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 |  | Lithium Ion BatteriesA search of the
    web 2021-12 ref. Lithium Ion Batteries, especially for recovery
    of over discharged batteries, & what risks in recharging,
    & what charge current for 18650 cells.External Links
      
        General, Not Specific To Deep Discharge Recovery
          
            Battery Manufacturer Product Specific
            Non Battery Manufacturer - Users &
            Researchers
        Deep discharge recovery
          
            Forum"Mechanism of the entire overdischarge process and
          overdischarge-induced internal short circuit in
          lithium-ion batteries"www
          . nature . com / articles / srep30248
Overdischarge and Aging Analytics of Li-Ion Cells -
          Journal of The Electrochemical Society - PDFiopscience . iop . org / article / 10.1149 / 1945-7111 /
          aba00a
          www . einhell . de / en - de / blog / workshop / battery
          - guide . html"Our Power X-Change chargers are equipped with a
          refresh mode. If a battery is plugged into the charger
          whose deep discharge is not yet too far advanced, the
          battery can still be "saved" in many cases. The charger
          charges the battery very carefully until the minimum
          charge level is reached again. It can then be charged
          again as normal."
Deep Discharge research PDF on requestwww . researchgate . net / publication / 311499287_Li -
          Ion_Battery_Deep_Discharge_Degradation
          maker . pro / custom / tutorial / what - is - deep -
          discharge - build - a - simple - circuit - to - protect -
          batteries"when the battery undergoes over-discharging, it is
          very difficult to recharge it because the internal
          resistance of the cell has increased ... example of a
          widely used 4.2V Li-Po battery when the voltage reached
          below 3.7V there is damage in the internal resistance of
          the battery. The damage becomes significant below 3.0V.
          Charging these batteries take tons of time. For charging,
          a smart charger is a mandatory requirement. Initially,
          for 0-3V of the battery, charge at 1/20 C charge rate. Do
          not leave the battery unattended and also touch it
          frequently and check if it's not getting hot. If so,
          lower the charge rate. When the battery is charged at
          3.0V, increase the charge rate to 1/10 C rate and after
          3.7V, you can charge it at higher 1/2C rate until
          4.2V"
How to Revive Lithium Ion Batteriessciencing . com / revive - lithium - ion - batteries -
          5982537.html
 you shouldn't attempt it with batteries that have
          been below 1.5 V for over a week ... Return the battery
          into the lithium-ion charger and give it a full charge,
          which should take around 3 hours depending on what type
          of Li-ion battery you are reconditioning. Some chargers
          automatically progress from recovery mode to charging, so
          on these devices you can just leave the battery in place
          throughout. Next, discharge the Li-ion battery again in a
          device that is going to put a heavy load on the battery,
          like an LED flashlight. Seal the Li-ion battery in an
          airtight bag and put it in the freezer for about 24
          hours, ensuring there is no moisture in the bag that
          could get the battery wet. When you take it out of the
          freezer, let it thaw for up to eight hours to restore it
          to room temperature. Place the Li-ion battery in the
          charger and charge it fully. Hopefully, its performance
          will improve, it will take a charge again and last longer
          between charge cycles.
          www . dell . com / community / Laptops - General - Read -
          Only / Best - way - to - charge - discharge - the -
          battery / td - p / 3275322"The battery can become un-useable if discharged too
          deeply. It is not necessarily shot, but the circuity
          disables the charging function, as recharging a deeply
          discharged Lithium battery can be dangerous."
 Editor's own batteries:
      Sony Energytec US18650 S STG
      (Blue colour)10 in a pack saved from a dead Compaq laptop. pairs of 2 in
      parallel, stored for years, @2021-11 4.08 V on each pair,
      except 1 pair (end of serial stack with red wire) at 2.95
      V
Panasonic Lithium Ion
      CGR18650 Matsushita Electric (Pink)15 in a pack from Black laptop.
        Dell From a Dell Latitude E6530 laptop gj@ later gave jhs@ 2021-11, battery labeled: 11.1V
        60Wh.Laptop battery light gave some unusual flickering, BIOS
        showed zero charge even after plugged in hours.
 Drilled out the plastic rivets, squeezed the case with
        movable axle pliers, to stress the glue join along the
        case, finger nail at corner, 2 screwdrivers alternately
        working along to crck the case shell apart.
 6 orange colour cells, Cells in pairs of 2 parallel wired,
        3 pairs in series.
 Cells labeled LG ABC21865 L332K276A2,
 2 thin wires: 1 green (@ 4V), 1 yellow (@ 8V), 1 red thick
        wire (@ 12V) going back from each pair of cells voltage
        stage to PCB controller of battery pack. + 2 thin black
        wires adjacent, probably a temp detector. Battery PCB
        marked Dell MaCallan
 Cell voltages (- end) 0.922 V , 1.035 V , 0.906 V (+
        end)
 Recharging: I used 50 mA into all 3 in series, within
        minutes they each went to 2.4 Volts
 
          
            
              | Elapsed Hours:Mins
 | Cell Voltage
 | Internal Resistance
 |  
              | 0:00 | 2.40 V |  |  
              | 1:30 | 3.08 V |  |  
              | 2:00 | 3.13 V |  |  
              | 2:30 | 3.25 V |  |  
              | 4:00 | 3.46 V | 1.8
              ohms |  
              | 4:45 | 3.57 V |  |  
              | 5:15 | 3.57 V |  |  
              | 5:30 | 3.57 V |  |  
              | 6:15 | 3.62 V |  |  
              | 7:00 | 3.64 V | 2.27
              ohms |  
              | 8:00 | 3.58 V | 0.56
              ohms |  
              | 8:02 | 3.57 V | 0.33
              ohms |  
              | 9:00 | 3.58 V | 0.33
              ohms |  
              | 10:30 | 3.61 V | 0.33
              ohms |  
              | 11:00 | 3.62 V | 0.39
              ohms |  
              | 13:00 | 3.67 V | 0.33
              ohms |  
              | HH:MM | v.vv V | _.__
              ohms |  
          Internal Resistance = V-on-charge = V-open-circuit / 50mA
          charge current / 3 (cells in series)
         Later when higher voltage, I will return it to standard
        charging on laptop, then as it may have lost capacity, I
        may do a discharge test, & or swap the cells for Sony cells
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