Battery
New member
- Joined
- Jan 4, 2017
- Messages
- 11
Experiment:
Resetting Current Interrupt Devices (CID's), What are the features of a heatdamaged cell?
I have just measured the internal resistance from a few cellswith initiated CID's.These cells were froman oldeight cellIBMbattery of(cream paper wrapped cells)and a 6 cell Dell battery(4.3V 28A SDISamsung cells 2013?).Out of interestI'mnot sure who made the super old looking IBM cells. They aremarked on the side withEHPPT2B and some other codesthat varies with each cell eg[012055]they haveaSstampedon the negative terminal. They use a similarfont and layout asSanyo cells.
In the IBM pack all eightcells had triggered CID's and 5/6in the Dell. Once the CID's were popped back in the IBM Cells were sittingat 1.5-3V and theSamsungat4V. Considering their salvaged voltagesI assumeboth packswould havefailed at a reasonably high sate of charge, for theSamsung 4.3V cells ~4.05V is approximately 80% SOC. Also the IBM cells seemed to vent some gas/electrolyte when I reset them.
Since almost all the CID's were triggered in the packsand thattheyindependent devices we can assume that the packs got hot also triggering thePositiveTemperature Coefficient element(PTC). The PTC can be triggered in two ways reversibly and in the case of extreme temperaturesirreversiblywhich leads to permanent damage of the cell*.
Results:
Internal resistance inmiliOhms:
IBM:2992,456,300,808,300,301,1517,250 (LOW 0% SOC)
SAM:176,200,250,220,310,172 ("working" cell)(High 80%SOC)
Internal resistance measurements are often wrong with cheap equipmentso this is but a qualitative test. For typical good cells I measure~60-150 miliOhmsTypically ~100miliOhms at 100% SOC**.What does this all mean? With fewstatistics it is hard to draw just yetthe linebut itlooks like at a high state of chargean IR of200 miliOhmsor higher could be asign of significant internal damage and reason enough to discard the cell. For a low state of charge perhaps 50-100%** more would be acceptable ~300 miliOhm for borderline OK cells.
Here is the general rule I have found posted on forums for3.6V (~0-33% SOC ***):
Milli-Ohm
Battery Voltage
Ranking
75-150mOhm 3.6VExcellent
150-250mOhm3.6VGood
250-350mOhm3.6VMarginal
350-500mOhm3.6VPoor
Above 500mOhm3.6VFail
So it seems the general wisdom is probably correct. One side note I would make issince some battery chemistriesretain a significant level of charge at 3.6V (Panasonic NCR18650B *** 33%).All things are not equal for a low SOC IR measurement until around3.4V, For now I willjust measure all IR at 100%SOC ... Unless this is a bad idea? I really should measure the IR for some cells before and after charging.
Next to do is test the capacity of these cells somewhere safe....
References:
*Safety mechanisms in lithium-ion batteries(PDF)
Journal of Power Sources 155 (2006) 401414
**IR vs SOC(PDF)
(I don't think the lithium cells here are 18650)
The table shows that when the SOC decreases from 100 to 15% the total internal resistance Ri (=Rp+Ro) increases with 50-100%,especially due to Rp. Rp has a more dynamic character in comparison with Ro which stays nearly constant. [Ri = Internal resistance (general, total)(=Rp+Ro)] [Ro =Battery internal "ohmic" resistance] [Rp =Battery internal "polarization" resistance]
***SOC vs voltage
Resetting Current Interrupt Devices (CID's), What are the features of a heatdamaged cell?
I have just measured the internal resistance from a few cellswith initiated CID's.These cells were froman oldeight cellIBMbattery of(cream paper wrapped cells)and a 6 cell Dell battery(4.3V 28A SDISamsung cells 2013?).Out of interestI'mnot sure who made the super old looking IBM cells. They aremarked on the side withEHPPT2B and some other codesthat varies with each cell eg[012055]they haveaSstampedon the negative terminal. They use a similarfont and layout asSanyo cells.
In the IBM pack all eightcells had triggered CID's and 5/6in the Dell. Once the CID's were popped back in the IBM Cells were sittingat 1.5-3V and theSamsungat4V. Considering their salvaged voltagesI assumeboth packswould havefailed at a reasonably high sate of charge, for theSamsung 4.3V cells ~4.05V is approximately 80% SOC. Also the IBM cells seemed to vent some gas/electrolyte when I reset them.
Since almost all the CID's were triggered in the packsand thattheyindependent devices we can assume that the packs got hot also triggering thePositiveTemperature Coefficient element(PTC). The PTC can be triggered in two ways reversibly and in the case of extreme temperaturesirreversiblywhich leads to permanent damage of the cell*.
Results:
Internal resistance inmiliOhms:
IBM:2992,456,300,808,300,301,1517,250 (LOW 0% SOC)
SAM:176,200,250,220,310,172 ("working" cell)(High 80%SOC)
Internal resistance measurements are often wrong with cheap equipmentso this is but a qualitative test. For typical good cells I measure~60-150 miliOhmsTypically ~100miliOhms at 100% SOC**.What does this all mean? With fewstatistics it is hard to draw just yetthe linebut itlooks like at a high state of chargean IR of200 miliOhmsor higher could be asign of significant internal damage and reason enough to discard the cell. For a low state of charge perhaps 50-100%** more would be acceptable ~300 miliOhm for borderline OK cells.
Here is the general rule I have found posted on forums for3.6V (~0-33% SOC ***):
Milli-Ohm
Battery Voltage
Ranking
75-150mOhm 3.6VExcellent
150-250mOhm3.6VGood
250-350mOhm3.6VMarginal
350-500mOhm3.6VPoor
Above 500mOhm3.6VFail
So it seems the general wisdom is probably correct. One side note I would make issince some battery chemistriesretain a significant level of charge at 3.6V (Panasonic NCR18650B *** 33%).All things are not equal for a low SOC IR measurement until around3.4V, For now I willjust measure all IR at 100%SOC ... Unless this is a bad idea? I really should measure the IR for some cells before and after charging.
Next to do is test the capacity of these cells somewhere safe....
References:
*Safety mechanisms in lithium-ion batteries(PDF)
Journal of Power Sources 155 (2006) 401414
**IR vs SOC(PDF)
(I don't think the lithium cells here are 18650)
The table shows that when the SOC decreases from 100 to 15% the total internal resistance Ri (=Rp+Ro) increases with 50-100%,especially due to Rp. Rp has a more dynamic character in comparison with Ro which stays nearly constant. [Ri = Internal resistance (general, total)(=Rp+Ro)] [Ro =Battery internal "ohmic" resistance] [Rp =Battery internal "polarization" resistance]
***SOC vs voltage