all my PCB batteries dont protect for overcharge

I tested my protected batteries today, after they started to charge at 4.35V when I had wrong default voltage selected on charger

- Panasonic NCR18650B
- Samsung ICR 18650-26F
- Keeppower 14500 800mAh
those 3 types does not cut off at all, tested up to 4.5V (around 1.5A for 18650)

I read everywhere that the PCB have overcharge protection inside
The cells are all for sure no fakes, they shut off overdischarge and short circiut and reach the nominal capacity

I disassembled one of my Protected NCR18650B ant there is a 2+1 chip PCB inside

You must be buying from the guy on the corner, who's cuttin' his stuff with baby laxative?

I think I've read from HKJ, or others, the the Seiko cuts off at 4.30v.

Chris

ChrisGarrett said:

You must be buying from the guy on the corner, who's cuttin' his stuff with baby laxative?

I think I've read from HKJ, or others, the the Seiko cuts off at 4.30v.

Click to expand...

It is a DW01 in that protection, it is supposed to cut at 4.30V.
Seiko exist in many different versions with different voltages.

HKJ said:

It is a DW01 in that protection, it is supposed to cut at 4.30V.
Seiko exist in many different versions with different voltages.

Click to expand...

Thanks for the clarification.

Chris

I did torture an old probably half dead Ultrafire battery with the salvaged PCB soldered to it
to get a real cut off voltage of that PCB and the charger
everything worked fine it cut off instantly at 4.32V#

But Taking another Panasonic Cell in the charger it shows 4.36 and it doesnt cut of
Its really odd when I measure 4.21V on the cell the charger shows 4.2V very low current,
when it shows 4.36V I measure only 4.30V at the cell as it seems to have internal voltage drop so the PCB is not triggered until the charge current gets very low

In the end the charger and voltage drop on my adjustable PSU spooked me

Taking it on a PSU I can get without any problem voltages up to 4.33-4.34V then it shuts off
the chip is rated 4.3+/-0.05V

I found out, that my charger has only the copper rail at the back to bypass the spring and the positive was iron not copper

So I bypassed the Spring like in the Nitecore chargers additionally with a copper wire
and did the same with the positive contact

Now the charger reads out the correct voltage almost no voltage drop anymore

HKJ said:

Lexel said:

I tested my protected batteries today, after they started to charge at 4.35V when I had wrong default voltage selected on charger[...]

Click to expand...

It is a DW01 in that protection, it is supposed to cut at 4.30V. [...]

Click to expand...

If it is indeed a DW01 then the datasheet says the overcharge protection trips at 4.30V ± 0.05V, see below. So tripping at 4.35V is within spec.