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Question about battery internal resistance meter
#1
When grouping 18650 batteries, I learned that their internal resistance is important. I decided to buy a YR1035 internal resistance meter. Has anyone used this device before? Or is there a different device to offer?
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#2
I would say its not important Persue.... Because....

Low current application and when. Testing at max current you have allready made sure the ir is low enough. As Long as you random the cells after into the packs it Will work fine..

On high current packs you Will push the cells to the limit and the its Main priority!
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#3
I have one, it shorten my testing time.
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#4
(08-03-2019, 01:59 PM)daromer Wrote: I would say its not important Persue.... Because....

Low current application and when. Testing at max current you have allready made sure the ir is low enough. As Long as you random the cells after into the packs it Will work fine..

On high current packs you Will push the cells to the limit and the its Main priority!

I will make a 21S 30 amp battery pack. My 18650 battery are Samsung, Sony, LG brand. Measured capacity values are between 2200-2500 mah. I measured capacity with lii-500 I'm going to use rePackr on the site. According to the calculation, each group is approximately 31.4 Amperes. However, the connected batteries, which are parallel in long-term use, but the batteries connected in parallel if their internal resistance is not equal in the time shorter life span due to inequality of internal resistance. Is this information I know wrong? Thank you for your help
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#5
First of all its Ah not A.. please dont mix current with capacity.


Since you test with lii i assume you Will have a max current per cell at 0.5a. thats so low that the capacity you have got that the ir is not a problem. I know this by experience.


IF you plan on higher current than that you need to retest Them ns test ir.
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#6
Maybe i am throwing oil on the fire, but i not intend to!
I have tested cells that where oke in my capacity testing but it would take them forever to charge.

Everything with a ir below 20 mohm and higher then 75 mohm is not in pw.
I had cells tested oke in the capacity test but had a IR of 150 mohm, for a cell that must have ~25 mohm?
Heaters and sd are easy to detect, with a pre ir check.

But just like daromer said: high drain powerwall test for ir, low drain not necessary.
Feel free to correct me when i am wrong

In general: what i understood:
You must know the soh%, capacity and the ir.
With the ir you can find out how hard the cell life was, if it was to hard it can be tiered?

Overall in my experience, its nice to have the ir checked, before or after the testing.
Best
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#7
I'd overlook the internal resistance to 21 S 30 Amps. I don't understand what you mean high current. example : high current : 200 Amper ? or 100 Amper? How many current
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#8
High current is running at 1A/cell or higher for standard cells (not high drain cells like power tool cells or the like). Even 500mA (0.5A) per cell of these types could be considered high current with certain types of cells.

It doesn't matter how many cells are "series", as that does not determine how many amps you can pull from a pack. "Parallel" cells is what matters for amp/current draw. If your strings are 21s1p, then 30A/cell is HUGE and should only be done with super high drain cells. If you have 10p, then that'd be 10A/cell, and again, these need to be high drain cells and laptop or similar cells will not cut it. If the packs are 30p, 1A is still high. But with 80p, that's 375mA (0.375A) would be considered a little high, but still standard and normal for these types of cells.
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#9
100kwh-hunter: If it takes forever to charge they arent in my "OK" List. That means they are screwed and self discharging during higher voltage. Those generally also have other issues like high IR.

As long as you follow a normal standard capacity test with proper current you will rule out all cells having high IR. Thats a fact since high IR wouldnt allow them to discharge or charge in proper amount of time.

With that said.. its NEVER wrong to check IR. But there is many misconceptions around how things work and why things work Tongue

High current is cells that do 5A or more in general. We could generalize around 1A but thats really not high...

With that said your applications cannot or should NOT be higher than you tested the cells if you want to follow the general guide-line that we have here on this community. So if you tested at 0.5A and you have 10 cells in parallel that would be 5A max!


With that said you mention 30 Amps all the time? If you talk about capacity its Ah not A... Capacity not Current. Please correct those in your posts so we better can understand what you are working with Smile
Korishan likes this post
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#10
Thank you for your valuable information. ok capacity not current Smile
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