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Speaking of LiFePo4

 
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nuckolls.bob(at)aeroelect
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PostPosted: Fri Jun 12, 2020 9:20 am    Post subject: Speaking of LiFePo4 Reply with quote

At 04:33 PM 6/11/2020, you wrote:
Quote:
--> AeroElectric-List message posted by: Jan de Jong <jan_de_jong(at)casema.nl>

Dear all,

Better not confuse LiPo with LiFePO4 (also called LFP). Important differences.
A search with both terms will lead to some clarity I expect.

An very important point. Not all 'lithium' cells
are the same. While the energy density is
higher for chemistries other than lithium
iron phosphate (LiFePo4), the relative
robustness and safety of the LiFePo4
devices has prompted a chemistry of choice
decision for most suppliers to our craft . . .
indeed most consumer motive power applications.

For our purposes, when ever I refer to
a lithium product, know that I'm referring
to the LiFePo4 technology.

Speaking of LiFePo4:

I observe that virtually all the COTS lithium
chargers in my stable, every one 'tops off'
at 4.2 volts. These chargers were used to
explore qualities of a bevy of 18650
cells laying around the shop. I've
attached a plot for a constellation
of cells. A plot of the as-found condition
of a cell was followed by a plot of a
recharged condition.

Most of the 'weak' cells showed marked
recovery . . . others did not. One interesting
feature of this exercise is to note the
starting voltage for the discharge plot
of each recharged cell.

Virtually all produced first delivery of
energy at 4.0 volts or more. Hmmm . . .
It seems this was related to charging
top-off voltage. Okay, if one wishes
to maximize exploitation of your ship'
lithium battery, do you want to raise
your alternator voltage to 4 x 4.2 =
16.8 volts?

Hmmm . . . most of our electro whizzies
probably wouldn't mind . . . but if you're
carrying incandescent lights of any size,
service life would be reduced by 50% or more . . .
but they would certainly be bright!

I've posted an article found on powerstream.com

See: https://tinyurl.com/yazw9jnh

By the way, check out the rest of this website.
It's a treasure trove of data on DC power
systems. I had the name of the author at
one time but let it get lost. If anyone
perusing this resource runs across the author's
name, I'd appreciate a heads-up.

The article illustrates some interesting numbers
on LiFePo4 performance. First, there is
little value in charging the LiFePo4 cell
at it rated maximum. The writer demonstrates
that charging at considerably lower levels
does not significantly affect stored energy
until charge-per-cell voltage drops below
3.40. Okay, 3.40 x 4 is 13.6 volts. I
think we can live with that!

In fact, we're told that the charge-discharge
service life of lithium cells is improved
by operating the cells between 30 and 90%
of the chemical capacity of the cell. Okay
operating the contemporary 4-cell array
products at the legacy 14.2 to 14.4 volts
(3.6 volts per cell) wont give up significant
performance while extending service life.

I'm going to repeat the experiment in the
article cited. I will add features
that explore system integration questions
going to what may prove to be the 'next
generation' of OBAM aviation electrical system
architectures.


Bob . . .


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kenryan



Joined: 20 Oct 2009
Posts: 424

PostPosted: Fri Jun 12, 2020 12:09 pm    Post subject: Speaking of LiFePo4 Reply with quote

Okay, 20 minutes with google reveals plenty of examples of COTS chargers, but no definition of COTS. Could someone please educate me on this terminology? Thanks.

On Fri, Jun 12, 2020 at 9:27 AM Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:

Quote:
At 04:33 PM 6/11/2020, you wrote:
Quote:
--> AeroElectric-List message posted by: Jan de Jong <jan_de_jong(at)casema.nl (jan_de_jong(at)casema.nl)>

Dear all,

Better not confuse LiPo with LiFePO4 (also called LFP). Important differences.
A search with both terms will lead to some clarity I expect.

  An very important point. Not all 'lithium' cells
  are the same. While the energy density is
  higher for chemistries other than lithium
  iron phosphate (LiFePo4), the relative
  robustness and safety of the LiFePo4
  devices has prompted a chemistry of choice
  decision for most suppliers to our craft . . .
  indeed most consumer motive power applications.

  For our purposes, when ever I refer to
  a lithium product, know that I'm referring
  to the LiFePo4 technology.

  Speaking of LiFePo4:

  I observe that virtually all the COTS lithium
  chargers in my stable, every one 'tops off'
  at 4.2 volts. These chargers were used to
  explore qualities of a bevy of 18650
  cells laying around the shop. I've
  attached a plot for a constellation
  of cells. A plot of the as-found condition
  of a cell was followed by a plot of a
  recharged condition.

  Most of the 'weak' cells showed marked
  recovery . . . others did not. One interesting
  feature of this exercise is to note the
  starting voltage for the discharge plot
  of each recharged cell.

  Virtually all produced first delivery of
  energy at 4.0 volts or more.  Hmmm . . .
  It seems this was related to charging
  top-off voltage. Okay, if one wishes
  to maximize exploitation of your ship'
  lithium battery, do you want to raise
  your alternator voltage to 4 x 4.2 =
  16.8 volts?

  Hmmm . . . most of our electro whizzies
  probably wouldn't mind . . . but if you're
  carrying incandescent lights of any size,
  service life would be reduced by 50% or more . . .
  but they would certainly be bright!

  I've posted an article found on powerstream.com

  See:  https://tinyurl.com/yazw9jnh

  By the way, check out the rest of this website.
  It's a treasure trove of data on DC power
  systems. I had the name of the author at
  one time but let it get lost. If anyone
  perusing this resource runs across the author's
  name, I'd appreciate a heads-up.
 
  The article illustrates some interesting numbers
  on LiFePo4 performance. First, there is
  little value in charging the LiFePo4 cell
  at it rated maximum. The writer demonstrates
  that charging at considerably lower levels
  does not significantly affect stored energy
  until charge-per-cell voltage drops below
  3.40.  Okay, 3.40 x 4 is 13.6 volts. I
  think we can live with that!

  In fact, we're told that the charge-discharge
  service life of lithium cells is improved
  by operating the cells between 30 and 90%
  of the chemical capacity of the cell. Okay
  operating the contemporary 4-cell array
  products at the legacy 14.2 to 14.4 volts
  (3.6 volts per cell) wont give up significant
  performance while extending service life.

  I'm going to repeat the experiment in the
  article cited. I will add features
  that explore system integration questions
  going to what may prove to be the 'next
  generation' of OBAM aviation electrical system
  architectures.


  Bob . . .


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david(at)carter.net
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PostPosted: Fri Jun 12, 2020 2:02 pm    Post subject: Speaking of LiFePo4 Reply with quote

Commercial-of-the-shelf. Often used in the government contracting world & the opposite of bespoke.  
On Fri, Jun 12, 2020 at 4:12 PM Ken Ryan <keninalaska(at)gmail.com (keninalaska(at)gmail.com)> wrote:

Quote:
Okay, 20 minutes with google reveals plenty of examples of COTS chargers, but no definition of COTS. Could someone please educate me on this terminology? Thanks.

On Fri, Jun 12, 2020 at 9:27 AM Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:

Quote:
At 04:33 PM 6/11/2020, you wrote:
Quote:
--> AeroElectric-List message posted by: Jan de Jong <jan_de_jong(at)casema.nl (jan_de_jong(at)casema.nl)>

Dear all,

Better not confuse LiPo with LiFePO4 (also called LFP). Important differences.
A search with both terms will lead to some clarity I expect.

  An very important point. Not all 'lithium' cells
  are the same. While the energy density is
  higher for chemistries other than lithium
  iron phosphate (LiFePo4), the relative
  robustness and safety of the LiFePo4
  devices has prompted a chemistry of choice
  decision for most suppliers to our craft . . .
  indeed most consumer motive power applications.

  For our purposes, when ever I refer to
  a lithium product, know that I'm referring
  to the LiFePo4 technology.

  Speaking of LiFePo4:

  I observe that virtually all the COTS lithium
  chargers in my stable, every one 'tops off'
  at 4.2 volts. These chargers were used to
  explore qualities of a bevy of 18650
  cells laying around the shop. I've
  attached a plot for a constellation
  of cells. A plot of the as-found condition
  of a cell was followed by a plot of a
  recharged condition.

  Most of the 'weak' cells showed marked
  recovery . . . others did not. One interesting
  feature of this exercise is to note the
  starting voltage for the discharge plot
  of each recharged cell.

  Virtually all produced first delivery of
  energy at 4.0 volts or more.  Hmmm . . .
  It seems this was related to charging
  top-off voltage. Okay, if one wishes
  to maximize exploitation of your ship'
  lithium battery, do you want to raise
  your alternator voltage to 4 x 4.2 =
  16.8 volts?

  Hmmm . . . most of our electro whizzies
  probably wouldn't mind . . . but if you're
  carrying incandescent lights of any size,
  service life would be reduced by 50% or more . . .
  but they would certainly be bright!

  I've posted an article found on powerstream.com

  See:  https://tinyurl.com/yazw9jnh

  By the way, check out the rest of this website.
  It's a treasure trove of data on DC power
  systems. I had the name of the author at
  one time but let it get lost. If anyone
  perusing this resource runs across the author's
  name, I'd appreciate a heads-up.
 
  The article illustrates some interesting numbers
  on LiFePo4 performance. First, there is
  little value in charging the LiFePo4 cell
  at it rated maximum. The writer demonstrates
  that charging at considerably lower levels
  does not significantly affect stored energy
  until charge-per-cell voltage drops below
  3.40.  Okay, 3.40 x 4 is 13.6 volts. I
  think we can live with that!

  In fact, we're told that the charge-discharge
  service life of lithium cells is improved
  by operating the cells between 30 and 90%
  of the chemical capacity of the cell. Okay
  operating the contemporary 4-cell array
  products at the legacy 14.2 to 14.4 volts
  (3.6 volts per cell) wont give up significant
  performance while extending service life.

  I'm going to repeat the experiment in the
  article cited. I will add features
  that explore system integration questions
  going to what may prove to be the 'next
  generation' of OBAM aviation electrical system
  architectures.


  Bob . . .



--
---
David Carter
david(at)carter.net (david(at)carter.net)


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yellowduckduo(at)gmail.co
Guest





PostPosted: Fri Jun 12, 2020 2:14 pm    Post subject: Speaking of LiFePo4 Reply with quote

Commercial Off The Shelf rather than custom made

On 12/06/2020 3:45 PM, Ken Ryan wrote:
Quote:
Okay, 20 minutes with google reveals plenty of examples of COTS
chargers, but no definition of COTS. Could someone please educate me
on this terminology? Thanks.


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cluros(at)gmail.com
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PostPosted: Fri Jun 12, 2020 2:43 pm    Post subject: Speaking of LiFePo4 Reply with quote

Commercial Of The Shelf.

In other words purchaseable.
On Fri, Jun 12, 2020, 13:14 Ken Ryan <keninalaska(at)gmail.com (keninalaska(at)gmail.com)> wrote:

Quote:
Okay, 20 minutes with google reveals plenty of examples of COTS chargers, but no definition of COTS. Could someone please educate me on this terminology? Thanks.

On Fri, Jun 12, 2020 at 9:27 AM Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:

Quote:
At 04:33 PM 6/11/2020, you wrote:
Quote:
--> AeroElectric-List message posted by: Jan de Jong <jan_de_jong(at)casema.nl (jan_de_jong(at)casema.nl)>

Dear all,

Better not confuse LiPo with LiFePO4 (also called LFP). Important differences.
A search with both terms will lead to some clarity I expect.

  An very important point. Not all 'lithium' cells
  are the same. While the energy density is
  higher for chemistries other than lithium
  iron phosphate (LiFePo4), the relative
  robustness and safety of the LiFePo4
  devices has prompted a chemistry of choice
  decision for most suppliers to our craft . . .
  indeed most consumer motive power applications.

  For our purposes, when ever I refer to
  a lithium product, know that I'm referring
  to the LiFePo4 technology.

  Speaking of LiFePo4:

  I observe that virtually all the COTS lithium
  chargers in my stable, every one 'tops off'
  at 4.2 volts. These chargers were used to
  explore qualities of a bevy of 18650
  cells laying around the shop. I've
  attached a plot for a constellation
  of cells. A plot of the as-found condition
  of a cell was followed by a plot of a
  recharged condition.

  Most of the 'weak' cells showed marked
  recovery . . . others did not. One interesting
  feature of this exercise is to note the
  starting voltage for the discharge plot
  of each recharged cell.

  Virtually all produced first delivery of
  energy at 4.0 volts or more.  Hmmm . . .
  It seems this was related to charging
  top-off voltage. Okay, if one wishes
  to maximize exploitation of your ship'
  lithium battery, do you want to raise
  your alternator voltage to 4 x 4.2 =
  16.8 volts?

  Hmmm . . . most of our electro whizzies
  probably wouldn't mind . . . but if you're
  carrying incandescent lights of any size,
  service life would be reduced by 50% or more . . .
  but they would certainly be bright!

  I've posted an article found on powerstream.com

  See:  https://tinyurl.com/yazw9jnh

  By the way, check out the rest of this website.
  It's a treasure trove of data on DC power
  systems. I had the name of the author at
  one time but let it get lost. If anyone
  perusing this resource runs across the author's
  name, I'd appreciate a heads-up.
 
  The article illustrates some interesting numbers
  on LiFePo4 performance. First, there is
  little value in charging the LiFePo4 cell
  at it rated maximum. The writer demonstrates
  that charging at considerably lower levels
  does not significantly affect stored energy
  until charge-per-cell voltage drops below
  3.40.  Okay, 3.40 x 4 is 13.6 volts. I
  think we can live with that!

  In fact, we're told that the charge-discharge
  service life of lithium cells is improved
  by operating the cells between 30 and 90%
  of the chemical capacity of the cell. Okay
  operating the contemporary 4-cell array
  products at the legacy 14.2 to 14.4 volts
  (3.6 volts per cell) wont give up significant
  performance while extending service life.

  I'm going to repeat the experiment in the
  article cited. I will add features
  that explore system integration questions
  going to what may prove to be the 'next
  generation' of OBAM aviation electrical system
  architectures.


  Bob . . .



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lyleapgmc



Joined: 19 Feb 2014
Posts: 57

PostPosted: Fri Jun 12, 2020 2:51 pm    Post subject: Speaking of LiFePo4 Reply with quote

COTS  is what you slept on in the military.

On 6/12/2020 2:45 PM, Ken Ryan wrote:

Quote:
Okay, 20 minutes with google reveals plenty of examples of COTS chargers, but no definition of COTS. Could someone please educate me on this terminology? Thanks.



On Fri, Jun 12, 2020 at 9:27 AM Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:

Quote:
At 04:33 PM 6/11/2020, you wrote:
Quote:
--> AeroElectric-List message posted by: Jan de Jong <jan_de_jong(at)casema.nl (jan_de_jong(at)casema.nl)>

Dear all,

Better not confuse LiPo with LiFePO4 (also called LFP). Important differences.
A search with both terms will lead to some clarity I expect.

  An very important point. Not all 'lithium' cells
  are the same. While the energy density is
  higher for chemistries other than lithium
  iron phosphate (LiFePo4), the relative
  robustness and safety of the LiFePo4
  devices has prompted a chemistry of choice
  decision for most suppliers to our craft . . .
  indeed most consumer motive power applications.

  For our purposes, when ever I refer to
  a lithium product, know that I'm referring
  to the LiFePo4 technology.

  Speaking of LiFePo4:

  I observe that virtually all the COTS lithium
  chargers in my stable, every one 'tops off'
  at 4.2 volts. These chargers were used to
  explore qualities of a bevy of 18650
  cells laying around the shop. I've
  attached a plot for a constellation
  of cells. A plot of the as-found condition
  of a cell was followed by a plot of a
  recharged condition.

  Most of the 'weak' cells showed marked
  recovery . . . others did not. One interesting
  feature of this exercise is to note the
  starting voltage for the discharge plot
  of each recharged cell.

  Virtually all produced first delivery of
  energy at 4.0 volts or more.  Hmmm . . .
  It seems this was related to charging
  top-off voltage. Okay, if one wishes
  to maximize exploitation of your ship'
  lithium battery, do you want to raise
  your alternator voltage to 4 x 4.2 =
  16.8 volts?

  Hmmm . . . most of our electro whizzies
  probably wouldn't mind . . . but if you're
  carrying incandescent lights of any size,
  service life would be reduced by 50% or more . . .
  but they would certainly be bright!

  I've posted an article found on powerstream.com

  See:  https://tinyurl.com/yazw9jnh

  By the way, check out the rest of this website.
  It's a treasure trove of data on DC power
  systems. I had the name of the author at
  one time but let it get lost. If anyone
  perusing this resource runs across the author's
  name, I'd appreciate a heads-up.
 
  The article illustrates some interesting numbers
  on LiFePo4 performance. First, there is
  little value in charging the LiFePo4 cell
  at it rated maximum. The writer demonstrates
  that charging at considerably lower levels
  does not significantly affect stored energy
  until charge-per-cell voltage drops below
  3.40.  Okay, 3.40 x 4 is 13.6 volts. I
  think we can live with that!

  In fact, we're told that the charge-discharge
  service life of lithium cells is improved
  by operating the cells between 30 and 90%
  of the chemical capacity of the cell. Okay
  operating the contemporary 4-cell array
  products at the legacy 14.2 to 14.4 volts
  (3.6 volts per cell) wont give up significant
  performance while extending service life.

  I'm going to repeat the experiment in the
  article cited. I will add features
  that explore system integration questions
  going to what may prove to be the 'next
  generation' of OBAM aviation electrical system
  architectures.


  Bob . . .



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m.whiting(at)frontier.com
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PostPosted: Fri Jun 12, 2020 3:54 pm    Post subject: Speaking of LiFePo4 Reply with quote

Commercial Off The Shelf

Sent from my iPad

Quote:
On Jun 12, 2020, at 6:25 PM, Ken Ryan <keninalaska(at)gmail.com> wrote:

Okay, 20 minutes with google reveals plenty of examples of COTS chargers, but no definition of COTS. Could someone please educate me on this terminology? Thanks.
Quote:




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kenryan



Joined: 20 Oct 2009
Posts: 424

PostPosted: Fri Jun 12, 2020 4:30 pm    Post subject: Speaking of LiFePo4 Reply with quote

Thanks!

On Fri, Jun 12, 2020 at 2:21 PM C&K <yellowduckduo(at)gmail.com (yellowduckduo(at)gmail.com)> wrote:

Quote:
--> AeroElectric-List message posted by: C&K <yellowduckduo(at)gmail.com (yellowduckduo(at)gmail.com)>

Commercial Off The Shelf rather than custom made

On 12/06/2020 3:45 PM, Ken Ryan wrote:
> Okay, 20 minutes with google reveals plenty of examples of COTS
> chargers, but no definition of COTS. Could someone please educate me
> on this terminology? Thanks.
>
>

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