AviationBanter - View Single Post

**[email protected]**

On Fri, 22 Mar 2013 08:05:23 -0600, Daryl
wrote:

On 3/22/2013 6:09 AM, Keith W wrote:
Daryl wrote:
On 3/22/2013 3:23 AM, Keith W wrote:
Daryl wrote:
On 3/22/2013 12:55 AM, Mr. B1ack wrote:
On Fri, 22 Mar 2013 03:00:07 +0000 (UTC), (Bradley K.
Sherman) wrote:

Who are you gonna believe, Boeing or your own lying eyes?

Boeing Co. (BA)'s assertion that U.S. investigators ruled
out a fire within the battery case of a Japan Airlines Co.
(9201) 787 is premature, a National Transportation Safety
Board spokesman said.

Investigators examining the Jan. 7 fire aboard the
Dreamliner in Boston haven't ruled out that flames erupted
within the lithium-ion battery container, Peter Knudson
said today in response to questions about the issue.
...
Michael Sinnett, Boeing's chief project engineer, said in
the briefing that investigators hadn't found evidence of
flames within the Boston battery's container box, an
indication it worked as designed to limit damage from a
battery failure.

A witness who tried to fight the Jan. 7 fire said he saw 3-
inch (7.6-centimeter) flames outside the lithium-ion
battery, and the NTSB has found evidence of high
temperatures within battery cells that failed, according to
preliminary safety-board documents released March 7.
...
http://www.businessweek.com/news/2013-03-15/ntsb-contradicts-boeing-claim-of-no-fire-in-787-battery

--bks

Gawd ... is THIS thread still going on ???????????/

Yes, the 787 is a failure.

Put it this way ... after hearing about its problems *I* will
NEVER fly on one - ever.

And I'm hardly the only one who feels this way.

Not interested in burning to death over the Pacific ....

The conventional Batteries are sometimes called Sealed Lead Acid
Batteries but they are actually AGM batteries.

Modern passenger aircraft normally use Nickel Cadmium batteries

Which are prone to a lot of problems. And it's old tech. Now for the
real negatives. If you overcharge them, they overheat. If you let
them go down below 20% they will need to be taken out and charged
very, very slowly with a special charger. They are very susceptible
to temperature ranges. They are the heaviest of the Non Lead Acid
batteries, their life span is almost equal to the sealed lead acid if
you don't count the fact they damage easy. The cost is more than the
AGM.
The AGM is just now finding it's way into the aircraft industry. Of
course, it has been somewhat over looked because of the Lithiums. But
it appears that small aircraft that are worried about initial building
costs are not overlooking them.

What they are looking at is the replacement hours on the Lithiums. They
start out at 800 charges and go to 2000 charges depending on the
type of Lithium. The weights in comparison to the AGM is anywhere 3
times to 5 times lighter. But the cost is at least 5 times the cost.

Less time between
replacements, requires a heated and cooled area but is the most
dependable. If that is all that is keeping the 787 from flying,
it's a pretty simple fix.

Not necessarily as that may need recertification which is a complex
and lengthy since the batteries would be heavier and take up more
space.

They are going to have to be re certified anyway. The AGM isn't that
much larger and it's pretty well proven in the Electric Vehicles to
day.

Most electrical vehicles do not use AGM's, their energy density is
too low as is their charge rate

examples
Toyota Prius - NiMH batteries
Nissan Leaf - Lithium ion batteries
Chevvy Volt - Lithium ion batteries
Tesla - Lithium ion batteries
Fisker - Lithium ion batteries
VW Electric - Lithium ion batteries
Renault - Lithium ion batteries

Battery energy density MJ per kilogram

Lithium-ion battery 0.720
Alkaline battery 0.671
Nickel-metal 0.28
Lead-acid battery 0.17

The reason the AGM isn't used in larger applications is that it cannot
be recharged as it is being discharged. You left out a slew that use
Deep Cells.

IT does the job if you keep it over 50% just like clockwork and
can last at least 2 to 5 years without going below 50% charge if you
keep them above freezing and below 100 degrees (the same as the
Lithiums). I use AGMs on a daily basis and my battery provider says
I am the hardest on batteries he's ever seen. I am getting ready to
do another build that uses the heavier Deep Cell which is designed to
put up with my punishement. But the AGMs are more rugged than the
Lithiums that I also use.

Nacads also work but for about one run into town before they overheat.
Ever seen a Nacad blow up? IT's pretty anticlimatic. They burst and
make a mess out of everything around it. And it's caustic. Same goes
for a Lithium except they will go into flame and feed the flame until
all the liquid is used up. I have never had a case break open on an
AGM. I've crashed em, dump em, drop em, used them for Rocky Mountain
Offroad, and more.

I can see that the Deep Cell Sealed Lead Acid should be as tough and
have a longer run time but they are twice as heavy.

Which is something of a problem for aircraft

Just leave out that 1 six pack of Tomato Juice to make up the
difference. It's not a real problem where an extra 10 pounds is really
going to make a difference for something the size of the 787. An added
10 pounds for safety sake is very important.

But it is a LOT more than 10 lbs!!!!!

The lifespan of
the Deep Cell the way I use batteries should be as high as the
Lithium and cost less. But the weight means only my 3 wheelers will
use them. They just don't make 10 to 15 amp deep cells. But they do
make a very solid 35 amp at twice the weight and size of a 12 amp AGM.

I am just not sold on Lithiums and I am certainly not sold on Nicads.
The Airline Aircraft Industry can use the AGMS and have less problems,
almost the same run time as the lower Lithium Mag batteries and save a
bunch of money.

Airbus use NiCads ,the Boeing 737, 747 (pre-800) and 777 use NiCads , they
disagree
with you.

Nicads are old technology. The AGM batter is much newer. When they
were designing the 737, 747 and 777 the AGMs weren't available. Single
Airplanes use the AGMs and that is more critical for weight and safety
than the big birds are.

I use all these batteries in transporation every day. I am a dealer in
the AGMs and the Lithiums as well as the motors and kits. I can also
get you a good deal in Deep Cells but the shipping would be a killer. I
used to handle Nicads but their output amps were just too low for any of
the transport applications. They would get hot and burn out the
controller after only a few miles of operation.

I'll say it again, after a decade of actually using these batteries,
using nicads is too problematic to depend on for safety. And the LiCo
battery they used has yet to have an application in transportation
because it's just too prone to problems as well. Unlike the Nicad that
just gets hot or ruptures with no fire, the LiCo battery bursts into a
very nasty bonfire. The safest and most dependable battery for them is
still the AGM.

Daryl