Internal resistance meter

Abarth595

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May 14, 2017
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Just made my first video with the internal resistance meter as subject.
Hope you like it.

 

daromer

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Good work there m8.

You need to have very steady and tight connection between the meeter and the cell so make sure the cells are fastened to the table in some way.

Same goes with the Opus when comparing. Press the tab against the cell and you will get closer result (Im DiY tech and repairs ) :)
 

Cherry67

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May 13, 2018
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daromer said:
Good work there m8.

You need to have very steady and tight connection between the meeter and the cell so make sure the cells are fastened to the table in some way.

Same goes with the Opus when comparing. Press the tab against the cell and you will get closer result (Im DiY tech and repairs ) :)

Very good, people start to look for Impedance. Thumbs up !

Re fastening the cells, all 4 Tips must be connected for a proper measurement, then it is stable. That is a bit fumbly with this 4 stiff tips, 4 springy tips ala Wolf are probably better.
 

Wolf

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Who else is using this device to measure the IR?

ps915,

I am not using that particular one but I use the YR1030 with all of the adapters. I like it as it has silicone leads that are very flexible and easy to use.
It has 4 small contact pins with crowns on them and spring loaded. Additionally if you order from the right place it comes with a cell holder, alligator clips and probes. All 4 wire of course.

image_ludmfv.jpgimage_bluokt.jpg

I also have the allOSUN EM3610 and it is a little clumsy like the oneAbarth595 was using.TheSANPO SM8124has 2 very large contacts and rather stiff wires.
I feel that it was designed to use on larger batteries with post like terminal.

image_xojiec.jpg

I have ordered the updated version theSM8124A which looks to have the spring loaded probes that will work better with 18650s

image_pvahlf.jpg

I alsohave the BVIR 2018 coming and we will see what that brings.

image_qiohbh.jpg

I am thinking about getting theKT-2004 its a little pricey but hey you can never have too much test equipment or can you? Besides its free shipping!
Ah I ordered it why not.I like it as it allows me to choose what way I want to test my resistance as it has banana jacks so I can build my own testing rig.
Once I gather all of them together I will review them all and give a report.

image_ibixcn.jpg


Wolf


Abarth595 said:
Just made my first video with the internal resistance meter as subject.
Hope you like it.

Nice Video and good work.
Wolf
 

SurfGuruJeff

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Dec 20, 2020
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Coming from the world of drone racing, I know that Internal Resistance is the most important indicator of the health of a LiPo cell.

My chargers all have the ability to test IR and so I've been using them in harvesting 18650 cells. They are handy little chargers that are inexpensive and work well. I mount 4 cells in series into a 3D printed case, and have balance leads plus an XT60 connector to the charger. It only takes a few seconds to check 4 cells (I can do up to 6 cells at a time if I 3D print a larger case) I get good enough readings using this method to sort out the good from the bad. I'm just beginning my journey with 18650 batteries, so my process will speed up as I grow.

I'd encourage people to heavily rely on IR as the benchmark for cell health! If I throw on a 6S LiPo pack and the performance while drone racing sucks, then I know there's one cell or more that has high IR, and sure enough the charger/tester reveals 5 good cells and 1 with higher IR. These are dangerous in the LiPo world and will first heat up during charging, then as the IR gets worse and worse, there's risk of fire. Higher IR batteries also don't hold 4.2v for long.

I recently got 2 packs of E-bike batteries and one pack had good enough IR in the 45mOhm range, but the other pack had cells which were in the 75-90mOhm range, which I anticipated wouldn't even hold a charge above 4.10v for long, which I was right about. I'd say the equipment doesn't have to be uber fancy or expensive, just as long as it is giving fairly consistent readings.

Oh, and I haven't seen much talk about temperature... temperature has a big effect on IR. When it's cold, you can expect a much higher IR reading vs when the cell is warm. Try testing a cell at 40F and again at 80F and you'll be shocked (pun?).

By the way, this is my first post on the forum, so hello world!
 

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daromer

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Though note you cant compare drone racing batteries with cells for a powerwall (I have raced alot too and started even before KK was defacto ;) )
In drone racing we talk about 50-100C or even higher draw. On a powerwall we talk about 0.1-0.5C at most. Quite a difference in terms of IR :)

And yes temperature is a factor. If you start digging through you will see many of the threads taking up both temperature and IR. Wheres Ir is mainly used for weeding out bad cells as a start and i would say "never" used when building a powerwall pack. Note that many powerwalls have 100s of cells in parallel :)

But to end with it. They are key factors but you need to put them into relation to each other as well :)

In High current apps ir is key. In powerwall i would say cell self-discharging and or SOH is the key component.

And Welcome SurfGuruJeff. I bet you will learn alot and even worse. You will see how different the applications are :D
 

SurfGuruJeff

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Though note you cant compare drone racing batteries with cells for a powerwall (I have raced alot too and started even before KK was defacto ;) )
In drone racing we talk about 50-100C or even higher draw. On a powerwall we talk about 0.1-0.5C at most. Quite a difference in terms of IR :)

And yes temperature is a factor. If you start digging through you will see many of the threads taking up both temperature and IR. Wheres Ir is mainly used for weeding out bad cells as a start and i would say "never" used when building a powerwall pack. Note that many powerwalls have 100s of cells in parallel :)

But to end with it. They are key factors but you need to put them into relation to each other as well :)

In High current apps ir is key. In powerwall i would say cell self-discharging and or SOH is the key component.

And Welcome SurfGuruJeff. I bet you will learn alot and even worse. You will see how different the applications are :D
Yeah, totally! I was speaking in general, because I know not everybody is using their cells for Powerwall applications (mine will be for my E-bike), but I have taken advantage of fact that overall IR goes does with the number of cells in parallel... I hacked up a bunch of old LiPo cells to make one big battery. On their own they couldn't perform for a drone, but in parallel they can pump out a lot of amps for my portable charger. But it is definitely Frankenstein! It's 4S18P and makes for a handy little power bank.

What is the point at which you wouldn't even trust it in a Powerwall? I was thinking any IR over 120mOhm would be too high, but I'm not sure.
 

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daromer

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I dont personally have a ir guide line as such. Im more of if it can sustain my tested current its ok for powerwall. Ie i test at 1A and if it pass without issues of heat and all that they work fine in my powerwall where they never sees that high current. You could say i have tested the IR.

Other here do the other way around by testing IR first and weed out the cells. You can do it in both ways i guess. Generally i wouldnt allow 18650 above 80mOhm into any pack. Im talking about AC ir now and note that DC vs AC is different.
 
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