Red Sanyo 18650 Cells Getting Hot While Charging

Wolf

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resr

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By the spreadsheet most of my cells are bad, but very few amongst new found were heaters (Samsung ICR18650-22FU at 66mOhm were, but LGCP218650 at 105mOhm were not heating up with stable charge holding).
 

Wolf

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resr said:
By the spreadsheet most of my cells are bad, but very few amongst new found were heaters (Samsung ICR18650-22FU at 66mOhm were, but LGCP218650 at 105mOhm were not heating up with stable charge holding).
The cells you checked and compared to the spreadsheet are not necessarily bad just not optimum performance. The spreadsheet was designed with >80% SOH in mind. It also has really nothing to do with heaters.
The heater argument goes like this:
Most heaters have high IR not all high IR cells are heaters.

The chemistry between different cell manufactures /cell part number andalso the cell application design in mind have a lot to do how cells react to different charging and discharging scenarios. It is best to read the manufacturers spec sheets if available.

So tell me the Samsung-22FU at 66m? what was the heat cut off? 45 C, 50C or more? If you did manage to get a mAh reading I'm sure it was in the 1500mAh to 1800mAh at the highest,68% to 81% SOH respectively

On your LGCP218650 I only have 5 tested in my database all with a SOH of 65% with an IR of ?63m?
1600mAh for a 2500 mAh cell is not a good result.
Can you share with us what your mAhresults where for theLGCP218650 with an IR of 105m?.

Case and point on IR:
Take a LGDAS318650 cell. This cell seems to thrive on high IRup to 80m? and it is still a solid performer.
Matter of fact I have had several with over 100m? test at ?100% SOH. Would I use it in my powerwall? Not a chance.
Flashlight you betcha.

Wolf
 

resr

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Unfortunately the "charger" (usb power bank with a lid) I just happened to have (when I found a pile of batteries) has only four dot charge level display. I'm planning to get a better charger next month.
 

Wolf

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resr said:
Unfortunately the "charger" (usb power bank with a lid) I just happened to have (when I found a pile of batteries) has only four dot charge level display. I'm planning to get a better charger next month.
Ah OK
Once you get a Charger/Analyzer you will see how my spreadsheet will make sense.
What model are you thinking of getting.?
Wolf
 

giacomo160

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resr said:
It may be PTC protection element built to the positive terminal that deteriorated with use andheats up the battery. I have CGR18650CE that did the same thing._

If it is so we could try to do others experiments:

a) Test the internal resistance when the cell is very hot and test them again after it is cooled down and saw if there is an added contribution to the resistance from the ptc

b) Cool down the cell while it is charging (maybe with one of those ice gel pack normaly used for traumas), the ptc resistance should drop down and the cell should complete the charge
 

resr

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If it is so we could try to do others experiments:

a) Test the internal resistance when the cell is very hot and test them again after it is cooled down and saw if there is an added contribution to the resistance from the ptc

b) Cool down the cell while it is charging (maybe with one of those ice gel pack normaly used for traumas), the ptc resistance should drop down and the cell should complete the charge
Luckily I just had a pair of purple ring Sanyo's go heater on me so I tested that idea. Looks like my theory was wrong, the resistance rised up few milliohms after cooling. Most likely it is chemistry that is a cause of heating._
 

Wolf

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Luckily I just had a pair of purple ring Sanyo's go heater on me so I tested that idea.
OK great! You had some Sanyo UR18650A 2200mAh cells exhibit heater symptoms. I'm just curious what was the initial mΩ and voltage of the cell before it was tested and "became a heater"? Not sure what you mean by " Most likely it is chemistry that is a cause of heating" as I have tested, charged and discharged hundreds (301 to be exact) let alone IR and voltage tested over 500 of the UR18650A purple/white insulator Sanyos. With proper IR I have had not 1 heaters. I'm sure the chemistry didn't change between your purple ring models and mine. This is not to be critical of your post. I am glad someone is investigating the phenomenon a little deeper than I. I just bin any UR18650A over 60mΩ and have no heater issues. Also if you could for my learning experience publish the mΩ of the battery "hot and cold" sometimes 1-2mΩ can make or break a battery. Actual numbers are important as we all try to understand theses elusive issues with heaters.

Thanks

Wolf
 
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Bubba

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I am wondering, in my experience the heaters all seem to start heating at 4.1V where they seem to get stuck. (I started also using the RC3563 and 4-wire IR to eliminate heaters)
Could they still be used in a pack that cycles between say 3v and 4v without issue?
 

Wolf

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I would not use them in a pack even if it is set to statically keep them between 3v to 4v. They are higher than normal IR to begin with and that doesn't bode well if you mix them with good cells with lower IR causing the "good" cells to experience more stress as they take up the brunt of the burden especially as the voltage rounds the corner under 3.5v. I'm sure you have seen my study on how IR influences the discharge curves between cells that have different IR. Even at low discharge current 250mA that behavior is evident.

Wolf
 
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