building pack unsure what is high internal resistance 18650 cells

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jon218white

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Jul 18, 2019
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125
hello
im building a 12s9p 18650 pack for a skateboard i have teted all my cells but unsure what is high internal resistance ?
have lots of 18650s and want to reduce the likleyhood of building a bad battery using high internal resistance cells, my highest so far is 80 ohms
thankwe
 

OffGridInTheCity

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Dec 15, 2018
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Jonisingt35r said:
hello
im building a 12s9p 18650 pack for a skateboard i have teted all my cells but unsure what is high internal resistance ?
have lots of 18650s and want to reduce the likleyhood of building a bad battery using high internal resistance cells, my highest so far is 80 ohms
thankwe
@Wolf has done extensive data gathering on battery types and their IR and what's good. See this thread, 3rd post, "Harvest.xlsm"for a spreadsheet download with much info. https://secondlifestorage.com/showthread.php?tid=9006&highlight=wolf

A
nd search "wolf" for other discussions and info and downloadson IR.
 

jonyjoe505

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Feb 28, 2018
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I been playing around with my yr1030 IR tester, I tested hundreds of cells, I would say anything under 65 milliohms is ok for a pack, that is my cutoff for me. But I don't use in a high drain device. Batteries at 80 milliohm or higher got hot during testing and were taking longer to reach 4.20 volts and had lower capacity.

But for a high drain application I would go even lower. Some of the high drain sony's (powertool batteries) are less then 30 milliohms, I seen the panasonic at about 34 milliohms, the red sanyo's in the 45 milliohms for the ones with 2500 capacity. I seen some blue samsung cells less then 20 milliohms. In your situation i would stay under 50 milliohms.

But with laptop batteries its rare to get under 40 milliohms, I was lucky to get the panasonic in just one pack total 9 cells, those are definitely premier batteries all testing at minimum 2900 mah.


image_fkdqtk.jpg
 

jon218white

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thanks
 

mikenr

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Apr 21, 2020
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Hi there,

I just got my yr1030 yesterday and started testing the 500 18650s that I bought, they are Moli ICR-18650H cells - none have an internal resistance of less than 73 milliohms, and the average would be just over 80... A few are over 100.

They were sold to me as tested cells, the capacity has been written on each cell and the marks from spot welding ground off both ends. The seller has great ratings and they were sold as second hand but unused.

Does anyone have any idea what is a typical IR for these cells? I have checked Wolf's database and unfortunately no info there.

Any help very much appreciated, along with any advice as to what I should do with the 100+ milliohm cells.

:)

Many thanks!
 

Wolf

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Sep 25, 2018
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mikenr said:
Hi there,

I just got my yr1030 yesterday ..............t, they are Moli ICR-18650H cells - none have an internal resistance of less than 73 milliohms, and the average would be just over 80... A few are over 100.
............ I have checked Wolf's database and unfortunately no info there.................
mikenr,

First off congratulations on a giant leap into proper battery testing with the purchase of the YR1030.
I do have some information on the Moli ICR cells. They areLithiumcobalt oxide cells generally low drain high capacity.
The ICR-18650H is a 2100mAh cell. I probably haven't come across anyso that may be why they arent in my analysis sheet.
But have no fear I have plenty of ICR-18650Jand ICR-18650K cells to go by.
I find that most manufactures like Moli do not change their cell chemistry for mAh results they just add more product to each cell.
In essence it is just a heavier battery.
I have been fortunate enough to test 101 of these gems. :p

Results with lowest IR.

image_onkwyw.jpg


Results with highest IR.

image_ojcscg.jpg


My database info on them.

image_jdhzwq.jpg


My best guess at proper IR values.

image_agmqln.jpg


That's what I have.

As far as a cell (actually any cell)with > than 100m? I'm not to fond of. What do they test out at?
Best guess with the data that I have is that anything >80m? is marginal at best with ?80% SOH.
Any cell <80m? down to my lowest at 56.1m? seem to perform OK with obviously the lower the m? the better the chances.


Wolf
 

daromer

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The IR is HIGHLY dependant on the application. On RC cells you dont want IR above 5mOhm... Meanwhile a laptop is generally below 60mOhm and for many of us we can go up to 100 or so without noticing it.

The internal resistance affects voltage drop and we all know voltage drop = heat = wasted energy.
 

Wolf

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daromer said:
........... Meanwhile a laptop is generally below 60mOhm and for many of us we can go up to 100 or so without noticing it.

The internal resistance affects voltage drop and we all know voltage drop = heat = wasted energy.

Correct daromer.

It took my quite a while to find 4 cells with close mAh results and very different IR readings.
I just did this experiment a couple of days ago.

4 cells

1 INR18650PHH 1782mAh 39.89m?
2 LGDAS31865 2004mAh 71.02m?
3 UR18650E 1871mAh 36.29m?
4 UR18650FJ 1853mAh 62.55m?

I couldn't find any >80m? cells as they are all gone to the recycler. OOPS.
We may not notice the 100m? cells but the other cell certainly do :p

All in all if you stay in the 4V to 3.5V range there is not much going on between the cells but when you get outside of those parameters then things start to happen.


image_yhyskr.jpg


Also the charging profile is very different between these cells.


image_pcocfx.jpg


Wolf
 

daromer

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5,671
What many doesnt see is that they are uneven now in beginning. The cells that is capable with higher current have lower ir and will be stressed more. But that is not really a bad thing since they are often in better condition than the ones with slightly higher IR.

I did post a rather large paper on FB the other week. Like 250 pages testing this and its quite interesting. In their tests the cells did level out a bit after some decent amount of cycling :)

Something for you to test Wolf :D
 

mikenr

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Apr 21, 2020
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Many thanks for the very useful info Wolf.

I noticed in the tests that you shared none of them were done with a yr1030 does it make any difference if one is testing with another instrument?

Unfortunately I would say the average IR of my cells is just over 80 millohms :-/ Few are in the sixties and the majority low to mid eighties.... The average voltage of each cell would be 4.15v I would say, some are even at 4.2v !
 

Wolf

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mikenr said:
Many thanks for the very useful info Wolf.

I noticed in the tests that you shared none of them were done with a yr1030 does it make any difference if one is testing with another instrument?

mikenr,
The use of the YR1030 is slightly obscured on the sheet with the sorting pulldown.
Sorry for the confusion butALL my cells where checked with the YR1030 family of testers.

image_lnmute.jpg

So yes allmy IR tests are done with either a YR1030, YR1030+ YR1035+ or as of late a RC3563 all of which are
within?Vand?? tolerancesof each other so no deviation there. Short of spending $5000.00 on a Keithley you have a very accurate m? tester with the YR1030 family of testers.
Yes I have all these testers and have checked them with my reference block for V accuracy and R accuracy.

image_ujtait.jpg

image_sftssf.jpg

image_sybbgm.jpg

image_opeqzi.jpg

image_bnneia.jpg


Here is my V refboard and 10m? reference

image_mnfema.jpg

And I have 3 Fluke DMMs To collaborate with each other. If all 3 read the same its got to be right. :p

image_wpzwas.jpg




Wolf
 

mikenr

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Oh my god!!! haha I was just wondering and now I know :) Many thanks again!
 

Wolf

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daromer said:
I did post a rather large paper on FB the other week. Like 250 pages testing this and its quite interesting. In their tests the cells did level out a bit after some decent amount of cycling :)

Something for you to test Wolf :D

daromer,
Could you give me the link to that post please?
Ha more testing OK I'llbite.
Wolf
 

mikenr

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Wolf, I know this will be blatantly obvious to you and please excuse my ignorance....

So the majority of my cells tested with an IR of around 80-85 milliohms with the yr1030, the seller had written the capacity and IR on the side of each cell having tested them with a Liito Kala Lii-500

Sometimes the results were similar and more often than not way way different, either higher or lower. I know you know why this happens :) can you explain for me?

I contacted the seller about the high IR on the majority of the cells, he asked if I had discharged the cells to 3.6volts before doing the resistance testing (which I had not) most were 4.15 or more, does the voltage of the cell make much difference when testing? Again please excuse my ignorance, I'm on a steep learning curve here :)
 

Wolf

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mikenr said:
I'm on a steep learning curve here :)

Ha Ha dont spin out or fall of it will only get better...............
mikenr,

I can go with what I have for results on the Moli-Energy cells that I have tested and say that voltage has very little effect on the IR of these cells.
Most of them measure a little less or a little more in m? after a full charge.
If the seller tested the IR with the Liito Ks then that IR is way off. The Liito Ks dont test the cells with a 1KHz 4 wire test they run a simple V drop test and calculate the DC IR which in its own right is OK but not the accurate way. Additionally the charger contacts themselves add a considerable amount of m?s to the mix.

Here is a chart of all the Moli-Energy cells That I have tested with the Liito Kala Lii-500 These are the slightly higher capacity cells2300mAh and 2600mAh ones.

image_aycylf.jpg

The fact remains the same, the IR doesn't change that much from before the test and charge, to after the 30+ days recheck. That goes for all cells I have checked from all manufactures except the SONY GR series.(That's a strange cell) :huh:
The Manufacture of the Moly-Energy cells claims that an IR of ?80m? is acceptable for their J and K series I was not able to find the spec. for the H series but I would imagene it is about the same.
I did finda Moli B that is close to the MoliH at 2250mAh that says 75m? max.

image_mjizrj.jpg

Do your own experiment with them. Discharge 4 cells with your Liito K and measure the IR and then charge them and repeat the IR check.
Slap the data into a spreadsheet and slowly you will find a correlation.

Also since this is a 2200mAh cell what are you getting for results?

Link to molicel product infohttp://www.molicel.com/products-applications/explore-by-product/

Wolf
 

mikenr

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Amazing! Many thanks Wolf, I knew you would know :)

When I started out on this project I only had in mind to buy cells and build a battery for my house. Thinking I would buy cells tested and sorted by someone else, so I don't own a Liito K.... :-/ After reading around the forum I realised that testing the cells with a yr1030 makes a lot of sense, so I bought one - now I realise that in the future I will start harvesting cells so my next purchase is a Liito K (by the way, is there any particular one you would recommend?)

Do you think there's much possibility that my yr1030 is calibrated badly? is there any simple way of checking it? (I imagine 'no' is that answer to that)

Many many thanks for all your help and for sharing your immense knowledge! :)
 

Lithiumseller

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Mikenr:put cells with similar resistance into parallel, it will give less heat when charging or discharging powerwall.
 

Wolf

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mikenr said:
............. now I realise that in the future I will start harvesting cells so my next purchase is a Liito K (by the way, is there any particular one you would recommend?)

Do you think there's much possibility that my yr1030 is calibrated badly? is there any simple way of checking it? (I imagine 'no' is that answer to that)


mikenr,

The Lito K would not be my first choice.
If you can afford it and have some time to learn the SKYRC MC3000 menu and its capabilities I would get that one. But at ~$130.00 it is expensive but well worth it. It can graph the process on your PC and also on your phone.


My second choice would be the OPUS because it does 1A/1A/1A CDC(Charge/Discharge/Charge) and relatively simple to use. I also believe that is what you should go with. (If you don't have the means to go with the SKYRC)It is a standard that is liked here and I have grown to accept it even if it is around 3% to 5% high in its results.

One thing you want to remember if you are going to purchase a charger/tester stick with one make and model not like me and have them all. LOL

It will make it easier for you in the long run and not have to second guess the results.



My third choice is the Foxnovo S4 only because it is simple and easy doesn't have a lot of bang and whistle,the only downside is it does a CDC at 1A/.5A/1A but it seems to be relatively accurate.



Test results of these charger/testers with the same battery inall 4 slots.


image_jkexpd.jpg




I highly doubt your YR 1030 is miscalibrated and as you know I have several of them and they all read the same values. (at least so close that it is negligible)The best way to test the YR1030 is get a reference resistor https://www.rhopointcomponents.com/isabellenhuette-pbv-series(I have 1 for 10m?) or some nickel strips with a known m? value for a certain distance. Even a 1? resistor from anybody will give you an idea if your YR1030 is off. But I highly doubt it. I believe your cells are just high IR.



Wolf
 

mikenr

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As always Wolf I appreciate your advice very much indeed. I'm crazy busy at the moment, but when I have time I will check out the SKYRC MC3000 and if I think it's too much for me go for the Opus ;)

Have a great weekend!


Lithiumseller said:
Mikenr:put cells with similar resistance into parallel, it will give less heat when charging or discharging powerwall.

I wish I had known that 4 days ago when I was building the now built battery pack... But thank you for the advice :)

BTW from where do you source your cells?
 

Lithiumseller

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mikenr said:
As always Wolf I appreciate your advice very much indeed. I'm crazy busy at the moment, but when I have time I will check out the SKYRC MC3000 and if I think it's too much for me go for the Opus ;)

Have a great weekend!


Lithiumseller said:
Mikenr:put cells with similar resistance into parallel, it will give less heat when charging or discharging powerwall.

I wish I had known that 4 days ago when I was building the now built battery pack... But thank you for the advice :)

BTW from where do you source your cells?

https://ma.linkedin.com/in/aneta-jaskula-228b6933/de

 
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