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#1
I have six cells of the LG (LGDAS31865) but the problem is that take a long time to charge. I'm charging with TP4056 module at 1 Amper and when it reaches 3.9v this stop of charge, I left about 4 hours charging and when I went to measure it was in 4.16v on board, but when I remove the cell it was in 3.99v, it's normal ? Because the others cells didn't take so long
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#2
The cell can no longer hold the capacity well. It's probably left with very little capacity.
You should measure capacity.
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#3
Self discharging cells ?
Sounds like you should recylce the cells.
later floyd
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#4
Yep typical of a discharging cell.

See graph below from a tp4056 charger trying to charge a cell that wont hold capacity

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#5
(07-17-2020, 11:39 AM)fisht99 Wrote: [....] See graph below from a tp4056 charger trying to charge a cell that wont hold capacity

As is typical for unhealthy cells, it has very high IR, so you can't fully charge it without lowering the termination current - it probably needs 10mA (vs. above 125ma). So set the charge current to 100mA (since the TP4056 uses C/10 termination). 

It looks like the cell has huge IR (> 1.5 ohms) when near full, assuming TP4056 restarts charging at 4.00V. Normally IR increases when near full, but not to such a huge value for healthy 18650's (except at very low temp's).

What type of cell is it?  Do you have the corresponding voltage graph, or do you know the resting voltage at charge start, and the IR and capacity?
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#6
(07-17-2020, 02:49 PM)gauss163 Wrote:
(07-17-2020, 11:39 AM)fisht99 Wrote: [....] See graph below from a tp4056 charger trying to charge a cell that wont hold capacity

As is typical for unhealthy cells, it has very high IR, so you can't fully charge it without lowering the termination current - it probably needs 10mA (vs. above 125ma). So set the charge current to 100mA (since the TP4056 uses C/10 termination). 

It looks like the cell has huge IR (> 1.5 ohms) when near full, assuming TP4056 restarts charging at 4.00V. Normally IR increases when near full, but not to such a huge value for healthy 18650's (except at very low temp's).

What type of cell is it?  Do you have the corresponding voltage graph, or do you know the resting voltage at charge start, and the IR and capacity?

Not sure what type of cell this was, I generally don't proceed with any further testing and recycle these ones as they don't hold charge.

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