This is why i don't trust liitokalas...

106E

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Nov 27, 2020
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This is why i don't trust liitokala lii-500 to check internal resistance, every time i plug i get a new result, and comparing this to a Yaorea you can see a big difference hehe :)
 

floydR

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Aug 23, 2017
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996
Should be in Battery chargers and testing forum
later floyd
 

Wolf

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Sep 25, 2018
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Yep no news here. But thanks for pointing it out. Always good to see the proof video taped.
But nuckle protecting gloves are sligtly dramatic I think. 🤣
Nevertheless there are apples and oranges being compared here.
One of these (Apples) is the LiitoKala Lii-500 or (X) where X = any commercial battery tester/analyzer/charger. I.e. Opus , Zanflare, yes even SKYRC 3000 and the new Megacell charger etc. These units measure "IR by a simple voltage drop method.
Not that there's anything wrong with that other than the complete inaccuracy of measuring such as miniscule resistance without the benefit of a kelvin 4 wire system.
Sticking with DC IR (Apples) and the commercial testers, there is no "standard" for a DC IR test.
At what voltage or SOC do you test for DC IR? 3v, 3.6v, or 4.2v?
What load do you put on the battery 0.5Ω, 1Ω, or 4Ω?
How long do you apply the load 5ms, 100ms, 500ms or maybe 1s and at what point of time in the load application do you measure your Voltage drop and amperage to calculate the IR? Or you calculate the Amperage by a known resistor value that has more than likely a ±5% tolerance
This all done without the benefit of a 4 wire test as far as I am concerned is a sales gimmick.
You get the idea.
The (Oranges) YR1035 series IR meters are 1kH AC IR 4 wire impedance testers. As is my favorite the RC3563. These meters measure the AC IR using a 1Kh AC sine wave to measure the impedance of the battery giving you a true internal resistance of the cell. It is independent of SOC and battery voltage hence allowing you to determine the health of the cell even at total DOD ≈2.5V and even lower.

Here is an example of the results of my DC IR testing rig I built using a 4 wire battery holder and an ESP32.
1614690253269.png1614690337349.png
Given the battery is in a good SOH and SOC the IR readings will be relatively consistent and repeatable. But this is also a 4 wire tester.
This particular cell had an AC IR of 52.22mΩ and a DC IR average of using different resistors and load initiation methods (Relay/MOSFET) of 82.065mΩ which is usually the average outcome of DC IR being x.5 to x2 the AC IR of a good cell.

Why your LiitoKala showed such a low IR I have no idea. But in the final analysis you are absolutely right not to trust the IR readings of the LiitoKala. The same goes for all other reasonably priced commercially available battery analyzer/charger/testers.
Good work @106E!!(y)

Wolf
 
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DiggsUt

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Oct 30, 2019
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65
Actually I was impressed the LiitoKala was that accurate. After all, I don't care if a battery is 22 or 30. I just need to know if it is in the 20-30s range or 120s-130s.
 

Wolf

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Sep 25, 2018
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Actually I was impressed the LiitoKala was that accurate. After all, I don't care if a battery is 22 or 30. I just need to know if it is in the 20-30s range or 120s-130s.
I must kinda snicker and mean no disrespect to you as far as the accuracy of the LiitoKala is concerned. I have in my database a comparison of 1439 cells between a YR1035 and the LiitoKala and the results would not be called "accurate". Just because the LiitoKala says its XXmΩ does not mean its not higher or lower.
Here is a snippet of the database filtered for just LiitoKala.

1614793648517.png
The whole database of 6225 cells can be viewed or downloaded here. https://drive.google.com/file/d/1NujY1eO6MKwGrpyEm185m6vpkMdb_Gp9/view?usp=sharing

Wolf
 
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