Question about battery internal resistance meter

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?

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 have one, it shorten my testing time.

daromer said:

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!

Click to expand...

Iwill 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 capacitywith lii-500 I'm going to use rePackr on the site. According to the calculation, each groupis 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 timeshorter life span due to inequality of internal resistance.Is this information I know wrong?Thank you for your help

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.

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%, capacityand 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

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

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.

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

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

Thank you for your valuable information. ok capacity not current

nero1986,

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?

I have used and am using the "device" I have 4 variations of this meter. I would not use anything else unless you want to spend $4000 on aKeithley DMM7510!

Click to expand...

As you all know I live and die by IR.

So to read all these post on the discussion of IR for high drain, low drain, IR matters , IR doesn't matter I have to chuckle to myself as yea some of you have experience with IR and some don't.

Now does anybody have (I haveas of last count) 6087 cells that they have tested AND recorded the IR and V before the capacity test and then recorded the IR and V after the capacity test after a minimum of a 30 day rest.

If you do great please share this data. My guess nobody has so all this discussion is hearsay, personal opinion and possibly some experience.
There is one small clue that IR is somewhat an important factor as most but not allmanufacturer include it in their spec sheet.
Now why would a manufacturer include a non important measurement like IR in their product spec sheet?
I don't know? Why would a car manufacturer include tire pressure or oil type and weight in their spec after all who cares if we have the wrong tire pressure or oil in our car worst that can happen even if we drive it slow is blow a tire or maybe even a motor. After all who cares what the tire pressure is. Well I can tell you that I do especially after I put 4 Michelins on, dam they cost a lot.

All I know is that before I consider IR as an important factor in my harvesting strategy my harvest sheet looked like this.



And after taking IR into consideration my harvesting sheet look like this.




The difference is It takes me 5seconds at the most 10to test the IR and V of a cell and see if it is a good candidate .
Sure I could just throw all of the cells that I harvest into the chargers to tell me if they are good or not.To some that way of doing it is fine so be it. Let them continue to do it the way it has been done from the beginning.

I am not here to change anybody's mind just to demonstrate with research and FACTS that IR is a very important measurement to take.
In the beginning I was happy to have cells over 2000mAh come out of my testers just to discover that the cell is a 3000mAh cell and has only 70% of its capacity and eventually found out that the IR was too high for that brand of cell and I should really never have wasted my time on it.

So for those that don't care about IR and an enlightened way to harvest cells no problem stay where you are I am sure you will do just as well with or without IR. Its like the elderly man who never knew what the internet is or how to use it. If you never know about it you would not miss it. But take my IR meter away from me man there will be bloodshed.

Wolf

@ Daromer,
Cells at 2-3ah that i charge with 1 amp for over 4 hours, then they are not oke and will not be in my pw.
I must admit i could have spend some more time on writing.

Cells with a odd ir, i don't even test further, thanks to the Wolfman.

@ Wolf, i would be happy to give you a copy of my data, if it is something for you.
I am not a xls pro, more a dummy, so every cell type/mfg has his own sheet.
And a max of 100 cells in a sheet to get only the proper ir for that specific cell.
You will also find data from cells that i don't even want to have, so that sheet has data for ~10 cells.

Best