Protected 18650, how supposed to work?

Batteries and Chargers Rechargeable Batteries
1

Hello everyone,

how is the protection PCB of a 18650 supposed to work when approaching the over-discharge voltage threshold, for example 2.75V?

Will it trip at any discharge current, 100mA, 500mA, 1000mA?

Once tripped, 0.0V, is it supposed to stay there forever ("dead battery")?

Or is it supposed to untrip automatically after a few minutes to 3.61V?

Let's assume that the protection has tripped and the cell has a permanent 0.0V reading. In such a case, a charger would not be able to recognize that a battery is inserted, would it?

And what would be the perfect algorithm for a charger (not for a human ;) ) to force the untripping of the a tripped protection? — I am guessing either steady low current (how low?) or pulsating high current?

Thanks for some insight!

2

I have a 26650 that is doing that, it was on charge and at 4.12v, the next time I looked the charger (BTC-3100)said null. I removed it from charge and my DMM reads 0v, has the protection tripped and if so how do I get it to reset?

3

Let me ask this way:

How do i get the battery into constant tripped state 0.0V?

I've been discharging several protected cells (Nitecore, Panasonic, Trustfire, Eagtac) down to 2.50V with hobby charger and the protection on my samples don't appear to trip. I can discharge them to 2.50V as if they were not protected.

Basically i want to produce (yes i want!) protected cells with a constant 0.0V reading.

How do i do it? :D

4

You may have to go lower to trip it.

Very low cutrrents may not trip it. How low? Not sure but I believe / hope under 100mA

No. A charger or voltage going into the battery will reset it.

Some charger won’t recognize it and won’t reset protection.

5

PCB often fails man.

The best protection of 18650/26650 is in buying quality charger or maybe in a driver that cuts of at 3A or just bit lower than that.

Protected cells adds additional resistance to current flow. I don't know how, I don't know why but my light meter don't lies.

6

Cheap chinese protection chips are more likely to fail.

7

I notice on my protected King Kongs, on one charger I bought, I have one cell that appears to trip over and over after a bit at 2.0A near 4.1V, and register 0.0, then reset, register 4.1, charge, eventually getting to 4.2V.

8

You can reset a tripped protection circuit by placing the positive end in contact with positive end of a good battery and connecting the negative ends with a wire for a couple of seconds. I have used that method twice to reset tripped pcb’s. Hope that helps!