
witnessed the spectacular results of incorrectly charging a 6 cell model
airplane Li-poly battery pack (luckily, outdoors on concrete), I can
easily see Tom's point. I've found a video (complete with kewl music),
the batteries we'd use would be about 5 or 10 times this size:

http://www.helihobby.com/videos/LithiumBattery.wmv

A battery pack produced by a reputable manufacturer with a matched
charger, and proper short circuit protection, is probably safe. But, if
people start lashing up Li-poly packs and chargers the way we do with
SLAs, sooner or later someone will regret it. NiMH is much safer when
mishandled, and still offers an improvement in size/capacity over SLA...

Marc

[Tom]

I am quite aware of the broad use of lithiums. The hazard imposed,
however, is a function of the size of the battery and the mass of
lithium. A shorted SLA will blow a fuse (if there is a fuse), but it
won't catch fire. If a lithium battery catches fire it will burn until
the lithium is consumed. That may be ok for a PDA or flashlight, but
not a main battery in an aircraft, IMO. The issue is with the lithium
itself; no lithium battery design will eliminate that. Your battery
will likely be constructed from many individual cells. The failure of a
single cell will start the whole pack on fire. Fires on board aircraft
are rare in general, but when the occur they are very serious
situations.

BTW the successful use of a totally different product than the one you
are contemplating DOES NOT constitute a safety analysis. But the tone
of your reply suggests that I am wasting my time here.

Tom

[Eric Greenwell]

Bill Daniels wrote:
> Lithium Ion rechargeables seem to have recently seen a 50% or so price drop.
> A 4-cell, 14.8V, 8AH with charger and mounting plate can be had for $169.99
> (USD).

Can you supply a URL? While I strongly discourage people from making up
their own Li-ion battery packs for their glider due to potential safety
problems, a _production_ battery pack with it's dedicated charger would
likely alleviate most of the concerns I have about using a large Li-ion
battery in a glider. I don't worry about the little ones in my PDA, cell
phone, or camera.

> These are basically long endurance laptop batteries.

What would be the advantage of this battery over the 12 volt, 7 to 9
amphour SLA for your application? Neither size nor weight seem important
in a battery of only 8 amphours, whether SLA or Li-ion. That's a Nimbus
you fly, right?

>
> This is still too much for me given that a SLA with the same capacity is
> around $25 but the downward price trend is hopeful. Someone contemplating a
> transponder, electric T&B and other juice hungry gadgets in a $100,000+
> glider might see Li-Ion as a possibility now.

Unless it allows the pilot to mount significantly more capacity in the
original battery box, eliminating the need to find a place to mount more
batteries, I don't see any benefit. Saving a few pounds seems pointless
in most gliders, even a SparrowHawk.

>
> Beyond price, my concern is voltage. 4-cell Li-Ion packs produce 14.8V and
> a detail in the spec sheet admits that a new, fully charged pack might
> produce 16.2V into a high resistance load. My avionics manuals say 16V max.
> Is that 0.2V overvoltage likely to be a problem?

"Probably not", but I don't know how much margin is built into that
specification. Routinely operating at the high end of the voltage range
might be a different situation than the specification addresses. Ask the
manufacturer, I think.

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

Eric Greenwell
Washington State
USA

[Bill Daniels]

"Eric Greenwell" > wrote in message
...
> Bill Daniels wrote:
> > Lithium Ion rechargeables seem to have recently seen a 50% or so price
drop.
> > A 4-cell, 14.8V, 8AH with charger and mounting plate can be had for
$169.99
> > (USD).
>
> Can you supply a URL? While I strongly discourage people from making up
> their own Li-ion battery packs for their glider due to potential safety
> problems, a _production_ battery pack with it's dedicated charger would
> likely alleviate most of the concerns I have about using a large Li-ion
> battery in a glider. I don't worry about the little ones in my PDA, cell
> phone, or camera.

I just scanned a bunch of pages from a Google search. I'll find the one
with the specifics.

>
> > These are basically long endurance laptop batteries.
>
> What would be the advantage of this battery over the 12 volt, 7 to 9
> amphour SLA for your application? Neither size nor weight seem important
> in a battery of only 8 amphours, whether SLA or Li-ion. That's a Nimbus
> you fly, right?
>
It's about a 6 pound weight savings. (1 Lb vs 7 Lbs) for 7-8 AH. That
allows the battery to be behind the panel with short wires instead of behind
the seat with long wires. Total weight savings are not that important but
the battery's effect on balance and weight of the 'non-flying' parts is.
I've been running W&B's and 6 pounds is important.

> > This is still too much for me given that a SLA with the same capacity is
> > around $25 but the downward price trend is hopeful. Someone
contemplating a
> > transponder, electric T&B and other juice hungry gadgets in a $100,000+
> > glider might see Li-Ion as a possibility now.
>
> Unless it allows the pilot to mount significantly more capacity in the
> original battery box, eliminating the need to find a place to mount more
> batteries, I don't see any benefit. Saving a few pounds seems pointless
> in most gliders, even a SparrowHawk.

You can get a lot more capacity for the same volume and weight.
>

As for safety, the motorglider guys are flying around with GASOLINE, right?
That burns too.

Bill Daniels

[Bill Daniels]

"Marc Ramsey" > wrote in message
...
> Bill Daniels wrote:
> > Yes, in EXTREMELY rare occasions there can be a problem - usually a
product
> > recall for a 'warm' device with a wiring problem. A shorted 7AH SLA
won't
> > be pretty either. The safety issue is an old story that has been almost
> > completely overcome with new designs.
>
> Most "Li-ion" batteries contain Li-polymer cells these days. Having
> witnessed the spectacular results of incorrectly charging a 6 cell model
> airplane Li-poly battery pack (luckily, outdoors on concrete), I can
> easily see Tom's point. I've found a video (complete with kewl music),
> the batteries we'd use would be about 5 or 10 times this size:
>
> http://www.helihobby.com/videos/LithiumBattery.wmv
>
> A battery pack produced by a reputable manufacturer with a matched
> charger, and proper short circuit protection, is probably safe. But, if
> people start lashing up Li-poly packs and chargers the way we do with
> SLAs, sooner or later someone will regret it. NiMH is much safer when
> mishandled, and still offers an improvement in size/capacity over SLA...
>
> Marc

I'm not suggesting lash-ups. A discrete 'brick' or 'slab' battery pack with
matched charger is what I am talking about.

I've read the warnings from the model airplane sites. The warnings seem to
all be about charging. I never charge a battery in the glider.

Bill Daniels

[Marc Ramsey]

Bill Daniels wrote:
> I'm not suggesting lash-ups. A discrete 'brick' or 'slab' battery pack with
> matched charger is what I am talking about.

Well, that is what you would do, but you are more careful than most...

> I've read the warnings from the model airplane sites. The warnings seem to
> all be about charging. I never charge a battery in the glider.

Look more carefully, there are also warnings about explosions resulting
from short circuits. I've seen a similar video where they just shorted
the terminals together, and let the cell sit for a minute or two...

Marc

[Eric Greenwell]

Bill Daniels wrote:

>>What would be the advantage of this battery over the 12 volt, 7 to 9
>>amphour SLA for your application? Neither size nor weight seem important
>>in a battery of only 8 amphours, whether SLA or Li-ion. That's a Nimbus
>>you fly, right?
>>
>
> It's about a 6 pound weight savings. (1 Lb vs 7 Lbs) for 7-8 AH. That
> allows the battery to be behind the panel with short wires instead of behind
> the seat with long wires. Total weight savings are not that important but
> the battery's effect on balance and weight of the 'non-flying' parts is.
> I've been running W&B's and 6 pounds is important.

This is an interesting idea. It might be an easy way to power a
transponder with a separate battery, without the hassle and expense of
mounting a 6 pound battery somewhere it won't become a projectile.

The Becker and Microair transponders have max input voltages of 30
volts, so no problem with 16.2 full charge voltage that's an issue for
you. Encoders, like the ACK 30 I use, have similar values. It would mean
using two different chargers, one for the Li-ion, one for the SLA, but
that seems like a minor inconvenience.

snip

> As for safety, the motorglider guys are flying around with GASOLINE, right?
> That burns too.

Surprisingly, fire fed by the gasoline is a rare event in motorgliders
(wire fires seem more common, along with burns from the canopy focusing
the sun), and we continue to hurt ourselves in the usual ways glider
pilots do.


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

Eric Greenwell
Washington State
USA

[COLIN LAMB]

A Lear Jet caught fire when a battery overheated and burned a hole in the
fuselage. This was caused because the new battery had such a tremendous
current capacity. No, it was not a lithium ion, it was a nicad. That was
about 35 years ago and the FAA issued cautions about the problems created by
nicad batteries.

I have also read about people being seriously burned when the nicad
batteries they were carrying in their pocket shorted out on their keys,
burning a hole in their pants and in one case leaving an imprint on the
thigh of the victim.

Any device that stores or creates energy is a potential hazard. What is
required is that the user understand the potential hazards and minimize the
risks.

We drive around in cars full of gasoline, which may burn or explode in an
accident, on tires that may suddenly deflate because of an object striking
them. And, we are 4 feet away from a vehicle coming the opposite direction
going 50 miles per hour. Sometimes where we draw the line between what is
safe and what is not is rather arbitrary.

Colin

[Don Johnstone]

At 02:12 15 November 2005, Marc Ramsey wrote:
>Bill Daniels wrote:
>> I'm not suggesting lash-ups. A discrete 'brick' or
>>'slab' battery pack with
>> matched charger is what I am talking about.
>
>Well, that is what you would do, but you are more careful
>than most...
>
>> I've read the warnings from the model airplane sites.
>> The warnings seem to
>> all be about charging. I never charge a battery in
>>the glider.
>
>Look more carefully, there are also warnings about
>explosions resulting
>from short circuits. I've seen a similar video where
>they just shorted
>the terminals together, and let the cell sit for a
>minute or two...

There is a cure for that, a fuse. Regs in the UK require
a fuse within a very short distance from the batttery,
2.5 ins from memory and I use 3 amp. Not a lot of opportunity
for a short of any sustained time with that arrangement
if the terminals are insulated as they should be.
A standard lead acid battery will do very spectacular
things if shorted out as well, I remember (many many
years ago when young) trying to light a cigarette using
a strand of winch wire across the winch battery terminals,
worked fine until the top blew off the battery. It
would seem that even then smoking could damage your
health.

PS You needed a good pair of gloves :-). I think we
might have invented the automobile cigar lighter without
knowing it.


>

[Vaughn]

"Don Johnstone" > wrote in
message ...
> At 02:12 15 November 2005, Marc Ramsey wrote:
>
> There is a cure for that, a fuse.

True, but there is no fuse that can protect from an internal short circuit.
Any type of battery can (at least rarely) do this. I have seen both lead acid
and NIMH batteries burn up this way. (It the case of the NIMH it was an irate
firefighter whose portable radio had nearly caught fire.) Naturally, the more
energy in the cell, the more heat, smoke, and (possibly) flames you can expect.
Lithium batteries have a very high energy density and the innards love to burn,
so internal shorts are a particular concern with them.

How great is the danger as a practical matter? That is the true question
here!

Vaughn

[Martin Gregorie]

COLIN LAMB wrote:
.../..
> I have also read about people being seriously burned when the nicad
> batteries they were carrying in their pocket shorted out on their keys,
> burning a hole in their pants and in one case leaving an imprint on the
> thigh of the victim.
>
There was story in Model Aviation a few years ago about just that
happening to an RC model flier. He put his NiCd glow-starter in the same
pocket as his keys without capping it. Unfortunately his pocket also
held half a dozen .45 cartridges from the morning's target practice....

--
martin@ | Martin Gregorie
gregorie. |
org | Zappa fan & glider pilot

[Bill Daniels]

"Eric Greenwell" > wrote in message
...
> Bill Daniels wrote:
> > Lithium Ion rechargeables seem to have recently seen a 50% or so price
drop.
> > A 4-cell, 14.8V, 8AH with charger and mounting plate can be had for
$169.99
> > (USD).
>
> Can you supply a URL? While I strongly discourage people from making up
> their own Li-ion battery packs for their glider due to potential safety
> problems, a _production_ battery pack with it's dedicated charger would
> likely alleviate most of the concerns I have about using a large Li-ion
> battery in a glider. I don't worry about the little ones in my PDA, cell
> phone, or camera.

Sometimes Froogle doesn't find the same things on successive searches. Here
is an example of what I'm talking about.

http://store.linkexpresspc.com/de16liprbafo.html

Specifications:
- Rating: 14.8V == DOUBLE CAPACITY 8800mAH (8.8AH)
- Capacity : 132 WHR 16CELL
$149.00 @ LinkExpressPC

As for the warning videos and scary stories in the press, most people know
these are merely efforts at proactive legal defense. (Lawyer for the
plaintiff: "You sold these CHEMICAL FIRE BOMBS for use in CHILDREN'S TOY
AIRPLANES?) (Lawyer for the defense: "Gee, yer honor, we warned 'em - see
our scary video on the web.) It's an effort to immunize the manufacturer
against 'frivolous' lawsuits.

In fact, most technically savvy users know Li-Ion batteries are plenty safe
if a few simple precautions are used. Mainly, use the correct charger in a
fire safe location. Once charged, don't damage the case or short them.
That's pretty good advice for any rechargeable battery no matter the
chemistry.

Bill Daniels

[Eric Greenwell]

Vaughn wrote:

> "Don Johnstone" > wrote in
> message ...
>
>>
>>There is a cure for that, a fuse.
>
> True, but there is no fuse that can protect from an internal short circuit.
> Any type of battery can (at least rarely) do this. I have seen both lead acid
> and NIMH batteries burn up this way. (It the case of the NIMH it was an irate
> firefighter whose portable radio had nearly caught fire.) Naturally, the more
> energy in the cell, the more heat, smoke, and (possibly) flames you can expect.
> Lithium batteries have a very high energy density and the innards love to burn,
> so internal shorts are a particular concern with them.
>
> How great is the danger as a practical matter? That is the true question
> here!

Indeed; however, there are a jillion laptop batteries in use, but very
few problems (I haven't heard of any, but there must be some). For
glider use, I'd want to know what the usable temperature range is (some
units specify only up to 95 deg. F), what altitude they can be used to
(haven't seen any specifications for that), and what safety features are
built into them (fuses, both for amps and overheating, might be
standard, and welcome, features, for example).


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

Eric Greenwell
Washington State
USA

[Eric Greenwell]

Bill Daniels wrote:

>>Can you supply a URL? While I strongly discourage people from making up
>>their own Li-ion battery packs for their glider due to potential safety
>>problems, a _production_ battery pack with it's dedicated charger would
>>likely alleviate most of the concerns I have about using a large Li-ion
>>battery in a glider. I don't worry about the little ones in my PDA, cell
>>phone, or camera.
>
>
> Sometimes Froogle doesn't find the same things on successive searches. Here
> is an example of what I'm talking about.
>
> http://store.linkexpresspc.com/de16liprbafo.html
>
> Specifications:
> - Rating: 14.8V == DOUBLE CAPACITY 8800mAH (8.8AH)
> - Capacity : 132 WHR 16CELL
> $149.00 @ LinkExpressPC

I think this style would be much more suitable than a laptop battery:

http://tinyurl.com/8zl55

Essentially the same ratings and price ($169 with charger), it has a
standard output connector and a easier to mount shape. Google "external
laptop battery" without the quotes. There is a wide range of price and
power in this style. Something like this might be very practical for
gliders, though I still want to know more about maximum ambient
temperature and altitude allowed, and built-in safety features.

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

Eric Greenwell
Washington State
USA

[Bill Daniels]

"Eric Greenwell" > wrote in message
...
> Bill Daniels wrote:
>
> >>Can you supply a URL? While I strongly discourage people from making up
> >>their own Li-ion battery packs for their glider due to potential safety
> >>problems, a _production_ battery pack with it's dedicated charger would
> >>likely alleviate most of the concerns I have about using a large Li-ion
> >>battery in a glider. I don't worry about the little ones in my PDA, cell
> >>phone, or camera.
> >
> >
> > Sometimes Froogle doesn't find the same things on successive searches.
Here
> > is an example of what I'm talking about.
> >
> > http://store.linkexpresspc.com/de16liprbafo.html
> >
> > Specifications:
> > - Rating: 14.8V == DOUBLE CAPACITY 8800mAH (8.8AH)
> > - Capacity : 132 WHR 16CELL
> > $149.00 @ LinkExpressPC
>
> I think this style would be much more suitable than a laptop battery:
>
> http://tinyurl.com/8zl55
>
> Essentially the same ratings and price ($169 with charger), it has a
> standard output connector and a easier to mount shape. Google "external
> laptop battery" without the quotes. There is a wide range of price and
> power in this style. Something like this might be very practical for
> gliders, though I still want to know more about maximum ambient
> temperature and altitude allowed, and built-in safety features.
>
> --
> Change "netto" to "net" to email me directly
>
> Eric Greenwell
> Washington State
> USA

Yep, that's a better example. I think I saw that one on my earlier search
but I couldn't find it the second time. There are quite a few of these on
the market from a variety of vendors. The price is falling as they become a
commodity. I think I could build a box for an internal laptop battery that
would have contacts and a restraining latch. Just push the battery in until
it clicks - no wires to futz with.

Many laptops and gadgets sit on car seats in the sun and then get turned on.
I have certainly done that but I don't know of any problems. I remember
trying to boot a laptop I left on a car seat in Phoenix. It was so hot I
couldn't hold it. After it booted, I couldn't read the LCD until the A/C
cooled it down. Generically, Li-ion polymer batteries are tolerant of
temperature extremes. The laptop batteries are regarded as 'smart'
batteries in that they have processor chips inside that manage them. I
think they may even limit the voltage to 14.8V.

Bill Daniels

[Don Johnstone]

Er.........The Antares is powered by Li-ion batteries
capable of delivering 42kW, the blurb actually says
limited to 42kW for safety reasons which would imply
it is capable of more. Are we perhaps worrying about
a problem that has been solved?

http://www.lange-flugzeugbau.de/bilder/pdf/daten-batterie-engl.pdf


It is in english


At 18:42 15 November 2005, Bill Daniels wrote:
>
>'Eric Greenwell' wrote in message
...
>> Bill Daniels wrote:
>>
>> >>Can you supply a URL? While I strongly discourage
>>>>people from making up
>> >>their own Li-ion battery packs for their glider due
>>>>to potential safety
>> >>problems, a _production_ battery pack with it's dedicated
>>>>charger would
>> >>likely alleviate most of the concerns I have about
>>>>using a large Li-ion
>> >>battery in a glider. I don't worry about the little
>>>>ones in my PDA, cell
>> >>phone, or camera.
>> >
>> >
>> > Sometimes Froogle doesn't find the same things on
>>>successive searches.
>Here
>> > is an example of what I'm talking about.
>> >
>> > http://store.linkexpresspc.com/de16liprbafo.html
>> >
>> > Specifications:
>> > - Rating: 14.8V == DOUBLE CAPACITY 8800mAH (8.8AH)
>> > - Capacity : 132 WHR 16CELL
>> > $149.00 @ LinkExpressPC
>>
>> I think this style would be much more suitable than
>>a laptop battery:
>>
>> http://tinyurl.com/8zl55
>>
>> Essentially the same ratings and price ($169 with
>>charger), it has a
>> standard output connector and a easier to mount shape.
>>Google 'external
>> laptop battery' without the quotes. There is a wide
>>range of price and
>> power in this style. Something like this might be
>>very practical for
>> gliders, though I still want to know more about maximum
>>ambient
>> temperature and altitude allowed, and built-in safety
>>features.
>>
>> --
>> Change 'netto' to 'net' to email me directly
>>
>> Eric Greenwell
>> Washington State
>> USA
>
>Yep, that's a better example. I think I saw that one
>on my earlier search
>but I couldn't find it the second time. There are
>quite a few of these on
>the market from a variety of vendors. The price is
>falling as they become a
>commodity. I think I could build a box for an internal
>laptop battery that
>would have contacts and a restraining latch. Just
>push the battery in until
>it clicks - no wires to futz with.
>
>Many laptops and gadgets sit on car seats in the sun
>and then get turned on.
>I have certainly done that but I don't know of any
>problems. I remember
>trying to boot a laptop I left on a car seat in Phoenix.
> It was so hot I
>couldn't hold it. After it booted, I couldn't read
>the LCD until the A/C
>cooled it down. Generically, Li-ion polymer batteries
>are tolerant of
>temperature extremes. The laptop batteries are regarded
>as 'smart'
>batteries in that they have processor chips inside
>that manage them. I
>think they may even limit the voltage to 14.8V.
>
>Bill Daniels
>
>

[Tom]

Again, you shouldn't extrapolate from one product design to another
totally different design, especially in regards to safety. Each cell of
the Antares has it's own microprocessor that monitors the health and
charge of that cell. All of these microprocessors are networked
together to a central processor. In other words, this is a total system
engineered for flight that has passed stringent mandated testing.

Eric brought up the altitude issue. We fly at (sometimes) at extremely
high altitudes. This has a direct impact on component engineering. It
is very common to see components restricted to altitudes less than 10K
feet. Having no altitude spec whatsoever is quite disturbing to me.

Tom

[John Ferguson]

Been reading this thread and found the discussion quite
interesting, interesting enough to go looking. I found
this site selling L-ION batteries, charge protectors
and special L-ION chargers all at very reasonable prices.

http://www.batteryspace.com/index.asp?PageAction=VIEWCATS&Category
=489

One part of this discussion has been about not doing
it yourself, would making a battery out of these parts
constitute doing it yourself for someone reasonably
proficient and capable of taking care in assembly of
such a pack.

I fly a turbo and regaining about 6 kilo of battery
weight is attractive as I stand about 90 kilos ready
to fly.

John

[John Ferguson]

Been reading this thread and found the discussion quite
interesting, interesting enough to go looking. I found
this site selling L-ION batteries, charge protectors
and special L-ION chargers all at very reasonable prices.

http://www.batteryspace.com/index.asp?PageAction=VIEWCATS&Category
=489

One part of this discussion has been about not doing
it yourself, would making a battery out of these parts
constitute doing it yourself for someone reasonably
proficient and capable of taking care in assembly of
such a pack.

I fly a turbo and regaining about 6 kilo of battery
weight is attractive as I stand about 90 kilos ready
to fly.

John

[Eric Greenwell]

John Ferguson wrote:
> Been reading this thread and found the discussion quite
> interesting, interesting enough to go looking. I found
> this site selling L-ION batteries, charge protectors
> and special L-ION chargers all at very reasonable prices.
>
> http://www.batteryspace.com/index.asp?PageAction=VIEWCATS&Category
> =489
>
> One part of this discussion has been about not doing
> it yourself, would making a battery out of these parts
> constitute doing it yourself for someone reasonably
> proficient and capable of taking care in assembly of
> such a pack.

I don't intend to be facetious when I say "If you have to ask, don't do
it yourself!" Assembling the pack is not the issue, but charging it
properly and protecting it from overheating, mechanical damage, and
probably other issues I'm not familiar with. Li-ion cells are not
tolerant of poor charging methods compared to lead acid cells, ni-cads,
or even Ni-mh cells. The external laptop batteries we are discussing are
packaged units designed and manufactured expressly for that use, and
come with a charger matched to the unit, so I think they would work
better and be much safer than most of us could construct. Even so, it's
not obvious (yet) that they are actually compatible with glider usage,
given the temperature and altitude ranges we fly in.

> I fly a turbo and regaining about 6 kilo of battery
> weight is attractive as I stand about 90 kilos ready
> to fly.

Are you thinking of using a Li-ion battery for the starter battery?
Don't even think of going there!

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

Eric Greenwell
Washington State
USA

[Eric Greenwell]

Bill Daniels wrote:

I think I could build a box for an internal laptop battery that
> would have contacts and a restraining latch. Just push the battery in until
> it clicks - no wires to futz with.

Perhaps a suitable solution for a knowledgeable person like yourself,
but the typical laptop battery has a half-dozen contacts, so I wouldn't
know which ones need connecting. I don't even know if the charger can be
connected directly to battery, or if it goes through some other
circuitry in the laptop. These issues don't exist with external laptop
batteries, and their approximately 4" x 6" x 1" shape would make
mounting them easier than the oddball shapes the laptops use. We already
futz with one cable out a lead-acid glider battery - not a problem there.

>
> Many laptops and gadgets sit on car seats in the sun and then get turned on.
> I have certainly done that but I don't know of any problems. I remember
> trying to boot a laptop I left on a car seat in Phoenix. It was so hot I
> couldn't hold it. After it booted, I couldn't read the LCD until the A/C
> cooled it down. Generically, Li-ion polymer batteries are tolerant of
> temperature extremes. The laptop batteries are regarded as 'smart'
> batteries in that they have processor chips inside that manage them.

I don't know how smart a laptop battery is, and I suspect some of the
smarts are inside the laptop; for example, in the situation you
describe, the laptop likely cut back it's processor speed and LCD
brightness to reduce the power taken from the battery, protecting it
from overheating. The battery used by itself might not be able to
protect itself properly, because it's designed to be used only in the
laptop. The external batteries might offer this protection, since they
are intended to be used by themselves. I don't know if that's true, but
I'd like to know before I started using one in a glider.

> I think they may even limit the voltage to 14.8V.

A number of the external batteries can be set to different output
voltages, which might be useful, but I don't know how they do that.

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

Eric Greenwell
Washington State
USA

[Bill Daniels]

"Eric Greenwell" > wrote in message
...
> John Ferguson wrote:
> > Been reading this thread and found the discussion quite
> > interesting, interesting enough to go looking. I found
> > this site selling L-ION batteries, charge protectors
> > and special L-ION chargers all at very reasonable prices.
> >
> > http://www.batteryspace.com/index.asp?PageAction=VIEWCATS&Category
> > =489
> >
> > One part of this discussion has been about not doing
> > it yourself, would making a battery out of these parts
> > constitute doing it yourself for someone reasonably
> > proficient and capable of taking care in assembly of
> > such a pack.
>
> I don't intend to be facetious when I say "If you have to ask, don't do
> it yourself!" Assembling the pack is not the issue, but charging it
> properly and protecting it from overheating, mechanical damage, and
> probably other issues I'm not familiar with. Li-ion cells are not
> tolerant of poor charging methods compared to lead acid cells, ni-cads,
> or even Ni-mh cells. The external laptop batteries we are discussing are
> packaged units designed and manufactured expressly for that use, and
> come with a charger matched to the unit, so I think they would work
> better and be much safer than most of us could construct. Even so, it's
> not obvious (yet) that they are actually compatible with glider usage,
> given the temperature and altitude ranges we fly in.
>
> > I fly a turbo and regaining about 6 kilo of battery
> > weight is attractive as I stand about 90 kilos ready
> > to fly.
>
> Are you thinking of using a Li-ion battery for the starter battery?
> Don't even think of going there!
>
> --
> Change "netto" to "net" to email me directly
>
> Eric Greenwell
> Washington State
> USA

I don't think it's fair to say that Li-ion in some form wouldn't work as a
starter battery. It is fair to say we don't yet know all the issues
involved. And it's fair to say, as Eric does, that it isn't a DIY project.
Maybe it will be someday soon. Let someone else develop them for a similar
application and then adopt it.

Li-Ion will be used as hybrid car batteries as soon as the price is
workable. They are already being used in research electric vehicles in
Japan that get 400KM range @ 120KPH on a charge and then completely recharge
in 5 minutes. The main problem, other than the battery price, is that
should everybody plug them in at the same time, the power grid would melt.

DeWalt will be introducing a set of construction grade power tools that use
these fast charge Li-Ion Polymer batteries next year.

As for temperature and altitude, I just can't see that as a problem. The
pressure delta from sea level to 40,000 feet is something like 10 PSI. The
cases have to be much stronger than that for safety reasons. Low
temperatures might cause a battery not in use to not develop full power at
switch-on but one in use would maintain its own temperature.

Bill Daniels

[Eric Greenwell]

Bill Daniels wrote:

> I don't think it's fair to say that Li-ion in some form wouldn't work as a
> starter battery. It is fair to say we don't yet know all the issues
> involved.

I agree. I was addressing John's situation. I'm sure a competent battery
engineer could design a good starter battery, though the voltages
available in Li-ion might be challenge for a 12 volt starter.

snip

>
> As for temperature and altitude, I just can't see that as a problem. The
> pressure delta from sea level to 40,000 feet is something like 10 PSI. The
> cases have to be much stronger than that for safety reasons. Low
> temperatures might cause a battery not in use to not develop full power at
> switch-on but one in use would maintain its own temperature.

I suspect these batteries are probably fine for our conditions. The
problem (for me) is I don't know what's in the external laptop
batteries. Are all the components capable of 40,000'? If the pilot takes
off at 105 deg F with a battery at 130 deg F under the instrument
cowling and climbs to 20,000' in an hour, is the battery still OK, or is
it overheating under the load from the Ipaq, transponder, glide
computer, radio, etc.? Or maybe he just struggles around a few thousand
feet off the ground, while the battery temperature goes up? What then?

Sure, for pilots flying in temperatures under 90 deg F and less than
10,000', I'm not worried about the ambient conditions, but that leaves
out a lot of pilots in a lot of places.
--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA