Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Lii-500 underreads IR if cell is overcharged?
#1
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?
No. cells
Indexed: 53
Processed ok, not yet indexed: ~1500
Broken down, untested: ~800
Not yet broken down: ~140 kg
Reply
#2
(03-08-2019, 03:23 PM)winny Wrote: 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 (<20mΩ) and a Max V of 4.35V
The LGDBHG21865 comes to mind <18mΩ although Max V on that one is 4.2 ± 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


Wolf
If 18 X 650 = 2200+mAh then we have power! 
May all your Cells have an IR of 75mΩ or less Smile
Last count as of 5/19/2019
Total Number of Cells                          5263
Cells  >80% of Capacity                      3703
Cells <80% of Capacity                       1535
Cells ≥2200mAh & ≥ 80% & ≤75mΩ    2563
For Info Google Drive
Not your average Wolf       
            Cool



Reply
#3
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.
The power of lithium ion is in our hands!
We'll show them what we're made of!
Reply
#4
(03-08-2019, 06:28 PM)BlueSwordM Wrote: 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 US18650VTC4 at 12.85mΩ AC 1kHz at 4.06V and an INR18650-20R at 13.25mΩ AC 1kHz at 4.20V
So yea I would say the LiitoKala is not telling the truth.

Wolf
If 18 X 650 = 2200+mAh then we have power! 
May all your Cells have an IR of 75mΩ or less Smile
Last count as of 5/19/2019
Total Number of Cells                          5263
Cells  >80% of Capacity                      3703
Cells <80% of Capacity                       1535
Cells ≥2200mAh & ≥ 80% & ≤75mΩ    2563
For Info Google Drive
Not your average Wolf       
            Cool



Reply
#5
Quote: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 ??
1 kWp in Test
4 kWh battery target - plus Mobile Home battery
Ultra low cost
Electronics ? No clue. Am machinery engineer.
Reply
#6
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.
No. cells
Indexed: 53
Processed ok, not yet indexed: ~1500
Broken down, untested: ~800
Not yet broken down: ~140 kg
Reply
#7
(03-08-2019, 08:48 PM)winny Wrote: 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)
1 kWp in Test
4 kWh battery target - plus Mobile Home battery
Ultra low cost
Electronics ? No clue. Am machinery engineer.
Reply
#8
(03-08-2019, 08:48 PM)winny Wrote: 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
If 18 X 650 = 2200+mAh then we have power! 
May all your Cells have an IR of 75mΩ or less Smile
Last count as of 5/19/2019
Total Number of Cells                          5263
Cells  >80% of Capacity                      3703
Cells <80% of Capacity                       1535
Cells ≥2200mAh & ≥ 80% & ≤75mΩ    2563
For Info Google Drive
Not your average Wolf       
            Cool



Reply


Who read this thread?
28 User(s) read this thread:
Sean, Korishan, watts-on, Stefaan De Ridder, BlueSwordM, Geek, Oz18650, djuro, Chablis_m, Crimp Daddy, Amigaman, Cherry67, 100fuegos, Sammm, Wolf, Dallski, bchur83, Gremlin, Richard, beserker786, winny, Havskum, Greenbatt, Binary, gueorgi, Irah, WimVsan, dooogs

Forum Jump:


Users browsing this thread: 1 Guest(s)