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ronaldcox

Joined: 24 Jan 2008
Posts: 41

Posted: Fri Nov 14, 2014 8:59 am Post subject: Lithium facts

I, forÂ one, haven't seen a boring thread here in a loooong time.Â  I'm learning a lot, and I think the activity indicates the same from others.Â  Doesn't have a direct application at the moment, but this is how NW ideas get developed within our community, and I hope no one is intimidated into killing off the discussion.



I'd suggest the complainer switch to the Digest, and then he can easily scroll to whatever he is interested in.

Ron



  [quote][b]

_________________
Ron Cox
Glasair Super II F/T
Under Construction at C77 - Still just about to fly!

jan_de_jong(at)casema.nl
Guest

Posted: Fri Nov 14, 2014 12:02 pm Post subject: lithium facts

LiFePO4 or LFP, not Lipo (= LiCoO2 or LCO ). There is a big     difference in safety:

     http://batteryuniversity.com/learn/article/types_of_lithium_ion

     

     Jan de Jong

     

     On 11/14/2014 5:41 PM, Jeff Luckey       wrote:

     

     [quote]                Jan,

         

           

         I don't think I'm being pessimistic; cautious             is a better word.  

           

         

           

         I have witnessed several lipo fires or their             aftermath in R/C aircraft.  I even remember a Toyota Corolla             that burned to the tires because of a Lipo that was being             charged in the back seat.

         

         

         In addition, we all know about the Boeing issues. How           many dollars did they spend on R&D?

         

         

         I think it would be unwise to ignore the possibility           of a Lipo fire.  

         

         

         

         Based on my experience over the past 10 years with           Lipos, I would not even consider flying behind one - it is           simply not worth it to me to save a few pounds.

         

         

         Having said that - Lipos are great for driving around           in your Tesla - if there's problem, you can get out and walk -           but I don't want to be at 7500 ft when that happens.

         

         

         

         

         -Jeff

           

         

           

         

           

         

           

         

                                                  On Friday,                   November 14, 2014 8:08 AM, Jan de Jong                   <jan_de_jong(at)casema.nl> (jan_de_jong(at)casema.nl) wrote:

                  

               

               

                                                    On 11/14/2014 4:27 AM, Jeff Luckey wrote:

                      	  Quote: 	
		                                                  Suggest updating the weight                             calculations to include a steel battery box                             to contain a lipo fire.  

                           

                         

                       

                     	
                     

                     Is this a little pessimistic?

                     

                     Some old LiFePO4 on youtube, for those who have not                     looked there yet -

                     vandalism committed upon a Headway 38120 10Ah                     LiFePO4 cell:

                     

                     http://www.youtube.com/watch?v=8IBapfB0Imo

                     http://www.youtube.com/watch?v=52h8IK0IdqI

                     http://www.youtube.com/watch?v=wkJM8MZkFKU

                     

                     Are the results valid for  A123 ANR26650M1-B cells?                     

                     

                     - on the one hand the Headway cell has a lower                     maximum discharge rate (10C vs. 30C)

                     - and is slightly (8% or so) heavier per Ah

                     

                     - on the other hand the state of charge ranges from                     fully charged to very much overcharged

                     

                     It does not appear as if a fire must be expected in                     the course of reasonable or even unreasonable use.

                     

                     Jan de Jong

                      	  Quote: 	
		  



	
     [b]

BobsV35B(at)aol.com
Guest

Posted: Fri Nov 14, 2014 12:35 pm Post subject: lithium facts

Good Afternoon Jeff, 

  

 And, if we stopped talking about lithium batteries, where would you post  your reservations?

  

 Personally. I think the more written about them, the better. You will  notice that Boeing is still using the units as are most cell phones and other  small electronic devices.

  

 Happy Skies,

  

 Old Bob

  

  In a message dated 11/14/2014 2:26:19 P.M. Central Standard Time,  jluckey(at)pacbell.net writes:

  	  Quote: 	
		        Jan,

   



   I    don't think I'm being pessimistic; cautious is a better word.     



   



   I    have witnessed several lipo fires or their aftermath in R/C aircraft.  I    even remember a Toyota Corolla that burned to the tires because of a Lipo that    was being charged in the back seat.

   



   In    addition, we all know about the Boeing issues. How many dollars did they spend    on R&D?

   



   I    think it would be unwise to ignore the possibility of a Lipo fire.     



   



   Based    on my experience over the past 10 years with Lipos, I would not even consider    flying behind one - it is simply not worth it to me to save a few  pounds.

   



   Having    said that - Lipos are great for driving around in your Tesla - if there's    problem, you can get out and walk - but I don't want to be at 7500 ft when    that happens.

   



   



   -Jeff



   



   

	


 [quote][b]

nuckolls.bob(at)aeroelect
Guest

Posted: Fri Nov 14, 2014 1:34 pm Post subject: lithium facts

At 21:27 2014-11-13, you wrote:

 	  Quote: 	
		  Suggest updating the weight calculations to include a steel battery 

box to contain a lipo fire.



-Jeff


	


   Haven't really prayed over the fire issue much. We

   know that the True Blue enclosure was designed, tested

   and qualified to contain the worst that a

   catastrophic energy release can offer. At same

   time, we know that to test the enclosure, the BMS

   has to be bypassed and the battery abused with

   a 42 volt charger and only after some considerable

   time do cells begin to fail. Then they exude a mixture

   of flammable gasses . . . which do not 'burn' for lack

   of oxygen. The mixture is vented harmlessly over-board

   while surface temperatures on the battery enclosure

   remain quite modest.



   In this case, the energetic mayhem going on within

   the battery box isn't really a fire but simply an

   array of cells in self-destruction . . . after one or

   more cells is abused to failure thus triggering

   a cascade.



   This kind of testing is the sort of thing the

   Navy's Battery labs in Crane, IN used to do.

   I suspect they still do. Assume the worst even

   if you have to trigger the event yourself . . .

   then mitigate the outcome.



   Obviously, many segments of the battery market

   are embracing lithium products not the least of

   which is motorcycles. There are many more

   lithium batteries in service outside OBAM

   aviation than inside it. The marketplace is

   a huge laboratory for testing the general

   robustness of available products. I've seen

   anecdotal references to 'fires' with

   lithium batteries on motorcycles. A couple were

   attributed failure of a "mechanical" voltage

   regulator to properly charge the battery.

   Another spoke a wiring issue (it may have

   be the battery wires burning . . . not the

   battery).



   Given the legacy aviation philosophy for

   watching bus voltage and automatically

   reacting to overvoltage conditions - combined

   design limits that automatically 'soft-charge'

   to 50% of chemical capacity, it seems

   that the likelihood of an electrically

   induced battery event is very low.



   I think it unlikely that flame-proof battery

   boxes will ever get a warm reception

   in light aviation . . . at least not until

   the "market laboratory" raises perceptions of

   risk to higher levels of apprehension.



   The really cool thing is that there are few

   imperatives for making the lead->lithium

   switch. Our airplanes will continue to fly

   as they have for over 100 years. There is

   both time and increasing opportunity to build

   a well deserved confidence in the new

   technology.

   Bob . . .

argoldman(at)aol.com
Guest

Posted: Fri Nov 14, 2014 5:08 pm Post subject: lithium facts

Again, remember that there are several types of Li batteries each with it's own safety record. If we are talking safety of Li batteries and are only consideringt LIFePo4 then it is only appropriate that we refer only to the safety record of this type of battery.

 

  Except for Cessna and Boeing, both of which, I believe used the cobalt variety, I am unaware of any type other than LiFePo4 as suggested for our aircraft. What the auto makers and computer/cell phone makers are using is probably different.

 

 Rich

    

  

     

  

     

  

    --

jan_de_jong(at)casema.nl
Guest

Posted: Sat Nov 15, 2014 11:49 am Post subject: lithium facts

Bob,



In case you are starting to consider EarthX for our airplanes.....

I had some interaction with Reg Nicoson, lead product engineer at 

EarthX, a little over a year ago concerning unwanted buit-in OV cut-off 

which ended with the following last and second-to-last message:



"

Tricky - there is voltage level, but there is also risetime.

Alternator OV relay is slow at say 15.0 V.

Battery OV mosfets are fast at say 16.0 V.

A fast step from 14.5 to 18 volts would give a 50 ms dropout or so.

Which can possibly be covered with a large capacitor across the bus.

It does get somewhat involved though.



Jan



On 10/1/2013 6:58 AM, Sales wrote:

You are correct, a BMS is required for safe and reliable operation.   The

lithium cell high voltage cutoff has to be below 4volt per cell, or 16V for

the battery.   Our high voltage cutoff is set to 15.5 volt, which is where

the mosfets start to turn off, but they don't completely turn off until

16.5V at the battery terminal (15.8volt at the lithium cells).



Is it possible to adjust your aircrafts OV protection setting to 15 - 

15.5V?

If so I believe it would work.



Reg

"



I wonder if you would want to try and induce EartX to make an aviation 

version of their batteries that don't have the buit-in OV cutoff, 

replacing it with a stern warning that an external reliable fast OV 

switch is mandatory. They could even sell one.



Jan de Jong

davevon

Joined: 02 Jan 2015
Posts: 3
Location: Florida

Posted: Mon Jan 05, 2015 8:07 am Post subject: Re: lithium facts

Hi All,



Hope I'm not too late to join in on the discussion, I wish I would have seen this sooner.  Greg over at B&C pointed me in this direction.



I'm in process of redoing the complete electrical system in a Laser 230 aerobatic airplane.  The system had evolved into something that was very heavy, unsafe and just plain wrong in so many ways...



To save weight I bought an Aerovoltz/Ballistic LiFePo4 EVO2-16 battery.  I'm using a B&C SD-8 with their external regulator and OV protection.



Researching charging voltages for the LiFePo4 chemistry I'm finding a large variation in recommendations.



The EV (Electric Vehicle) guys claim 3.33v/cell is 100% charged and shouldn't be taken beyond that.  http://www.diyelectriccar.com/forums/showthread.php/you-all-destroying-your-lifepo4-cells-65336.html



Then I've seen a couple of places saying 3.65v/cell is 100% charged with a max voltage of 4.2v.  http://www.powerstream.com/LLLF.htm



The stock B&C system charges at 14.4v and the OV protection is set 16v.  Ballistic batteries is telling me to charge at 14.4v but don't go over or "bad things will happen".  I'm sure that the OV protection has to be set more than even a .1v higher that the regulated voltage to prevent nuance trips.



I'm guessing that there's some variation between cell manufactures and their voltage specs and add to that the battery manufactures/assemblers add their safety margin which leads to a case like the Aerovoltz/Ballistic having no leeway between the charging voltage and do not go over voltage...



So is there a definitive answer???



Thank you for your time,



Dave

richard.beebe(at)yale.edu
Guest

Posted: Mon Jan 05, 2015 10:29 am Post subject: lithium facts

On 01/05/2015 11:07 AM, davevon wrote:

 	  Quote: 	
		   

 <davevon(at)bellsouth.net>



 > [...]
	


 	  Quote: 	
		   Researching charging voltages for the LiFePo4 chemistry I'm finding a

 large variation in recommendations.



 The EV (Electric Vehicle) guys claim 3.33v/cell is 100% charged and

 shouldn't be taken beyond that.



  Then I've seen a couple of places saying 3.65v/cell is 100% charged

 with a max voltage of 4.2v.


	


I have an EV that I converted with LiFePo4 cells. While charging I 

charge until the voltage hits 3.5v per cell (and I've heard that 3.65 is 

the highest safe range but there's little added beyond 3.5v). I then 

hold the voltage until the current drops to 0.05C.



After I stop charging the voltage will drop to somewhere around 

3.2-3.3v. So maybe that's what the first voltage is about.



 	  Quote: 	
		    The stock B&C system charges at 14.4v and the OV protection is set

 16v.  Ballistic batteries is telling me to charge at 14.4v but don't

 go over or "bad things will happen".  I'm sure that the OV protection

 has to be set more than even a .1v higher that the regulated voltage

 to prevent nuance trips.


	


Since they're building batteries to replace lead-acid cells, its pretty 

silly of them not to protect their batteries from "normal" lead-acid 

voltages. If they have 4 cells, 14.4v is 3.6 per cell which should be 

fine. The maximum of 4.2 x 4 = 16.8 so bad things shouldn't happen with 

an occasional foray above 14.4 except perhaps shortening the life of the 

battery.



 	  Quote: 	
		   I'm guessing that there's some variation between cell manufactures

 and their voltage specs and add to that the battery

 manufactures/assemblers add their safety margin which leads to a case

 like the Aerovoltz/Ballistic having no leeway between the charging

 voltage and do not go over voltage...



 So is there a definitive answer???


	


I've found that there's quite a variation in knowledge about LiFePo4 

cells among the people who are selling them and even among those 

building them.



--Rick

nuckolls.bob(at)aeroelect
Guest

Posted: Mon Jan 05, 2015 3:46 pm Post subject: lithium facts

 	  Quote: 	
		    	  Quote: 	
		  So is there a definitive answer??? 	


 I've found that there's quite a variation in knowledge about LiFePo4 cells among the people who are selling them and even among those building them. 	


    Gee . . . what was your first clue?



    I've been sifting the lithium pile of sand for about 4 months.

    I'll be writing an article for KitPlanes on some of my findings.



    In brief, I believe I am on solid ground with the following

    assertions:



    LiFePo4 IS the chemistry of choice



    The MAX charge voltage for LiFePo4 is 4.2 volts per

    cell.



    Sift through the spec sheets for commercial offerings

    of LiFePo4 and you'll find MOST cells "rated" at 3.7V

    charge, 3.3V nominal delivery point.



    Here are some exemplar performance curves one particular

    cell



 

   [img]cid:.0[/img]



    Note that charging at 4.2 volts nearly DOUBLES the cell's contained

    energy. Stack 4 cells in series to perform in a 14v system and

    you would have to charge the battery at 16.8 volts. A tad high for

    many 14V bus operated devices . . . and perhaps out of reach for

    many voltage regulators.



    It's a little different ball game for consumer products that discharge

    lithium cells with switchmode power supplies. You can order chargers

    rated for EITHER 3.7 or 4.2 volts per cell. There are no caveats

    offered for the use of these chargers with any of the COTS lithium

    products . . .hence, no big risk . . . but a substantial difference

    in cell performance.



    3.7 x 4 is 14.8 volts . . . right in the ball park for plug-n-play

    replacement of SLVA with Lithium. Yes, STORED energy is 1/2 but service

    life gets a real boost . . . and risk for electrically induced damage

    to the battery goes way down. The AeroVoltz 3x4 array I tested clocked

    in at just over 7AH capacity when charged on a 14.5V bus.



    Cells promoted in the wild are burdened with some outrageous

    claims for capacity . . . John Q. Public has few tools or skills

    to determine if his purchase was righteous or not . . . so the flim-flammers

    get away with it. MOST of the cells I've sampled off eBay were not

    worth the postage to get them onto my workbench . . . however,

    some are quite good.



    Balancing chargers are another story . . . but the bottom line is

    that the COTS offerings of lithium drop-ins for  SVLA battery

    boxes don't come with a lot of hazard to anything but your

    pocketbook. As the lithium market matures, we may well be

    speaking of 16 volt systems for future airplanes.



 

   Bob . . .

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davevon

Joined: 02 Jan 2015
Posts: 3
Location: Florida

Posted: Tue Jan 06, 2015 8:21 am Post subject: Re: lithium facts

Thanks to those who responded!  I'm going to carry on with a plug-n-play setup.



Does anyone have more of a back story of what took place with this fire?  I'm assuming poor voltage regulation or a short?  It took place a while back and there hasn't been much discussion on it.



http://www.heavenboundaviation.com/documents/AerovoltzbatteryfirePDF.pdf



Thanks,



Dave

rlborger(at)mac.com
Guest

Posted: Tue Jan 06, 2015 9:15 am Post subject: lithium facts

Dave,



That’s an interesting LiFePo story, because that chemistry is supposed to be fire safe.



Maybe poor voltage regulation, but probably a short inside or outside the battery.  



Ugly result that could have been a heck of a lot uglier if he hadn’t put it on the ground when he did.



Blue skies & tailwinds,

Bob Borger

Europa XS Tri, Rotax 914, Airmaster C/S Prop (75 hrs).

Little Toot Sport Biplane, Lycoming Thunderbolt AEIO-320 EXP

3705 Lynchburg Dr.

Corinth, TX  76208-5331

Cel: 817-992-1117

rlborger(at)mac.com

On Jan 6, 2015, at 10:21 AM, davevon <davevon(at)bellsouth.net> wrote:






Thanks to those who responded!  I'm going to carry on with a plug-n-play setup.



Does anyone have more of a back story of what took place with this fire?  I'm assuming poor voltage regulation or a short?  It took place a while back and there hasn't been much discussion on it.



http://www.heavenboundaviation.com/documents/AerovoltzbatteryfirePDF.pdf



Thanks,



Dave

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Jan 06, 2015 9:59 am Post subject: lithium facts

At 10:21 2015-01-06, you wrote:

 	  Quote: 	
		  



Thanks to those who responded!  I'm going to carry on with a 

plug-n-play setup.



Does anyone have more of a back story of what took place with this 

fire?  I'm assuming poor voltage regulation or a short?  It took 

place a while back and there hasn't been much discussion on it.



http://www.heavenboundaviation.com/documents/AerovoltzbatteryfirePDF.pdf


	


   Thanks for the heads-up on this . . . you guys offer a wider

   spectrum of eyes-n-ears than I can muster on my own. I'll

   see if I can find out more about this incident.



   Bob . . .

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Jan 06, 2015 10:07 am Post subject: lithium facts

At 11:13 2015-01-06, you wrote:

 	  Quote: 	
		  



Dave,



That's an interesting LiFePo story, because that chemistry is 

supposed to be fire safe.



Maybe poor voltage regulation, but probably a short inside or 

outside the battery.



Ugly result that could have been a heck of a lot uglier if he hadn't 

put it on the ground when he did.


	


    Unfortunately, the carcass will probably not be

    closely examined. The actual burning may have been

    limited to plastic in the case but initiated by

    a catastrophic fault within the battery.



    Unless the 'event' involves a TC aircraft, personal

    injury or serious loss of airframe, the NTSB won't have

    much interest in spending $thousands$ to deduce root

    cause . . . and AeroVoltz is probably not going to

    pursue a microscopic examination either.



    This happened a long time ago. I'll write AeroVoltz

    to see what they have to contribute to understanding.



    Given the smaller/lighter characteristics of the

    LiPo batteries, it's probably not a serious weight

    hit to consider stainless boxes with fire-resistant

    linings or some such . . . it may be that some approach

    similar to the True Blue Power packaging improves

    the FMEA.



   Bob . . .

richard.beebe(at)yale.edu
Guest

Posted: Tue Jan 06, 2015 12:02 pm Post subject: lithium facts

Fire-safer but not fire safe. The older Lithium Cobalt will start to

break down--and perhaps enter thermal runaway--at around 160C. These are

the ones that gave lithium its bad rep. LiFoPo4 doesn't start to break

down until around 300C. That said I don't think these cells entered

thermal runaway. I suspect maybe one of the cells developed an internal

short and either it got hot or--because they were receiving too much

voltage without that one cell in play--the others did. Then the plastic

case melted and caught on fire. If the cells were actually on fire it's

not likely that him dribbling his water bottle on it would have put the

fire out.



So my question to AeroVoltz would be what the case is made of and are 

they using the same plastic now?



--Rick



On 01/06/2015 12:13 PM, Robert Borger wrote:

 	  Quote: 	
		   

 <rlborger(at)mac.com>



 Dave,



 That’s an interesting LiFePo story, because that chemistry is

 supposed to be fire safe.



 Maybe poor voltage regulation, but probably a short inside or outside

 the battery.



 Ugly result that could have been a heck of a lot uglier if he hadn’t

 put it on the ground when he did.



 Blue skies & tailwinds, Bob Borger Europa XS Tri, Rotax 914,

 Airmaster C/S Prop (75 hrs). Little Toot Sport Biplane, Lycoming

 Thunderbolt AEIO-320 EXP 3705 Lynchburg Dr. Corinth, TX  76208-5331

 Cel: 817-992-1117 rlborger(at)mac.com

 On Jan 6, 2015, at 10:21 AM, davevon <davevon(at)bellsouth.net> wrote:



 

 <davevon(at)bellsouth.net>



 Thanks to those who responded!  I'm going to carry on with a

 plug-n-play setup.



 Does anyone have more of a back story of what took place with this

 fire?  I'm assuming poor voltage regulation or a short?  It took

 place a while back and there hasn't been much discussion on it.

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Jan 06, 2015 1:47 pm Post subject: lithium facts

 	  Quote: 	
		  So my question to AeroVoltz would be what the case is made of and 

are they using the same plastic now?


	


   Agreed . . . good put . . .



   Bob . . .

davevon

Joined: 02 Jan 2015
Posts: 3
Location: Florida

Posted: Tue Jan 06, 2015 3:41 pm Post subject: Re: lithium facts

I think the Aerovoltz and Ballistic batteries may be the same with different covers (different logo is all).



Ballistic:

http://www.ballisticparts.com/product_info.php?cPath=141&products_id=428



Aerovoltz:

http://www.aerovoltz.com/av16.html



Dave

nuckolls.bob(at)aeroelect
Guest

Posted: Thu Jan 08, 2015 8:27 am Post subject: lithium facts

At 17:41 2015-01-06, you wrote:

 	  Quote: 	
		  



I think the Aerovoltz and Ballistic batteries may be the same with 

different covers (different logo is all).



Ballistic:

http://www.ballisticparts.com/product_info.php?cPath=141&products_id=428



Aerovoltz:

http://www.aerovoltz.com/av16.html



Dave


	


   Seems probable . . . I've read somewhere that AeroVoltz

   is housed in ABS plastic . . . not exactly renowned for

   a resistance to combustion.



   Bob . . .

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