Lii-500 underreads IR if cell is overcharged?

winny

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So I got a batch of TP4056 based USB chargers (hopefully, the pinout did match but there was no print on the ICs) which unfortunatly overcharge the cells to somewhere between 4.22 to 4.30 V. Not good. Will replace the ICs.

Anywho, my four different Lii-500 chargers all reported 10 mohm IR for each overcharged cell. Seems to bottom out at 10 mohm. Highly unlikley that all cells would have that low IR.

Has anyone else observed this phenomonon?
 
winny said:
Anywho, my four different Lii-500 chargers all reported 10 mohm IR for each overcharged cell. Seems to bottom out at 10 mohm. Highly unlikley that all cells would have that low IR.

Has anyone else observed this phenomonon?
winny,
Ya gotta help me out here! What was the cell manufacturer and model#. Some high drain cells will have a very low IR (<20m?)and a Max V of 4.35V
The LGDBHG21865 comes to mind <18m? although Max V on that one is4.2 0.05V
Most cells have a V tolerance of 0.05V
Also the LiitoKala is not the most accurate with its IR measurements.
Notice the V and IR on the bottom cell of the red box. Actual IR is 52.20 and the LiitoKala shows 19

image_opmxlg.jpg


Wolf
 
The lowest resistance cell that I've found is my Sanyo NCR20700As with an average of 15mOhms DC at 4,20V.
Goes lower as the cell discharges.

A laptop 18650 will not even be close to it, so 10mOhms is obviously wrong.
 
BlueSwordM said:
The lowest resistance cell that I've found is my Sanyo NCR20700As with an average of 15mOhms DC at 4,20V.
Goes lower as the cell discharges.

A laptop 18650 will not even be close to it, so 10mOhms is obviously wrong.

Yea ditto on that.
The lowest I found in my travels was a Sony US18650VTC4at 12.85m? AC 1kHz at 4.06V and anINR18650-20R at 13.25m? AC 1kHz at 4.20V
So yea I would say the LiitoKala is not telling the truth.

Wolf
 
winnySo I got a batch of TP4056 based USB chargers (hopefully, the pinout did match but there was no print on the ICs) which unfortunatly overcharge the cells to somewhere between 4.22 to 4.30 V. Not good. Will replace the ICs.

Anywho, my four different Lii-500 chargers all reported 10 mohm IR for each overcharged cell. Seems to bottom out at 10 mohm. Highly unlikley that all cells would have that low IR.

Has anyone else observed this phenomonon?


Standard question: 4 Wire connection for IR measurement ??
 
No, all brands of cells. The built in IR measurement of the Lii-500. Discharge it below 4.2 V and it reads normal value again.

I would guess something is clipping an internal rail when the battery voltage is higher than the set CV value. Still strange caveat.
 
winny said:
No, all brands of cells. The built in IR measurement of the Lii-500. Discharge it below 4.2 V and it reads normal value again.

I would guess something is clipping an internal rail when the battery voltage is higher than the set CV value. Still strange caveat.
Sorry, but AGAIN:
is the connection to LII-500 4 wire or 2 wire ?

(Wolf, ist the LII-500 capable of 4 wire at all ?)

Update, i looked it up, it looks like a opus ? No more contacts?
(then all measurements are more or less bogus)
 
winny said:
No, all brands of cells. The built in IR measurement of the Lii-500. Discharge it below 4.2 V and it reads normal value again.

I would guess something is clipping an internal rail when the battery voltage is higher than the set CV value. Still strange caveat.

Good to know I have never experienced that.
But then again I do all my IR with a 4 wire Kelvin tester.I really dont trust these testers to give me accurate results.

Wolf
 
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