Hello everyone I need some help please.
About 2 years ago I purchased two 18650 batteries and read that the best way to charge them was to use the TP4056 charging module, that's what I have been doing and everything has been fine.
The problem I have now
I have just purchased 2 more 18650 batteries from a different seller and I assumed that they were all the same.
I attempted to charge them as usual with my TP4056 module but after 7 hours they had only reached 3.93v?
(The new batteries are very slightly bigger) I just cant understand why I can charge my older batteries, but my new ones are taking far longer? maybe I need a dedicated charger?

I have attached details of my new battery & also a pic of my old GTL Battery
Thank you very much
John...

 

How many volts of two older batteries when they completed the charge?

You could discharge the new batteries down to 3.2V and charge it again, and measure the voltages after they completed the charge.

The output charging current of TP4056 is 1200 mAh and the current of 18650 is 3400 mAh, the charing time is
Tch = 3400 mAh/1200 mAh = 2.83 hrs
So you may charge it as 3 hours and to measure the voltage of batteries.

There is another specification more like 18650.

 

The battery in your picture is GTL ....I'm not familiar with this , but it's probably a cheap chinese brand ... these are probably not new cells ... used laptop batteries are shipped off to china broken open , and the cells extracted , any which 'hold charge' are given a metal cap on each end to hide the spot welding marks (this results in a longer cell ) given a new plastic sleeve , and sold as new !!!

The cell is probably nearly dead and won't charge above 3.93V ... to check take off the end caps with a sharp knife ( this will not damage the cell) if you see 4 small marks on each end , these are where it was spot welded to make the lap top battery ...

Try to get old laptop or other Li-ion batteries , easily broken open and most 18650 cells inside have years of use left in them.

 

The battery in your picture is GTL ....I'm not familiar with this , but it's probably a cheap chinese brand ... these are probably not new cells ... used laptop batteries are shipped off to china broken open , and the cells extracted , any which 'hold charge' are given a metal cap on each end to hide the spot welding marks (this results in a longer cell ) given a new plastic sleeve , and sold as new !!!

The cell is probably nearly dead and won't charge above 3.93V ... to check take off the end caps with a sharp knife ( this will not damage the cell) if you see 4 small marks on each end , these are where it was spot welded to make the lap top battery ...

Try to get old laptop or other Li-ion batteries , easily broken open and most 18650 cells inside have years of use left in them.

Hello thank you very much for your quick reply.
I found it very interesting to read your comments, Thanks again... John..

 

How many volts of two older batteries when they completed the charge?

You could discharge the new batteries down to 3.2V and charge it again, and measure the voltages after they completed the charge.

The output charging current of TP4056 is 1200 mAh and the current of 18650 is 3400 mAh, the charing time is
Tch = 3400 mAh/1200 mAh = 2.83 hrs
So you may charge it as 3 hours and to measure the voltage of batteries.

There is another specification more like 18650.

Thank you for your quick reply.
I am going to keep a note of fully charged voltage and the time taken to reach this point, and then compare the old and new batteries.
Once again, thank you very much for your help.
John...