Recovering a discharged Li-ion

[KurtS]

I have a Li-ion battery that got fully discharged (the phone shop left the phone hooked up to the computer and ran down the battery). It's a 3.7 v nominal battery and it's at 3.3 volts. It looks like the phone is trying to charge at 4.2v. The battery seems to come back some (about 3.65) after charging some time, but not enough to turn on the phone.

So, what's the procedure for getting a battery back to operational voltage? These voltages are close to my 18650 charger (I'm in Costa Rica with my little ML-102), so that may be an option (though the connections will be problematic).

Any insight it appreciated.....

Thanks!
Kurt

 

[Trevtrain]

Hi Kurt

I assume you are testing the voltage with a multimeter rather than some kind of built-in phone utility?

AFAIK, phone batteries should have some kind of protection circuit to prevent discharge to unsafe levels so not sure that the phone shop "running it down completely" should have caused a problem. It sounds more to me like the charging circuit in the phone or the power supply might be at fault (unless the battery is really old.) How long have you been waiting for it to charge?

Can you tell us what it was in the shop for?

Many newer phones charge via USB so connecting them to the computer would actually charge them rather than the opposite. Is this an older model phone? Can you tell us the brand or model and how long you've had it?

It is possible to charge the phone battery with a regular charger but rigging up something to connect to the contact points can be very fiddly. You also need to be aware of charge currents as you don't want to charge it at too high a rate.

Personally, I'd start by going back to the phone shop (if that's possible) and seeing if they could test another battery and/or power brick.

 

[Turbo V6 Camaro]

I have a Li-ion battery that got fully discharged (the phone shop left the phone hooked up to the computer and ran down the battery). It's a 3.7 v nominal battery and it's at 3.3 volts. It looks like the phone is trying to charge at 4.2v. The battery seems to come back some (about 3.65) after charging some time, but not enough to turn on the phone.

So, what's the procedure for getting a battery back to operational voltage? These voltages are close to my 18650 charger (I'm in Costa Rica with my little ML-102), so that may be an option (though the connections will be problematic).

Any insight it appreciated.....

Thanks!
Kurt

USB will only charge at max 500ma (usally less somtime only 100ma) depend on the phone and the usb "handshake"

if my phone get so dead the protect turns off the phone, only my wall charger can bring it back, witch is 1000ma (1A)

if you are using the wall charger then like said above it could be faulty, if not the battery might just be dead.