Lithium technology batteries

[Ken Kochanski (KK)]

Although the technology is still pricy vs lead-acid batteries, the
power/weight/size vs cost equation is getting better. Anybody using
lithium model airplane packs bundeled to produce 12 - 14 v @3 - 6 amps
as a power source for their glider? (I have been looking at the
duralite site ... I'm sure there are others.)
http://www.duralitebatteries.com/batteries.html

KiloKilo

[Bill Daniels]

"Ken Kochanski (KK)" > wrote in message
oups.com...
> Although the technology is still pricy vs lead-acid batteries, the
> power/weight/size vs cost equation is getting better. Anybody using
> lithium model airplane packs bundeled to produce 12 - 14 v @3 - 6 amps
> as a power source for their glider? (I have been looking at the
> duralite site ... I'm sure there are others.)
> http://www.duralitebatteries.com/batteries.html
>
> KiloKilo
>

I've been watching this too. (The model airplane guys always seem to grab
the latest technology and run with it.) The early Li-Po batteries had some
problems with catching fire when charging but it's clear that the technology
has come a long way in the last year.

There are 14V Mil-Spec Li-Po packs that would be safer to use but the prices
are still astronomical. There are also some 14.8V laptop computer battery
packs that look interesting.

One thing that worries me is that a freshly charged Li-Po "14.8V" pack will
produce a no-load voltage over 16V. A lot of avionics specify that the
maximum voltage is 16V.

Bill Daniels

[WilLiscomb]

voltage regulator
williscomb

[Vaughn]

"WilLiscomb" > wrote in message
...
> voltage regulator

...or just a forward-biased diode or three.

Vaughn

[Eric Greenwell]

Ken Kochanski (KK) wrote:

> Although the technology is still pricy vs lead-acid batteries, the
> power/weight/size vs cost equation is getting better. Anybody using
> lithium model airplane packs bundeled to produce 12 - 14 v @3 - 6 amps
> as a power source for their glider? (I have been looking at the
> duralite site ... I'm sure there are others.)
> http://www.duralitebatteries.com/batteries.html


Given the cost and careful charging requirements, I'm guessing the
interest in these is to allow more amphours to be stuffed into the
glider's original battery box? Eliminating the need for adding another
box when you added a transponder/Ipaq/etc would maybe make the Li
battery cost worthwhile. For example, from the Duralite site:

> The recommended
> safe charging procedure for all Li-ion & Li-Poly
> batteries is to charge them out of the aircraft in a �re
> proof area or container. Always be present during the
> charging cycle. Unplug the batteries from charger when
> charging cycle is complete.


Yikes!

I don't see any other advantages for gliders over the standard sealed
lead/acid batteries, which are cheap and trouble free.


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Eric Greenwell
Washington State
USA

[tango4]

"WilLiscomb" > wrote in message
...
> voltage regulator
> williscomb
>


Hmmmm

Build a 'better' battery so that you can dump power into a voltage
regulator. Cute.

Actually the forward biased semiconductor junction in the form of a diode is
a much easier way to do things.

Ian

[Tim Ward]

"Eric Greenwell" > wrote in message
...
> Ken Kochanski (KK) wrote:
>
> > Although the technology is still pricy vs lead-acid batteries, the
> > power/weight/size vs cost equation is getting better. Anybody using
> > lithium model airplane packs bundeled to produce 12 - 14 v @3 - 6 amps
> > as a power source for their glider? (I have been looking at the
> > duralite site ... I'm sure there are others.)
> > http://www.duralitebatteries.com/batteries.html
>
>
> Given the cost and careful charging requirements, I'm guessing the
> interest in these is to allow more amphours to be stuffed into the
> glider's original battery box? Eliminating the need for adding another
> box when you added a transponder/Ipaq/etc would maybe make the Li
> battery cost worthwhile. For example, from the Duralite site:
>
> > The recommended
> > safe charging procedure for all Li-ion & Li-Poly
> > batteries is to charge them out of the aircraft in a ?re
> > proof area or container. Always be present during the
> > charging cycle. Unplug the batteries from charger when
> > charging cycle is complete.
>
>
> Yikes!
>
> I don't see any other advantages for gliders over the standard sealed
> lead/acid batteries, which are cheap and trouble free.
>
>
> --
> Change "netto" to "net" to email me directly
>
> Eric Greenwell
> Washington State
> USA

Well, Li chemistry batteries have much better performance when it's cold
than either lead, NiCd or NiMH. So that might be a consideration for those
flying wave a lot.

Tim Ward

[Tim Ward]

"tango4" > wrote in message
...
>
> "WilLiscomb" > wrote in message
> ...
> > voltage regulator
> > williscomb
> >
>
>
> Hmmmm
>
> Build a 'better' battery so that you can dump power into a voltage
> regulator. Cute.
>
> Actually the forward biased semiconductor junction in the form of a diode
is
> a much easier way to do things.
>
> Ian
>
>

You could use a step-up switching regulator. This would, of course, have
the minor drawback of eliminating the annual "6 or 7 cell" argument on RAS.

Tim Ward

[Eric Greenwell]

Tim Ward wrote:

>>
>> Yikes!
>>
>> I don't see any other advantages for gliders over the standard
>> sealed lead/acid batteries, which are cheap and trouble free.


>
> Well, Li chemistry batteries have much better performance when it's
> cold than either lead, NiCd or NiMH. So that might be a consideration
> for those flying wave a lot.

I wondered about that, but didn't happen across any temperature specs.
Do you have a link to one for these types of batteries?

This pilot's performance when he's cold tends to drop off faster than
his battery's performance, unfortunately! Maybe Li batteries would be a
better way to supply power to heated socks and gloves than the usual
alkaline or NiCd.


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Eric Greenwell
Washington State
USA

[Atacdad]

I looked at these guys earlier this year. Unfortuneately, they did not have
an "off the shelf" solution. Lithium without the fire hazard....

http://www.valence.com

AT


"Ken Kochanski (KK)" > wrote in message
oups.com...
> Although the technology is still pricy vs lead-acid batteries, the
> power/weight/size vs cost equation is getting better. Anybody using
> lithium model airplane packs bundeled to produce 12 - 14 v @3 - 6 amps
> as a power source for their glider? (I have been looking at the
> duralite site ... I'm sure there are others.)
> http://www.duralitebatteries.com/batteries.html
>
> KiloKilo
>

[John Giddy]

On Sun, 19 Dec 2004 19:09:49 +0000 (UTC), tango4 wrote:

> "WilLiscomb" > wrote in message
> ...
>> voltage regulator
>> williscomb
>>
>
>
> Hmmmm
>
> Build a 'better' battery so that you can dump power into a voltage
> regulator. Cute.
>
> Actually the forward biased semiconductor junction in the form of a diode is
> a much easier way to do things.
>
> Ian

Only problem is that the voltage drop is also present at the
end-of-charge point, thus losing the last 0.7v of possible battery
voltage before things start working strangely.
If you use a well designed switching regulator which can boost as well
as buck, the voltage supplied to the instruments can be maintained in
the ideal range until the battery is almost completely flat, and at an
average efficiency of about 80%. AFAIK, complete discharge is not
harmful to NiCd, Lithium types etc. It is harmful to lead acid
batteries.
Cheers, John G.

[Bill Daniels]

"Tim Ward" > wrote in message
nk.net...
>
> "Eric Greenwell" > wrote in message
> ...
> > Ken Kochanski (KK) wrote:
> >
> > > Although the technology is still pricy vs lead-acid batteries, the
> > > power/weight/size vs cost equation is getting better. Anybody using
> > > lithium model airplane packs bundeled to produce 12 - 14 v @3 - 6
amps
> > > as a power source for their glider? (I have been looking at the
> > > duralite site ... I'm sure there are others.)
> > > http://www.duralitebatteries.com/batteries.html

> > > The recommended
> > > safe charging procedure for all Li-ion & Li-Poly
> > > batteries is to charge them out of the aircraft in a ?re
> > > proof area or container. Always be present during the
> > > charging cycle. Unplug the batteries from charger when
> > > charging cycle is complete.
> >

I think this applies only to the first generation electric powered model
airplane batteries. There are tens of millions of lithium ion and lithium
polymer cellphone batteries charged on nightstands with few problems. Where
there were problems it has turned out to be counterfeit made in China
aftermarket batteries. Even the second generation model airplane batteries
have pretty well put the fire problem behind them.

Why Li-Po? Well one reason is that their light weight allows them to be
placed just behind the instrument panel where very short power leads lose
less power. Heavy SLA's usually have to go behind the seat and use long
wires to the panel.

Bill Daniels

[Stephen Haley]

These retailers are expensive - go to the source
http://sabahoceanic.com/SearchResult.aspx?CategoryID=9
They will tag them for free
Use 8x BR-C and you will get 12V 10000mah for $128
(these are 3v cells as opposed to the normal 3.7v)

Can do it cheaper with some of the other cells

Used them to replace my laptop batts - fast efficient service. Downside is
that chargers & electronics are scarce
rgds
Stephen

"Atacdad" > wrote in message
...
>I looked at these guys earlier this year. Unfortuneately, they did not
>have an "off the shelf" solution. Lithium without the fire hazard....
>
> http://www.valence.com
>
> AT
>
>
> "Ken Kochanski (KK)" > wrote in message
> oups.com...
>> Although the technology is still pricy vs lead-acid batteries, the
>> power/weight/size vs cost equation is getting better. Anybody using
>> lithium model airplane packs bundeled to produce 12 - 14 v @3 - 6 amps
>> as a power source for their glider? (I have been looking at the
>> duralite site ... I'm sure there are others.)
>> http://www.duralitebatteries.com/batteries.html
>>
>> KiloKilo
>>
>
>

[Eric Greenwell]

Stephen Haley wrote:
> These retailers are expensive - go to the source
> http://sabahoceanic.com/SearchResult.aspx?CategoryID=9
> They will tag them for free
> Use 8x BR-C and you will get 12V 10000mah for $128
> (these are 3v cells as opposed to the normal 3.7v)

These are interesting, but their voltage falls off a lot with current
and temperature: Volts/cell = 2.2 (300 ma drain, 32 F); . That's only
8.8 volts with 4 cells in series, so you'd need at least 5 in series
just to get 11 volts.

But the size and weight are sure attractive (for four cells) compared to
a 12 volt, 5 ah SLA battery: about the same height and length, but less
than half the thickness, and 6 ounces vs 60! No wonder the model
airplane people like them!

There sure is a variation in output currents for similar amphours. This
unit

Saft Lithium LS26500 [C] 3.6V. 7700mAh

is limited to 10 ma!

--
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Eric Greenwell
Washington State
USA

[Bill Daniels]

What I wish for is a 14V, 12 AH Lithium-Polymer battery pack that comes with
a "snap-in" fixture. It would be nice to just snap in a freshly charged
battery just before a flight instead of fiddling with wires and battery
tie-downs or charging the battery in the glider. Maybe something that goes
in a 57mm instrument hole.

Bill Daniels

"Ken Kochanski (KK)" > wrote in message
oups.com...
> Although the technology is still pricy vs lead-acid batteries, the
> power/weight/size vs cost equation is getting better. Anybody using
> lithium model airplane packs bundeled to produce 12 - 14 v @3 - 6 amps
> as a power source for their glider? (I have been looking at the
> duralite site ... I'm sure there are others.)
> http://www.duralitebatteries.com/batteries.html
>
> KiloKilo
>

[WilLiscomb]

Lithium powered electric socks? www.cozywinters.com
williscomb

[[email protected]]

John Giddy > writes:

> If you use a well designed switching regulator which can boost as well
> as buck, the voltage supplied to the instruments can be maintained in
> the ideal range until the battery is almost completely flat, and at an
> average efficiency of about 80%.

With carefull design and construction, you can get over 95% efficient
converters running from a 12v source.

> AFAIK, complete discharge is not harmful to NiCd, Lithium types
> etc. It is harmful to lead acid batteries.

Full dischare of a NiCd *battery* is bad news, it is OK to fully
discharge a single cell on its own though. Lead acids can be run
totally flat, but must be put on charge imediatly or they
`sulphate'. Don't know about the various Li batteries.

--
Paul Repacholi 1 Crescent Rd.,
+61 (08) 9257-1001 Kalamunda.
West Australia 6076
comp.os.vms,- The Older, Grumpier Slashdot
Raw, Cooked or Well-done, it's all half baked.
EPIC, The Architecture of the future, always has been, always will be.

[tango4]

Nickel Metal Hydride packs also dislike being too deeply discharged. Apart
from that they offer a lot of the benefits - High density, high current,
low temperature operation of other modern batteries. Compared to lead acid
'gel cell' types they offer a reduction in mass of 50%.

My 9Ah 14.4volt NiMh battery is 2/3 the size of a standard 7 Ah 12v gell
cell and weighs 1/2 as much.

Ian

> wrote in message
...
> John Giddy > writes:
>
>> If you use a well designed switching regulator which can boost as well
>> as buck, the voltage supplied to the instruments can be maintained in
>> the ideal range until the battery is almost completely flat, and at an
>> average efficiency of about 80%.
>
> With carefull design and construction, you can get over 95% efficient
> converters running from a 12v source.
>
>> AFAIK, complete discharge is not harmful to NiCd, Lithium types
>> etc. It is harmful to lead acid batteries.
>
> Full dischare of a NiCd *battery* is bad news, it is OK to fully
> discharge a single cell on its own though. Lead acids can be run
> totally flat, but must be put on charge imediatly or they
> `sulphate'. Don't know about the various Li batteries.
>
> --
> Paul Repacholi 1 Crescent Rd.,
> +61 (08) 9257-1001 Kalamunda.
> West Australia 6076
> comp.os.vms,- The Older, Grumpier Slashdot
> Raw, Cooked or Well-done, it's all half baked.
> EPIC, The Architecture of the future, always has been, always will be.

[Jim Vincent]

>AIK, complete discharge is not harmful to NiCd, Lithium types
>> etc. It is harmful to lead acid batteries.

The latest designs of Lithium batteries accomodate larger discharge rates and
are becoming price efficient. But they will drop dead below a threshold level,
with no hope of salvage.

Lithium packs are designed in increments of 3.7V nominal per pack. Packs are
combined in series or in parallel to achieve desired voltage and amperage
levels.

In RC airplanes, we use a voltage cutoff device integrated with the speed
control (throttle). That cuttoff level is set at 3.0V per pack. When the
motor blips, you know the cutoff level is met and it is time to land. Go much
longer and the pack is dead.

I haven't used the Lithium batteries in cold weather yes. From what I've read
their performance does decline somewhat.

There is little risk of explosion with the latest versions of chargers and
batteries. As long as the pack is not abused, there is effectively zero chance
of fire or explosion.

I'm thinking about putting Lithium batteries in my sailplane but the price
point is not good yet on 12-14V, 7AH systems.



Jim Vincent
N483SZ

[Eric Greenwell]

tango4 wrote:
> Nickel Metal Hydride packs also dislike being too deeply discharged. Apart
> from that they offer a lot of the benefits - High density, high current,
> low temperature operation of other modern batteries. Compared to lead acid
> 'gel cell' types they offer a reduction in mass of 50%.
>
> My 9Ah 14.4volt NiMh battery is 2/3 the size of a standard 7 Ah 12v gell
> cell and weighs 1/2 as much.

I'm looking for ways to fit more AH into standard glider battery boxes,
so people can add a transponder without decreasing the battery run time
or going to the trouble of installing another battery box. For example,
going from a 7 AH battery to a 10 AH pack might achieve this,
particularly if it's a 14 volt pack instead of a 12 volt pack.

What battery (brand and part numbers, if you can) and charger do you
use, and where can we get them?

--
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Eric Greenwell
Washington State
USA

[Steve Hill]

I'm going to disagree with Jim Vincent on the use of Li-Poly batteries being
safe with current chargers...I have a charger specifically designed for use
on Li-poly batteries and each time I charge them I put the batteries
themselves into a Corningware container...I have had two sets of batteries
flat out spontaneously combust...they burn with a brilliant white hot light
that general estimates place in the vicinity of 2500 degrees.

My best friend was re-charing one set of his batteries and it lit on fire
and he didn't have it in a container and before he could put it out, it fell
from the table hit the floor and burned a hole all the way through the
wooden floor...As an avid R/C electric 3D nut, Li-Poly's are the ONLY way to
go, but their safety definitely leaves things to be desired.

I would NOT EVER....not for a second...reccomend putting one in a sailplane.



Steve Hill

[Tim Ward]

"Steve Hill" > wrote in message
...
> I'm going to disagree with Jim Vincent on the use of Li-Poly batteries
being
> safe with current chargers...I have a charger specifically designed for
use
> on Li-poly batteries and each time I charge them I put the batteries
> themselves into a Corningware container...I have had two sets of batteries
> flat out spontaneously combust...they burn with a brilliant white hot
light
> that general estimates place in the vicinity of 2500 degrees.
>
> My best friend was re-charing one set of his batteries and it lit on fire
> and he didn't have it in a container and before he could put it out, it
fell
> from the table hit the floor and burned a hole all the way through the
> wooden floor...As an avid R/C electric 3D nut, Li-Poly's are the ONLY way
to
> go, but their safety definitely leaves things to be desired.
>
> I would NOT EVER....not for a second...reccomend putting one in a
sailplane.
>
>
>
> Steve Hill

How fast was he charging it? That is, relative to its rated capacity in
Ampere Hours, how much current was he putting into it?

Tim Ward

[tango4]

"Eric Greenwell" > wrote in message
...
> tango4 wrote:
>> Nickel Metal Hydride packs also dislike being too deeply discharged.
>> Apart from that they offer a lot of the benefits - High density, high
>> current, low temperature operation of other modern batteries. Compared to
>> lead acid 'gel cell' types they offer a reduction in mass of 50%.
>>
>> My 9Ah 14.4volt NiMh battery is 2/3 the size of a standard 7 Ah 12v gell
>> cell and weighs 1/2 as much.
>
> I'm looking for ways to fit more AH into standard glider battery boxes, so
> people can add a transponder without decreasing the battery run time or
> going to the trouble of installing another battery box. For example, going
> from a 7 AH battery to a 10 AH pack might achieve this, particularly if
> it's a 14 volt pack instead of a 12 volt pack.
>
> What battery (brand and part numbers, if you can) and charger do you use,
> and where can we get them?
>
> --
> Change "netto" to "net" to email me directly
>
> Eric Greenwell
> Washington State
> USA

Hi Eric

I have the packs made up locally. They also supply me with a matched
microprocessor controlled charger. I am flying a Nimbus 3T with room for
both a 17ah Gell Cell ( right in the nose ) and a standard 7ah on the
cockpit floor behind the panel ( both standard schempp locations )

The replacement for the 17 ah is only 13 AH but is half the size and weight.
The replacement for the 7Ah is actually 9 AH but also only 1/2 the weight.
In practice the 9AH pack is delivering about 10 AH due to being better
suited to my current drain profile - about 750 mA continuous. ( Cost for the
9AH here in the UK was Batteries £79.50 each, Chargers £36.00 each They
are not cheap)

I had these packs made up as 12 cell packs. Nominally 14.4 volts but they
actually max out on full charge at about 16.5 volts - too much for Colibri
loggers and LX avionics. The voltage drops off to around 15 fairly quickly -
within 3/4 hour flying, and then tapers off to 14 volts for about 85% of the
profile. At 12 volts they are flat. In future I will have these made up as
11 Cell packs. This will keep the operating voltage to around 13 volts with
them going 'flat' at 10.5 and about 10 Ah. Still a lot better than the old
Gell Cell routine.

I have been using these batteries for a full season and their staying power
is impressive. I have an artificial horizon installed and even after a 5
hour flight there is plenty of go left to spin up the gyro without blacking
out radios, PDA or vario. Charging is simple , connect and go, 14 hour cycle
from flat to full. They could be recharged in as little as 2 hours but there
is little point in that and it does shorten expected lifecycles.

I expect at least 600 cycles out of the batteries and given that I only
charge the 9 Ah every 3 flights and the 17 hour once a month I reckon
they'll last as long as 10 or 15 years. By then we might all have little
fission devices or fuel cells installed anyway. That is of course if we have
any personal freedom left by then .......... sorry just a little cynical at
this time of the year.

I have a photo of the packs but your return eMail address bounces.

Ian

[Alex]

I've dealt quite a bit with lithium-ion and lithium-polymer batteries,
and I have to say that they are *extremely* sensitive to how they are
charged, discharged, and what temperature they operate at. If you're
planning on putting a Li-ion pack in your glider, make sure you do your
research and be very careful.

As far as voltage regulation goes, a switched DC-DC converter is the
way to go in terms of light weight and high electrical efficiency.
This is the least of your problems. The biggest problems with Li-ions
is looking after them during charging and discharging. Most Li-ion
cells operate at a nominal voltage of 3.7V. The voltage of the cells
*must* remain between 3.0V and 4.2V, and also within the stated
operating temperature range otherwise the cells are very likely to
out-gas, explode, catch fire, or all three.

Charging them is not a problem since, presumably, you would use an
off-the-shelf charger intended for Li-ion batteries. Discharging,
however, takes places in the glider -- in the air -- and will require
some kind of protection circuitry.

I have experience with these batteries through the solar car racing
community (a "sport" not too dissimilar to gliding!), and here is the
information on Li-ion batteries that is sent to teams:

http://www.americansolarchallenge.org/tech/resources/SAE_2001-01-0959.pdf
http://www.americansolarchallenge.org/tech/resources/lithiumcontrol.pdf

As stated in the above documents there are also further issues with
cell equalisation in battery packs consisting of more than one cell in
parallel. There's a lot to consider, and the consequences could be
fatal in a glider. You can always jump straight out of a solar car
without much damage to the car, but getting out of a glider is another
issue altogether...

Personally, I don't see the advantage of using Li-ion cells in gliders.
Model gliders/airplanes gain an advantage through longer run-time for
the same amount of weight. Full-size gliders don't really have an
issue with a few more pounds of weight that an extra Pb-acid battery
adds.

_Alex

[Eric Greenwell]

It's the concerns Alex lists that turned me away from Li cells for
glider use. Their main advantage appears to be light weight, and the few
pounds saving for an instrument battery is insignificant compared to the
problems.

It appears NiMh batteries are much more practical, for several reasons:

* similar voltage to SLA (sealed lead-acid) and Ni-Cd cells (1.2 volts -
10 cells makes a 12 volt battery)
* self-balancing of cells with charge rates similar to the SLA batteries
we use
* more capacity per cubic inch than SLA, NiCd, and Li (important if you
are trying to stuff more amphours into your battery box)
* charging at the 10 hour rate seems relatively safe, as long as it's
timer controlled.

THe problem I'm having is getting good data sheets on the 8 to 12
amphour cells. The sheets from major manufacturers like Sanyo and
Panasonic are very limited in their data, and the sheets from the
"off-brand" units, which are much cheaper, are even worse, or not
available at all.

Another problem is there are no 8+ amphour batteries available, so you'd
have make your own pack, or have one custom built. The units with
interesting capacities are not being pushed to consumers, but more to
OEMs. Plenty of AAA, AA, C and D cells and chargers available!

The cost is high, too, with a battery the physical size of a 12 volt, 7
amphour SLA (about $35) costing ~$150 just for the cells. Right now, it
seems using NiMh cells to extend your glider's capacity is for the
electrically knowledgeable person that really doesn't want to put in
another battery box.

I'm in contact with one pilot that is routinely using them, however. If
there are others, I'd like to hear from them, especially about replacing
12 volt, 7 amphour SLA batteries.


Alex wrote:

> I've dealt quite a bit with lithium-ion and lithium-polymer batteries,
> and I have to say that they are *extremely* sensitive to how they are
> charged, discharged, and what temperature they operate at. If you're
> planning on putting a Li-ion pack in your glider, make sure you do your
> research and be very careful.
>
> As far as voltage regulation goes, a switched DC-DC converter is the
> way to go in terms of light weight and high electrical efficiency.
> This is the least of your problems. The biggest problems with Li-ions
> is looking after them during charging and discharging. Most Li-ion
> cells operate at a nominal voltage of 3.7V. The voltage of the cells
> *must* remain between 3.0V and 4.2V, and also within the stated
> operating temperature range otherwise the cells are very likely to
> out-gas, explode, catch fire, or all three.
>
> Charging them is not a problem since, presumably, you would use an
> off-the-shelf charger intended for Li-ion batteries. Discharging,
> however, takes places in the glider -- in the air -- and will require
> some kind of protection circuitry.
>
> I have experience with these batteries through the solar car racing
> community (a "sport" not too dissimilar to gliding!), and here is the
> information on Li-ion batteries that is sent to teams:
>
> http://www.americansolarchallenge.org/tech/resources/SAE_2001-01-0959.pdf
> http://www.americansolarchallenge.org/tech/resources/lithiumcontrol.pdf
>
> As stated in the above documents there are also further issues with
> cell equalisation in battery packs consisting of more than one cell in
> parallel. There's a lot to consider, and the consequences could be
> fatal in a glider. You can always jump straight out of a solar car
> without much damage to the car, but getting out of a glider is another
> issue altogether...
>
> Personally, I don't see the advantage of using Li-ion cells in gliders.
> Model gliders/airplanes gain an advantage through longer run-time for
> the same amount of weight. Full-size gliders don't really have an
> issue with a few more pounds of weight that an extra Pb-acid battery
> adds.
>
> _Alex
>
>


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

Eric Greenwell
Washington State
USA