Recovered a Li-Ion discharged to zero

So I got this extended battery for my phone - it's Li-Ion so all of the essential facts and attributes of it work exactly the same as 18650s and such, it's just flat and square.

I got it and the phone said it's at 0%. Now I realize the % in the phone is an 'idiot gauge' and doesn't tell you the voltage, I don't think 0% in the operating system translates to 0V. It may have been 2.5V or such. The voltage at which the phone shuts off. Anyway, I recharged it and it recovered nicely. And keeps working without visible anomalies. I should have taken a voltage reading before I recharged to determine the voltage it was at.

I don't remember recovering 18650s and such discharged to 0V, and if I did, they didn't held charge.

The other factor I don't know is how long it has been in the discharge state. Should I complain to the seller?

The battery probably has protection circuits built in, causing it to cut off once it reaches a certain discharge voltage.

Now you say the phone said it was at 0%. Was this with the battery powering it, or when you connected it to a charger? If the battery was powering the phone and it said 0%, it still had enough charge to power up the phone. If it was when you plugged it in, it was at or below the voltage the phone considers to be 0%, which isn't zero volts.

If the battery had been discharged to 0V for real, it would be dead, probably unable to take a charge at all, at least not without overheating.

In reality it was probably just discharged to something like 2.5V or whatever the threshold the phone considers to be 0%.

Does the battery seem to be working normally now? Is it holding a charge ok, and is it discharging at a normal rate relative to phone usage?

Does the battery have external positive and negative contacts, that you can probe with an actual voltmeter ?

These are often "hidden" or shrouded, to reduce the chance of an accidental short circuit.

Yeah, I wouldn't worry. The battery-pack makers build in overhead with the BMS. And it's likely the BMS wouldn't allow the battery to be charged at all, if a cell had dropped down into dangerous territory.

That said, it's certainly not good for a lithium-ion cell to be sitting around 2.5v for an extended amount of time, but it's not much different than keeping it fully charged all the time, and most people do that.

kpatz said:

or when you connected it to a charger?
Does the battery seem to be working normally now? Is it holding a charge ok, and is it discharging at a normal rate relative to phone usage?

Click to expand...

Device off, connected to the charger and it said: 0% and started charging. So obviously it wasn't at 0V. I don't know what voltage the operating system considers to be 0%. Percentage is kind of meaningless, because like in the case of 18650s and 18500s and so on, fully charged is about 4.3V and fully discharged is about 2.5V.

Everything works fine and it holds a charge, I just cannot figure out if it took any damage from that, but I have another battery just like it I got new and they seem to be operating similarly.

archimedes said:

Does the battery have external positive and negative contacts, that you can probe with an actual voltmeter ?

These are often "hidden" or shrouded, to reduce the chance of an accidental short circuit.

Click to expand...

Yeah they do, because the contacts have to connect to the contacts in the device itself. It's a rare phone that has a removable battery. Usually you don't get that luxury.

It's a ZeroLemon 10,000 mAh extended Li-ion battery - the stock is about 3200 mAh and nowhere near enough for the device.