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What's all this Lithium Specific Battery Charger stuff anyh

 
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PostPosted: Tue Mar 14, 2023 2:10 pm    Post subject: What's all this Lithium Specific Battery Charger stuff anyh Reply with quote

All agreed Bob. Many years ago while on the phone with an EarthX tech trying to understand their prohibition against most smart chargers out there in frustration I asked him if it was safe to charge their batteries with my aircraft. Of course the answer was yes but a little further discussion convinced me that it's not the battery they are trying to protect, it's the BMS. Apparently their BMS can be damaged by the voltage pulses sent by "desulfating" chargers. That seems to be not a concern from your plot and the pictures which show that the "desulfating" mode is selectable, not automatic.

I was specifically asking about this charger you have let us know about because the description states (lithium batteries are not charged) which makes me wonder if the "smart" part of the charger could end seeing some behaviour of the lithium battery that it mistakes for a lead acid battery problem, and shutting off.
Recently a client of mine replaced a $400+ EarthX because "it goes dead". They dropped the offending one off and it was 0V. I left it hooked up to my power supply overnight at 14.5V and then tested it. It came out at 96% of new capacity (after 5 years, not bad). After checking the engine monitor data and asking a few questions the best theory we can come up with is that this perfectly good battery was replaced because they discharged it to BMS shutoff a few times and their "smart" charger assumed a problem and wouldn't charge it. So now they've spent $200 on a charger and have a spare battery.

On Tue, Mar 14, 2023 at 12:58 PM Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:

Quote:
At 12:24 PM 3/14/2023, you wrote:
Quote:
The NOCOs are way overpriced. Bob's example does a better job at 1/6th the price.

Bob, have you found a similar charger for lithium batteries?

  There are lithium and then there are LITHIUM batteries.
  I've oft pondered the contradictions in performance
  claims by the various purveyors of lithium products.

  There are dozens of batteries that are simple
  assemblies of cells stacked 4-high proposed
  for service in a 14v system. They claim
  to be drop-in replacements for wet or SVLA
  products.

  Okay, if the thing is claimed to live happily
  in a lead-acid environment, then what's
  this "special lithium charger" stuff all about?

  Then there are products that offer battery
  management systems within the battery itself.
  The term "BMS" does not offer an industry
  wide description of form and function.

  Products that seek to assure consumers of
  100% compatibility with the lead-acid world
  often include electronics adding substantially
  to the cost of the battery! Yet, there are as
  many (if not more) products offered with NO
  built in electronics. Some do offer a
  cell-balancing connector. Ebay and Amazon
  are replete with cell-balancing modules
  that cater to the DIY battery-array market.

  I'll call your attention to the figures here
  on my website:

https://tinyurl.com/mw4fz3pf

  One figure illustrates a family of capacity
  vs. charge voltage plots for an A123
  LiFePO4 cell. Note the battery performance
  when charged at various termination voltages
  ranging from 3.3 to 3.7 volts.  In a 4-stack
  array intended for 14v systems, these voltages
  correspond to system voltages of 13.2 to 14.8
  volts.

  Note that cell capacity is essentially maxed
  out with a charge voltage of 3.4 Volts/Cell
  (13.6V system) with no significant improvement
  above that.

  The other image is a snapshot of specs for
  a well known variety of LiFePO4 cells that
  state a max charging voltage of 4.2 until the
  current drops below 100mA. This would be a system
  voltage of 16.8 Volts!

  Perhaps this offers a reason for the success
  of the many bare-foot, 4-stack engine cranking
  products out there.  As long as system voltage
  is greater than 13.6 (but less than 16.Cool,
  the battery has a high order probability of
  a useful life.

  So, what's all this lithium specific charger
  stuff about? The charger we've been discussing
  in this thread tops out at just under 15V. No
  red flags there.

  In the BMS camp for lithium products, we're
  told that the battery is a plug-n-play replacement
  of the EXISTING wet or SVLA battery. Rest assured
  that the BMS will protect your substantial investment
  from alternator malfeasance . . . except that its
  not clear to me that the legacy lead-acid system
  set up to charge and 14.2 to 14.8 volts is something
  to be worried about.

  So that's a long introduction to my response to
  your question. Unless someone has DATA to suggest
  otherwise, I'm of the not-so-humble opinion that
  lithium specific chargers are in the same class
  as battery desulfators. There are dozens of patents
  on desulfation processes NONE of which are accompanied
  by repeatable laboratory grade tests that demonstrate
  efficacy of their claims.

  I've got a EarthX battery on the bench that's
  be maintained by one of my venerable BatteryMinders
  for about 10 years.  That reminds me, I think I'll
  run a new cap and load check on the little feller.
  Don't have an airplane to run it in but it's jump
  started a dozen or so vehicles over the years!

  The one thing I've not yet mentioned is the 'cell-
  balancing' feature suggested in some battery
  management philosophies.

  Cell balancing becomes a significant concern as
  the cells age. If the internal impedance and/or voltage
  vs. charge current one layer in the 4-stack array
  rises significantly over the others, it's capacity has
  been depressed. So while its brothers are still actively
  taking on more Joules of energy, the 'weak sister' is
  at risk for exacerbated damage due to over-charging.
  A cell balancing system places a dummy-load resistor
  across a compromised layer of cells to reduce the
  risks to the cells.

  Given what we've observed of the lithium art and
  science over the last decade, I'll suggest that cell
  balancing is probably not applicable to aircraft
  applications. Keep in mind that the majority market
  for batteries is populated with customers who routinely
  deep-discharge their batteries and flog 'em until they
  don't get up and hunt any more.

  We airplane guys are intently interested in
  CAPACITY of a battery compared against DESIGN
  GOALS for Plan-B endurance in battery only
  ops. The rule of thumb for battery replacement
  is to take it out of service at 80% of new
  or when battery-only endurance goals are not
  satisfied.

  In both SVLA and Lithium worlds, a battery is
  likely to still be cranking an engine when it's
  time to replace and before cell balancing becomes
  a significant issue.

  That's kind of a long winded answer to your
  question but hopefully gives you understanding
  that supports future decisions.




  Bob . . .

                   ////
                  (o o)
   ===========o00o=(_)=o00o=========
   < Go ahead, make my day . . .   >
   < show me where I'm wrong.      >
   =================================
 
   In the interest of creative evolution
   of the-best-we-know-how-to-do based
   on physics and good practice.



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skywagon185(at)gmail.com
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PostPosted: Mon Mar 20, 2023 11:24 am    Post subject: What's all this Lithium Specific Battery Charger stuff anyh Reply with quote

Hi Bob,

One aspect of lithium that is easily overlooked is the characteristic of its super low internal resistance (IR).
This gives it the ability to offer huge amounts of current if called for.
That is a huge advantage however that presents a problem sometimes.
If the battery is somewhat depleted, connected to a old style alternator system, when the engine is started it is usually operated at fairly low rpm's.  However, the battery due to its super low IR sits there saying "feed me all 60 amps" (or whatever the alternator set is rated) but it is barely above idle rpm.
Thus it is generating a ton of heat with not the normal cruise speed air blast available to cool it.
This problem really shows up in boats, RV's and such that have converted to Lithium.
The answer is using an active current limiter between the battery system and alternator to protect the alternator for overheating.....
D


On Tue, Mar 14, 2023 at 12:58 PM Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:

Quote:
At 12:24 PM 3/14/2023, you wrote:
Quote:
The NOCOs are way overpriced. Bob's example does a better job at 1/6th the price.

Bob, have you found a similar charger for lithium batteries?

  There are lithium and then there are LITHIUM batteries.
  I've oft pondered the contradictions in performance
  claims by the various purveyors of lithium products.

  There are dozens of batteries that are simple
  assemblies of cells stacked 4-high proposed
  for service in a 14v system. They claim
  to be drop-in replacements for wet or SVLA
  products.

  Okay, if the thing is claimed to live happily
  in a lead-acid environment, then what's
  this "special lithium charger" stuff all about?

  Then there are products that offer battery
  management systems within the battery itself.
  The term "BMS" does not offer an industry
  wide description of form and function.

  Products that seek to assure consumers of
  100% compatibility with the lead-acid world
  often include electronics adding substantially
  to the cost of the battery! Yet, there are as
  many (if not more) products offered with NO
  built in electronics. Some do offer a
  cell-balancing connector. Ebay and Amazon
  are replete with cell-balancing modules
  that cater to the DIY battery-array market.

  I'll call your attention to the figures here
  on my website:

https://tinyurl.com/mw4fz3pf

  One figure illustrates a family of capacity
  vs. charge voltage plots for an A123
  LiFePO4 cell. Note the battery performance
  when charged at various termination voltages
  ranging from 3.3 to 3.7 volts.  In a 4-stack
  array intended for 14v systems, these voltages
  correspond to system voltages of 13.2 to 14.8
  volts.

  Note that cell capacity is essentially maxed
  out with a charge voltage of 3.4 Volts/Cell
  (13.6V system) with no significant improvement
  above that.

  The other image is a snapshot of specs for
  a well known variety of LiFePO4 cells that
  state a max charging voltage of 4.2 until the
  current drops below 100mA. This would be a system
  voltage of 16.8 Volts!

  Perhaps this offers a reason for the success
  of the many bare-foot, 4-stack engine cranking
  products out there.  As long as system voltage
  is greater than 13.6 (but less than 16.Cool,
  the battery has a high order probability of
  a useful life.

  So, what's all this lithium specific charger
  stuff about? The charger we've been discussing
  in this thread tops out at just under 15V. No
  red flags there.

  In the BMS camp for lithium products, we're
  told that the battery is a plug-n-play replacement
  of the EXISTING wet or SVLA battery. Rest assured
  that the BMS will protect your substantial investment
  from alternator malfeasance . . . except that its
  not clear to me that the legacy lead-acid system
  set up to charge and 14.2 to 14.8 volts is something
  to be worried about.

  So that's a long introduction to my response to
  your question. Unless someone has DATA to suggest
  otherwise, I'm of the not-so-humble opinion that
  lithium specific chargers are in the same class
  as battery desulfators. There are dozens of patents
  on desulfation processes NONE of which are accompanied
  by repeatable laboratory grade tests that demonstrate
  efficacy of their claims.

  I've got a EarthX battery on the bench that's
  be maintained by one of my venerable BatteryMinders
  for about 10 years.  That reminds me, I think I'll
  run a new cap and load check on the little feller.
  Don't have an airplane to run it in but it's jump
  started a dozen or so vehicles over the years!

  The one thing I've not yet mentioned is the 'cell-
  balancing' feature suggested in some battery
  management philosophies.

  Cell balancing becomes a significant concern as
  the cells age. If the internal impedance and/or voltage
  vs. charge current one layer in the 4-stack array
  rises significantly over the others, it's capacity has
  been depressed. So while its brothers are still actively
  taking on more Joules of energy, the 'weak sister' is
  at risk for exacerbated damage due to over-charging.
  A cell balancing system places a dummy-load resistor
  across a compromised layer of cells to reduce the
  risks to the cells.

  Given what we've observed of the lithium art and
  science over the last decade, I'll suggest that cell
  balancing is probably not applicable to aircraft
  applications. Keep in mind that the majority market
  for batteries is populated with customers who routinely
  deep-discharge their batteries and flog 'em until they
  don't get up and hunt any more.

  We airplane guys are intently interested in
  CAPACITY of a battery compared against DESIGN
  GOALS for Plan-B endurance in battery only
  ops. The rule of thumb for battery replacement
  is to take it out of service at 80% of new
  or when battery-only endurance goals are not
  satisfied.

  In both SVLA and Lithium worlds, a battery is
  likely to still be cranking an engine when it's
  time to replace and before cell balancing becomes
  a significant issue.

  That's kind of a long winded answer to your
  question but hopefully gives you understanding
  that supports future decisions.




  Bob . . .

                   ////
                  (o o)
   ===========o00o=(_)=o00o=========
   < Go ahead, make my day . . .   >
   < show me where I'm wrong.      >
   =================================
 
   In the interest of creative evolution
   of the-best-we-know-how-to-do based
   on physics and good practice.



- 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
Back to top
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