More grist for the battle of the battery

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/bild...terie-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.

--
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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

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

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.as...WCATS&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

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.as...WCATS&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 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.as...WCATS&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

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

"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.as...WCATS&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

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