Matronics Email Lists :: View topic - Li-Ion Batteries for aircraft

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

Li-Ion Batteries for aircraft

Matronics Email Lists Forum Index -> AeroElectric-List

View previous topic :: View next topic

Author Message

nuckolls.bob(at)aeroelect
Guest

Posted: Mon Dec 22, 2008 2:28 pm Post subject: Li-Ion Batteries for aircraft

At 03:59 PM 12/22/2008, you wrote:

 	  Quote: 	
		  

<mjpereira68(at)gmail.com>



 >      On a related topic. Lots of folks are trying to figure

 >      out ways to integrate lithium-ion batteries into

 >      aircraft. It's no mean task. While the energy/weight

 >      radio of l-ion is seductive, it's sorta like figuring

 >      out a way to burn nitro-glycerine in your engine. Wow!

 >      What energy potential! Now, how do you integrate

 >      this potential into an existing, highly refined system

 >      in a way that does not increase risk?



Oh good lord, li-poly batteries are awesome for *model*

aviation. I hope the manufacturers you're alluding to are

considering the "A123 Systems" type chemistry batteries (which

will take abuse without emiting a napalm like lithium/cobalt

fog).


	


    Everybody with a product has a dog in this hunt. I'm aware

    of at least three serious efforts by folks who understand

    batteries and their role in aviation . . . and perhaps

    a dozen more wannabes.



    A friend of mine made this anecdotal observation about

    batteries in the numerous crashes he investigated: He

    said that if the airplane didn't burn after impact, more

    often than not, the battery was pitched out and could

    be found in the weeds. If the airplane did burn, more

    often than not, the battery was still in the airplane.



    While an exceedingly unscientific observation, it plays

    homage to the high energy density of these devices along

    with their willingness to dump that energy to the outside

    world without regard to the fondest desires of those

    individuals close by.



    Li-Ion batteries have the potential for being several

    times worse than their lead-acid or ni-cad cousins when

    it comes to undesirable energy spills!

        Bob . . .



        ----------------------------------------)

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

        ----------------------------------------

echristley(at)nc.rr.com
Guest

Posted: Tue Dec 23, 2008 7:04 am Post subject: Li-Ion Batteries for aircraft

Robert L. Nuckolls, III wrote:

 	  Quote: 	
		  

    A friend of mine made this anecdotal observation about

    batteries in the numerous crashes he investigated: He

    said that if the airplane didn't burn after impact, more

    often than not, the battery was pitched out and could

    be found in the weeds. If the airplane did burn, more

    often than not, the battery was still in the airplane.


	


We're way off topic right now, but...huh?

Are you saying that retaining the battery increases the chances of a 

fire?  The takeaway being that the battery isn't our friend during/after 

an accident?

nuckolls.bob(at)aeroelect
Guest

Posted: Wed Dec 24, 2008 1:39 am Post subject: Li-Ion Batteries for aircraft

At 09:02 AM 12/23/2008, you wrote:

 	  Quote: 	
		  

<echristley(at)nc.rr.com>



Robert L. Nuckolls, III wrote:

>

>    A friend of mine made this anecdotal observation about

>    batteries in the numerous crashes he investigated: He

>    said that if the airplane didn't burn after impact, more

>    often than not, the battery was pitched out and could

>    be found in the weeds. If the airplane did burn, more

>    often than not, the battery was still in the airplane.



We're way off topic right now, but...huh?


	


   How so? The discussion was about the extra-ordinary

   capabilities of Li-Ion batteries that make their

   acceptance into aircraft problematic. While their

   energy/weight ratios and exceedingly low source

   impedance make them electrically attractive, they're

   also famous throughout the family of Li-Ion products

   for spectacular and unpleasant failure modes from

   within.



   Even after these batteries are blessed by those who

   know-more-about-airplanes-than-we-do, there are still

   considerations for system integration which includes

   crash safety.



 	  Quote: 	
		  Are you saying that retaining the battery increases the chances of a fire?


	


   Doesn't that stand to reason? Fires need ignition sources

   and aluminum is not hard-sparking material. Hot engines are

   not even particularly strong ignition sources . . . but

   a battery capable of thousands of amps of fault current

   could probably be demonstrated to light off magnesium castings

   under the right conditions. Lighting off fuel spills is

   easy.



 	  Quote: 	
		     The takeaway being that the battery isn't our friend during/after 

 an accident?


	


   Would you not share that conclusion with me? Except for

   the chance that you might sit in the wreck and use the

   battery to power your radios for the purpose of calling

   for help, of what practical value is it? Once the airframe

   is compromised to the extent that the battery is subject to

   high current discharges, it's easy to assume that fuel

   tanks are equally compromised. All things considered, if

   I were on short-final to the rocks, being able to eject

   the battery is not an unattractive idea.

        Bob . . .



        ----------------------------------------)

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

        ----------------------------------------

echristley(at)nc.rr.com
Guest

Posted: Wed Dec 24, 2008 5:57 am Post subject: Li-Ion Batteries for aircraft

Robert L. Nuckolls, III wrote:

 	  Quote: 	
		     The takeaway being that the battery isn't our friend during/after an 

 accident?



   Would you not share that conclusion with me? Except for

   the chance that you might sit in the wreck and use the

   battery to power your radios for the purpose of calling

   for help, of what practical value is it? Once the airframe

   is compromised to the extent that the battery is subject to

   high current discharges, it's easy to assume that fuel

   tanks are equally compromised. All things considered, if

   I were on short-final to the rocks, being able to eject

   the battery is not an unattractive idea.



Oh, I agree.  It is just not something I've ever heard discussed, or 
	


even considered.  Now I'm wondering if there are any designs that 

provide for an battery eject?  Considering the logic behind your 

statement, the the crash investigator you referred to earlier, why 

aren't there more?

ceengland(at)bellsouth.ne
Guest

Posted: Wed Dec 24, 2008 6:33 am Post subject: Li-Ion Batteries for aircraft

Robert L. Nuckolls, III wrote:

 	  Quote: 	
		   

 <nuckolls.bob(at)aeroelectric.com>



 At 09:02 AM 12/23/2008, you wrote:

> 

> <echristley(at)nc.rr.com>

>

> Robert L. Nuckolls, III wrote:

>>

>>    A friend of mine made this anecdotal observation about

>>    batteries in the numerous crashes he investigated: He

>>    said that if the airplane didn't burn after impact, more

>>    often than not, the battery was pitched out and could

>>    be found in the weeds. If the airplane did burn, more

>>    often than not, the battery was still in the airplane.

>

> We're way off topic right now, but...huh?



   How so? The discussion was about the extra-ordinary

   capabilities of Li-Ion batteries that make their

   acceptance into aircraft problematic. While their

   energy/weight ratios and exceedingly low source

   impedance make them electrically attractive, they're

   also famous throughout the family of Li-Ion products

   for spectacular and unpleasant failure modes from

   within.



   Even after these batteries are blessed by those who

   know-more-about-airplanes-than-we-do, there are still

   considerations for system integration which includes

   crash safety.



> Are you saying that retaining the battery increases the chances of a 

> fire?



   Doesn't that stand to reason? Fires need ignition sources

   and aluminum is not hard-sparking material. Hot engines are

   not even particularly strong ignition sources . . . but

   a battery capable of thousands of amps of fault current

   could probably be demonstrated to light off magnesium castings

   under the right conditions. Lighting off fuel spills is

   easy.



>   The takeaway being that the battery isn't our friend during/after 

> an accident?



   Would you not share that conclusion with me? Except for

   the chance that you might sit in the wreck and use the

   battery to power your radios for the purpose of calling

   for help, of what practical value is it? Once the airframe

   is compromised to the extent that the battery is subject to

   high current discharges, it's easy to assume that fuel

   tanks are equally compromised. All things considered, if

   I were on short-final to the rocks, being able to eject

   the battery is not an unattractive idea.

        Bob . . . 


	


The 1st thing I thought about when reading the 'pitched battery=no fire' 

story is, wouldn't it be fairly simple to design a G-activated 

disconnect mounted directly to the battery? Basically the inverse of an 

ELT activator, to fail off instead of fail on. Something as simple as a 

spring- or mechanical fuse-loaded pivoting base for the battery that 

would allow the top to move forward, and bolt-on bullet or blade style 

connectors for the battery terminals that would face aft. With spring 

loaded insulators that would close if the connector halves separate, and 

the wires behind the battery and locked to structure, most any crash 

impact should try to move the battery forward, 'pulling the plugs' & 

allowing the insulators to close.



This wouldn't be the simplest project for a homebuilder, but should be 

relatively easy for an R&D department. Also, having been in a car wreck 

where the battery moved against the frame & was burning through the 

steel, there might even be an opportunity to make some money if it's 

marketed to auto regulators (never get it adopted voluntarily, of course).



Charlie

Terry Watson

Joined: 09 Jan 2006
Posts: 290
Location: Seattle, WA USA

Posted: Wed Dec 24, 2008 10:01 am Post subject: Li-Ion Batteries for aircraft

This is an interesting idea. It should be pretty simple in concept to design

an on-impact disconnect for a rear-mounted battery in an RV. Just allow the

battery to slide forward a few inches on impact, out of the slotted terminal

connectors mounted rigid enough to not follow the battery. RV wings have an

optional slotted mount at the leading edge to fuselage connection to allow

the wings to shear off. Someone smarter than me could probably come  up with

a scheme for a firewall mounted (forward of the firewall) battery too. The

battery would still be in the airplane, but not connected to any of the

wiring.



Terry

Stalled RV-8A project (too many bright ideas; not enough consistent effort)

Seattle



--

CBarber(at)TexasAttorney.
Guest

Posted: Wed Dec 24, 2008 11:32 am Post subject: Li-Ion Batteries for aircraft

Ok, not a productive comment, however, this discussion has me playing with 

the thought of hearing:



"Captain Picard, the matter/anti-matter containment is failing causing a 

reaction ark, she is about to blow!"



"Geordie, eject the core....NOW!"

Yeah, I am more of a NexGen guy then TOS.  To show what a geek I can be, the 

"N" number on my Velocity is N17010. <g>  Other Trek geeks will understand 

that.



Merry Christmas all.



All the best,



Chris Barber

Houston

---

nuckolls.bob(at)aeroelect
Guest

Posted: Wed Dec 24, 2008 12:24 pm Post subject: Li-Ion Batteries for aircraft

At 07:55 AM 12/24/2008, you wrote:

 	  Quote: 	
		  

<echristley(at)nc.rr.com>



Robert L. Nuckolls, III wrote:

>   The takeaway being that the battery isn't our friend 

> during/after an accident?

>

>   Would you not share that conclusion with me? Except for

>   the chance that you might sit in the wreck and use the

>   battery to power your radios for the purpose of calling

>   for help, of what practical value is it? Once the airframe

>   is compromised to the extent that the battery is subject to

>   high current discharges, it's easy to assume that fuel

>   tanks are equally compromised. All things considered, if

>   I were on short-final to the rocks, being able to eject

>   the battery is not an unattractive idea.

Oh, I agree.  It is just not something I've ever heard discussed, or 

even considered.  Now I'm wondering if there are any designs that 

provide for an battery eject?  Considering the logic behind your 

statement, the the crash investigator you referred to earlier, why 

aren't there more?


	


    When I asked the scattered-pieces/smoking-hole crowd at RAC

    to search their memories and archives for accidents where

    an electrical failure figured into the chain of events leading

    up to damage to aircraft/crew. They couldn't come up with

    one.(*) At the same time, there were electrical issues that

    caused tense moments and unplanned completions of flight.

    Bottom line is that a well considered architecture, plan-A/

    plan-B operating plan and reasonable training keeps even

    severe electrical failures from becoming a bad day in the

    cockpit. Given that OBAM aircraft are MUCH more forgiving

    than Barons and Jets, electrical failures in flight are

    even less risky.



    I don't think there was much interest in reducing the

    possibility of battery-induced, post-crash fire given that

    circumstances surrounding the cases where fire did occur

    were so severe that no useful difference in outcome would

    have been gained if the airplane had not caught fire.



Bob . . .

    (*) I've personally worked only two accidents in 30+ years

    that probably started with an electrical failure. One involved

    a King Air over the Swiss Alps that disappeared from radar

    and radio contact . . . BEFORE traversing the peaks.

    The airplane crashed into said peaks COMING THE OTHER WAY.



    The prevailing theory was that the avionics master relay

    failed and took down all the good stuff. The pilot decided

    to return sometime after crossing the peaks and for some

    reason, descended too early.



    The other was loss of both alternators in a piston twin

    flying in ice. Pilot made successful approach to landing

    looking out the foul weather window. He lost directional

    control on the runway resulting in loss of airframe and

    all souls aboard.

daveleikam(at)wi.rr.com
Guest

Posted: Wed Dec 24, 2008 11:36 pm Post subject: Li-Ion Batteries for aircraft

I would consider a dual wire high current plug similar to one used on my 

snowplow main power lead.  The plug supplies current to a motor similar to 

an engine starting motor which drives hydraulics to operate the plow.  The 

plug is very robust and under very harsh operating conditions has never 

unplugged itself during plowing operations.  The plug hangs freely between 

the front bumper of my truck and the plow.  However, with a good tug the 

plug separates to disconnect the wires to remove the plow unit from my 

truck.  This could be installed in the battery connection wires of the 

airplane and supported so as to disconnect in the event of excessive forward 

g forces.  The contact pins are also recessed in plastic so after 

disconnect, there would be no chance of contact with other metal if the 

battery terminals were also covered.  See 4b and 4c in the link below.



http://www.rustrepair.com/snow_plow_parts/onlinecat.htm?r=ds&p=sn-boss-bs.elec



Dave Leikam

RV-10 #40496

N89DA (Reserved)

Muskego, WI



---

hgerhardt

Joined: 18 Jul 2008
Posts: 3
Location: So Cal

Posted: Thu Dec 25, 2008 11:50 am Post subject: Re: Li-Ion Batteries for aircraft

[/quote]The 1st thing I thought about when reading the 'pitched battery=no fire' 

story is, wouldn't it be fairly simple to design a G-activated 

disconnect mounted directly to the battery? Charlie[/quote]



Delphi has already done this... it's a pyrotechnically activated battery cutoff switch.  See http://delphi.com/manufacturers/auto/ee/eec/bdsd/  In the cars they're installed in, the airbag module triggers it.  However, since we don't typically have airbag triggers on board, we could use the standard Ford fuel pump cutoff switch that Ford's been using since the mid-80's (it's a g-activated switch) See http://www.amazon.com/Standard-Motor-Products-Inertia-Switch/dp/B000C83MC8

Heinrich Gerhardt

RV-6, flying

Display posts from previous:

	Matronics Email Lists Forum Index -> AeroElectric-List	All times are GMT - 8 Hours
Page 1 of 1

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum