Another thread about battery cannot charge (protected cells)

Batteries and Chargers Rechargeable Batteries
1

I’ve been very happy with my Keeppower 840mAh 14500 cells

One day I was using it in a sipik clone and used it like normal.
I always use them till a point where protection shuts itself down (and still able to charge it back up)

but just today… it will never charge up more than 3.8v.
never more than 3.8v

Was using fenix are-c2 charger and it ends at 3.8v
maybe it’s too smart to know it’s problematic

so I tried the trick of using 2 cells to awake the sleeping cell

still getting max 3.8v

i tried force charging with a cheapo charger and the protection just won’t allow any current going through.

what should I do? Cells were never below 3.7v every single time I use them

protection circuit is giving odd values of 2.8v and 1.5v to the fenix charger making it think that these cells are fully charged but it always stayed at 3.8v with a DMM test

I hope you guys can help me.

2

Sorry I don't know the answer, but at least if you have a Opus charger, you could do a "refresh"or capacity check (forgot the exact name) that would discharge and charge the cell.. it worked on every liion cell that wouldn't charge otherwise.

You can also keep it in your charger for a very long time.. and check the voltage every hour or so.

Do you have any other charger?

3

Thanks for the quick reply :smiley:

I can do a makeshift charger from powerbanks

I’ll give it a try but I’ll assume it’s the same answer as using my cheapo unbranded china charger

Edit:

Apparently it charges when i force 2.1A into this cell.
now it’s going 3.96V rather than it’s old 3.8V
I’ll update on how it goes later :slight_smile:

4

apparently it doesn’t work… stayed at 3.8v when i switched it off…

and protection circuit kicked in again

new edit

had to tear the cell apart and charge the cell manually then the protection circuit finally worked…

I guess its time to get myself some heatshrink

5

Or just throw out the protection because it can do the opposite without you knowing it. They are great if they work properly but then do as much harm as good.

6

The original post is full of confusion and contradictions.
You said you run your cells down till protection kicks in.
Then you say your cells are never below 3.87 volts.
Then you say the charger reads 1.5 volts and the charger thinks it is fully charged.
Are you sure the charger is not set for NiMH ?

7

protection always kicks in at 3.8v on these cells
so i just left it that way

now it’s fine so far

the fenix are c2 is a smart charger but it can get dumb at times thinking a li-ion cell is a nimh cell. (have a look at the video)
the charger does everything automatic which cause problem at times.

8

Sounds like busted protection circuit. It sees 3.8v as if it’s 4.3v or something then trips the overvoltage protection.