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Is lithium ion battery technology still not there?

R

Richard Henry

Jan 1, 1970
0
I do not exactly agree with inherently dangerous.  I say inherently
difficult (to damn difficult) to do safely.  See sodium-sulphur batteries.
?-)

Arre yo proposing that sodium-sulfur batteries are not inherently
dangerous?
 
L

legg

Jan 1, 1970
0

Protection mechanisms don't need no steenkeen printed circuit board.

A simply polymer layer, placed in the end seal, can swell to
disconnect the exposed end terminal from the battery proper, if
overheated. This is a common physical feature of many types of
rechargeable 'dumb' batteries.

Not really popular, because imprecise and tending to disconnect with
age/accumulated hours/ambient exposure.

Neither (pcb or polymer) protects against internal-fault-generated
heat.

RL
 
S

SoothSayer

Jan 1, 1970
0
What's the difference, besides playing lawyer with words? If you have masses of
two substances that react energetically and exothermically, densely packaged in
the same volume, with a deliberately thin separator, expect trouble.

The ideal battery would keep the reactive components separated. A fuel cell, or
its liquid equivalent, would keep the reactants in separate tanks and only pipe
in what's needed into the reaction space. Something like zinc-air admits one
reactant from outside.

Primary batteries tend to be safer than rechargables. I wonder if airplanes
could use primary batteries.

Seems like bad economics to ground a fleet of roughly $200 million planes to
save about 1000 pounds per.


About 25 years ago or so, the US Navy came up with Hydrogen fuel cells.
Not like what we have now, IIRC. They were essentially a gas cylinder
with Hydrogen gas in it under pressure, and when fully charged it was
like 90 psi, and it dropped in pressure as it discharged. Do not know
what the energy density or construction was, and they would likely be
pretty heavy unless they used Aluminum cylinders/chambers.

They were certainly a rechargeable design. Don't know if such a thing
would be a suitable replacement. Hydrogen is flammable. It would have
to be purged in an emergency circumstance.
 
About 25 years ago or so, the US Navy came up with Hydrogen fuel cells.
Not like what we have now, IIRC. They were essentially a gas cylinder
with Hydrogen gas in it under pressure, and when fully charged it was
like 90 psi, and it dropped in pressure as it discharged. Do not know
what the energy density or construction was, and they would likely be
pretty heavy unless they used Aluminum cylinders/chambers.

They were certainly a rechargeable design.

Fuel cells are *not* "rechargeable", in the battery sense.
Don't know if such a thing
would be a suitable replacement. Hydrogen is flammable. It would have
to be purged in an emergency circumstance.

That would be a pretty dumb design since these batteries' whole
purpose in life are emergency circumstances.
 
S

Sylvia Else

Jan 1, 1970
0
On Sat, 23 Feb 2013 20:21:45 -0800, josephkk <[email protected]>

Seems like bad economics to ground a fleet of roughly $200 million planes to
save about 1000 pounds per.

Though that was never the intent. If they had a certificated and
functional substitute that could be installed now to get the aircraft
back into the air, no doubt they'd do it, even if the battery weighed
1000 pounds more. But, of course, they don't have one.

Sylvia.
 
M

Martin Brown

Jan 1, 1970
0
I do not exactly agree with inherently dangerous. I say inherently
difficult (to damn difficult) to do safely. See sodium-sulphur batteries.
?-)

I am with John on this one.

Sodium sulphur batteries have been going to be the next great thing
since the 1980's. I knew someone who worked on them - they were lethal!

High energy density *is* inherently dangerous - and even more so when
both components of the stored chemical energy are kept inside the same
physical space as in a battery. Lithium cells are particularly volatile
and are well known to have caused trouble in consumer laptops.

Even petrol (US gas) which is an everyday consumer item is very much
more dangerous than the average member of the public can grasp. This
leads to very sad accidents when people do silly things with it.
 
Y

Yzordderrex

Jan 1, 1970
0
I am with John on this one.



Sodium sulphur batteries have been going to be the next great thing

since the 1980's. I knew someone who worked on them - they were lethal!



High energy density *is* inherently dangerous - and even more so when

both components of the stored chemical energy are kept inside the same

physical space as in a battery. Lithium cells are particularly volatile

and are well known to have caused trouble in consumer laptops.



Even petrol (US gas) which is an everyday consumer item is very much

more dangerous than the average member of the public can grasp. This

leads to very sad accidents when people do silly things with it.



--

Regards,

Martin Brown

Whatever happened to the carbon-sulphur-potassium nitrate battery? I'm sure that would be a magnitude safer than the cobalt based unit my buddies are putting together back in Tucson.
 
S

Sylvia Else

Jan 1, 1970
0
Whatever happened to the carbon-sulphur-potassium nitrate battery?

Too much damage to the connected equipment due to excessive power output
variation.

Sylvia.
 
S

Sylvia Else

Jan 1, 1970
0
You mean like in gasoline and jet fuel?

The latter do at least require a supply of oxygen before anything
untoward can happen, whereas a battery has everything in place to start
emitting heat if some internal fault occurs.

An ideal battery chemistry would self-limit its power output when it
warms up so that it cannot suffer thermal runaway.

Sylvia.
 
U

Uwe Hercksen

Jan 1, 1970
0
John said:
If they don't have a parallel plan running for NiCads or something, they are
betting big time.

Hello,

NiCads with the same energy stored would be heavier and larger than
those lithium cells used before. A reconstruction of the battery
compartment and the airplane structure around this compartment may be
necessary.

Bye
 
M

Martin Brown

Jan 1, 1970
0
If they don't have a parallel plan running for NiCads or something, they are
betting big time.

I think you mean past tense "were" betting big time and cocked it up.

Though the failure mode appears to have been a combo of bad wiring
harness and inability of the battery unit to protect itself from bad
external connections coupled with the volatile lithium cell chemistry.

Given that laptop and phone makers already knew enough to put defensive
failsafe protection into these batteries it seems astonishing that
aerospace designers on a civilian plane did not. It isn't like lithium
cells have a glowing reputation for reliability and robustness either.

http://www.electronicsweekly.com/bl...2007/09/whats-wrong-with-lithiumion-ba-1.html

There have been plenty of serious recalls of kit with dodgy lithium
batteries where inadequate protection could lead to self immolation!
 
J

josephkk

Jan 1, 1970
0
Arre yo proposing that sodium-sulfur batteries are not inherently
dangerous?

I am proposing they are inherently damn difficult to do safely. It is a
similar concept.

?-)
 
J

josephkk

Jan 1, 1970
0
What's the difference, besides playing lawyer with words? If you have masses of
two substances that react energetically and exothermically, densely packaged in
the same volume, with a deliberately thin separator, expect trouble.

The ideal battery would keep the reactive components separated. A fuel cell, or
its liquid equivalent, would keep the reactants in separate tanks and only pipe
in what's needed into the reaction space. Something like zinc-air admitsone
reactant from outside.

Primary batteries tend to be safer than rechargables. I wonder if airplanes
could use primary batteries.

Seems like bad economics to ground a fleet of roughly $200 million planes to
save about 1000 pounds per.

I think you have half of a good point with the zinc-air batteries. Good
energy density, indefinite shelf life, but one use only. Given the use
involved that might not be inappropriate. OTOH at 38,000 feet the air is
rather a bit thinner, and the gradient on the way down is noticeable.
Designing a zinc-air battery for the required performance with that change
in conditions may be very challenging, of course you could add bottled air
at altitude, but that carries other problems with it.

?-)
 
J

Jasen Betts

Jan 1, 1970
0
I think you have half of a good point with the zinc-air batteries. Good
energy density, indefinite shelf life, but one use only. Given the use
involved that might not be inappropriate. OTOH at 38,000 feet the air is
rather a bit thinner, and the gradient on the way down is noticeable.
Designing a zinc-air battery for the required performance with that change
in conditions may be very challenging, of course you could add bottled air
at altitude, but that carries other problems with it.

use bleed air from the jet engines, same as is used for cabin pressure.
 
exc ept if you are trying a mid-air restart and need the APU run up to

achieve it, you won't have bleed air available.

They have an air-driven turbine generator they deploy below the fuselage to provide even more backup. They even had to use it once in test flights when they had a massive console fire in the cock pit.
 
U

Uwe Hercksen

Jan 1, 1970
0
Martin said:
Given that laptop and phone makers already knew enough to put defensive
failsafe protection into these batteries it seems astonishing that
aerospace designers on a civilian plane did not. It isn't like lithium
cells have a glowing reputation for reliability and robustness either.

Hello,

there is an important difference. If something goes wrong with the
lithium cells in a laptop or phone, it is acceptable to do an emergency
shut off of the device.
If the lithium cells in a plane overheat, emergency power must be
maintained, you cant switch of the cells. Emergency power from these
cells must be available until a save landing has been done. The only
alternative is to switch to a second or third set of cells.

Bye
 
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