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18650 sanyo cells get's very hot
#1
hello dear friends.

i have a lot of 18650 sanyo red cells. they are all from old laptop batteries.
when i put them in a smart charger, while discharging they get extremely hot so i cannot even touch them.

is that dangereous? i should get rid of them?
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#2
Yes. It's a common problem with Sanyo cells. Do not use those hot cells in any kind of build/project. They should be discarded/recycled.
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#3
If you want more details, you could search the forum for "Sanyo Heaters", and you'll get a lot of threads one the topic. Some even go into deep detail as to "why" they get hot, and possible options to do with them
Proceed with caution. Knowledge is Power! Literally! Cool 
Knowledge is Power; Absolute Knowledge is Absolutely Shocking!
Certified 18650 Cell Reclamation Technician

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#4
Some Sanyo cells are heaters, and some are not.

Junk the hot ones, keep the rest.
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#5
Let me guess.

Did you get the Sanyo 18650s from battery packs between 2012-2016?

If so, then I would either be careful when testing for some characteristics, or just throw them out.
The power of lithium ion is in our hands!
We'll show them what we're made of!
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#6
I never encountered them to overheat while discharging.

The ones overheating at charging I eventually recovered by giving them 3 day breaks and then continuing charge.

What current do you use for discharging ?
It could be too much for them.
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#7
It is so funny to see this topic (18650 sanyo cells get's very hot) come up time after time.
Also the same answers time after time. Well some Sanyos are just "Heaters". Maybe we need a FAQ for that subject alone.

The reason Sanyos have become known as heaters is that everyone just seems to throw these cells with a reasonable Voltage usually >2.8V into a charger at 1A and wonders why some get hot and some don't. Gee I had 2 cells both at 3V and one got blistering hot while the other one stayed nice and cool what's up with that???? is always asked. There really is a simple solution to this puzzle and yes you guessed it it is IR!!!!
( I probably should change my user title from Senior Member to a custom one "IR King") Big Grin

So I will give everyone a challenge that is interested:
If you purchase a 4 wire kelvin 1kH AC mΩ meter such as this. YR1030 

and use it properly to measure the IR of Sanyo cells with an initial Voltage of at least 2.5V and according to this IR guideline.

Then if you get more than 5 heaters (>35°C  with a 25°C ambient temperature charging at 1A) in 100 (one hundred) cells (or more than 1 in 20) I will pay for the IR tester up to $60.00 US
That is how confident I am that this "Heater" issue can be put to rest once and for all with a simple ~50 dollar tool and a precharging IR check. Besides once you have the IR tester you will wonder how you ever survived without it. 
Please be sure to record all your findings in a proper format to receive the prize money.
Any questions just ask.
These cells in the picture were all within my IR limiting criteria and not a 1 was a heater. This is just a sample. My data for the IR criteria comes from 1348 Sanyo cells tested and recorded.


I am putting my money were my mouth is so anyone up for the challenge?

Wolf
rodagaster and jonyjoe505 like this post
If 18 X 650 = 2200+mAh then we have power! 
May all your Cells have an IR of 75mΩ or less Smile
Last count as of 6/10/2019
Total Number of Cells                          5940
Cells  >80% of Capacity                      4334
Cells <80% of Capacity                       1605
Cells ≥2200mAh & ≥ 80% & ≤75mΩ    2800 +236
For Info Google Drive
Not your average Wolf       
            Cool



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#8
(05-02-2019, 03:23 PM)Wolf Wrote: It is so funny to see this topic (18650 sanyo cells get's very hot) come up time after time.
Also the same answers time after time. Well some Sanyos are just "Heaters". Maybe we need a FAQ for that subject alone.

The reason Sanyos have become known as heaters is that everyone just seems to throw these cells with a reasonable Voltage usually >2.8V into a charger at 1A and wonders why some get hot and some don't. Gee I had 2 cells both at 3V and one got blistering hot while the other one stayed nice and cool what's up with that???? is always asked. There really is a simple solution to this puzzle and yes you guessed it it is IR!!!!
( I probably should change my user title from Senior Member to a custom one "IR King") Big Grin

So I will give everyone a challenge that is interested:
If you purchase a 4 wire kelvin 1kH AC mΩ meter such as this. YR1030 

and use it properly to measure the IR of Sanyo cells with an initial Voltage of at least 2.5V and according to this IR guideline.

Then if you get more than 5 heaters (>35°C  with a 25°C ambient temperature charging at 1A) in 100 (one hundred) cells (or more than 1 in 20) I will pay for the IR tester up to $60.00 US
That is how confident I am that this "Heater" issue can be put to rest once and for all with a simple ~50 dollar tool and a precharging IR check. Besides once you have the IR tester you will wonder how you ever survived without it. 
Please be sure to record all your findings in a proper format to receive the prize money.
Any questions just ask.
These cells in the picture were all within my IR limiting criteria and not a 1 was a heater. This is just a sample. My data for the IR criteria comes from 1348 Sanyo cells tested and recorded.


I am putting my money were my mouth is so anyone up for the challenge?

Wolf

I use the same IR tester, but IR was never a good predictor for heaters in my database. 
I have a lot of Sanyo cells with very low IR (even low in the same bunch) and there was no correlation between heaters and ir.
Only for self discharging the IR seems to be a low quality predictor. In combination with the relative capacity the self discharging rate is predictable. But also with very big deviation and only the self discharging rate in 14-30d. 
If i would have more data i would be able to programm a statistcal predictor for self discharging by given relative capacity and pre IR.
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#9
(05-02-2019, 03:23 PM)Wolf Wrote: ( I probably should change my user title from Senior Member to a custom one "IR King") Big Grin

And what am i ?? Big Grin
1 kWp in Test
4 kWh battery target - plus Mobile Home battery
Ultra low cost
Electronics ? No clue. Am machinery engineer.
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#10
(05-02-2019, 05:59 PM)Cherry67 Wrote:
(05-02-2019, 03:23 PM)Wolf Wrote: ( I probably should change my user title from Senior Member to a custom one "IR King") Big Grin

And what am i ?? Big Grin

Oh you are the IR god Big Grin

Wolf

(05-02-2019, 05:51 PM)drbacke Wrote: I use the same IR tester, but IR was never a good predictor for heaters in my database. 
I have a lot of Sanyo cells with very low IR (even low in the same bunch) and there was no correlation between heaters and ir.
Only for self discharging the IR seems to be a low quality predictor. In combination with the relative capacity the self discharging rate is predictable. But also with very big deviation and only the self discharging rate in 14-30d. 
If i would have more data i would be able to programm a statistcal predictor for self discharging by given relative capacity and pre IR.

@drbacke

It may not necessarily be the best predictor of heaters but it is a pretty good start. As you can see by my stipulations to the challenge I did leave myself a 5 cell per 100 leeway. Which is a 95% success rate any way you look at it. Plus the added bonus of my IR cutoff chart is that these cells will produce at least 80% capacity. Now there is such a thing on the Sanyos as a too low of an IR and maybe I should have mentioned that. The chemistry in question really is usually ICR low drain and anything <30mΩ on that type of battery is to be questioned. I have had some UR18650FM cells with an IR of 23mΩ to 26mΩ. Those normally run in the >45mΩ  range, that were almost instant heaters. 

As far as the SD's are concerned IR is absolutely a great indicator the cell will degrade in the 14 to 30 days to an unacceptable V level.
But in the final analysis IR is really important in the determination if a cell is healthy or not. Unfortunately with the many different chemistries out there (slight difference as they may be) between different manufactures and different part numbers the IR measurement fluctuate widely
between cells. But one thing I can tell you for sure any 18650 cell with a reading of 100mΩ or more is not worth messing with. 

You are always welcome to check my data out as it is on my google drive.

Wolf
If 18 X 650 = 2200+mAh then we have power! 
May all your Cells have an IR of 75mΩ or less Smile
Last count as of 6/10/2019
Total Number of Cells                          5940
Cells  >80% of Capacity                      4334
Cells <80% of Capacity                       1605
Cells ≥2200mAh & ≥ 80% & ≤75mΩ    2800 +236
For Info Google Drive
Not your average Wolf       
            Cool



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