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nuckolls.bob(at)aeroelect
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 Posted: Fri Jun 12, 2020 9:20 am Post subject: Speaking of LiFePo4 |
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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: 426
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| Posted: Fri Jun 12, 2020 12:09 pm Post subject: Speaking of LiFePo4 |
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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 . . .
|
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
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david(at)carter.net
Guest
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| Posted: Fri Jun 12, 2020 2:02 pm Post subject: Speaking of LiFePo4 |
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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)
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
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yellowduckduo(at)gmail.co
Guest
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| Posted: Fri Jun 12, 2020 2:14 pm Post subject: Speaking of LiFePo4 |
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|
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.
|
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
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| Back to top |
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cluros(at)gmail.com
Guest
|
| Posted: Fri Jun 12, 2020 2:43 pm Post subject: Speaking of LiFePo4 |
|
|
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 . . .
|
|
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
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lyleapgmc
Joined: 19 Feb 2014
Posts: 57
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| Posted: Fri Jun 12, 2020 2:51 pm Post subject: Speaking of LiFePo4 |
|
|
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 . . .
|
|
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
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m.whiting(at)frontier.com
Guest
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| Posted: Fri Jun 12, 2020 3:54 pm Post subject: Speaking of LiFePo4 |
|
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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.
|
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
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kenryan
Joined: 20 Oct 2009
Posts: 426
|
| Posted: Fri Jun 12, 2020 4:30 pm Post subject: Speaking of LiFePo4 |
|
|
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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