[Help] Charging non-removable phone battery.

cesedy · January 1, 2021

Hi.

I have a phone which will not charge. But I need the battery charged enough to copy data out of it.

I have a bench PSU, and I would like to charge the battery with 5v 0.5A.

When I got to the battery, I got confused to which pins to connect for charging. Maybe anyone could tell me to which I should connect?

Here are some pics:

1. This is a picture with the pins. As I understand they are:

1. P+ (goes to phones battery connector)

2. P- (goes to phones battery connector)

3. +?

4. -? (goes to phones battery connector)

2. Here are voltages between pins 4 & 3 (now the voltage between these pins have dropped to 2.19V)

3. Here are voltages between pins 4 & 2 (now the voltage between these pins have dropped to 1.57V)

4. Here are voltages between pins 4 & 1 (now the voltage between these pins have dropped to 2.19V)

5. The voltage between pins 1 & 2 while disconnected from battery connector

6. The voltage between pins 1 & 2 while connected from battery connector

So, to which pins I should connect the terminals to charge the battery?

Thank you.

Electronics Wizardy · January 1, 2021

3 minutes ago, cesedy said:

I would like to charge the battery with 5v 0.5A.

Don't do this, bateries are pretty picky about how they are charged, and that battery could go boom if charaged at 5v.

Really, don't do this, this won't end well, get another batteries, power it via usb charging, or get someone that knows what their doing here.

cesedy · January 1, 2021

25 minutes ago, Electronics Wizardy said:

Don't do this, bateries are pretty picky about how they are charged, and that battery could go boom if charaged at 5v.

Really, don't do this, this won't end well, get another batteries, power it via usb charging, or get someone that knows what their doing here.

A bit too expensive to buy a new battery for 10mins I would use it.

If 5V is the concern, I can charge with lower voltage as well (but would not the mA be the most dangerous part?).

Electronics Wizardy · January 1, 2021

4 minutes ago, cesedy said:

A bit too expensive to buy a new battery for 10mins I would use it.

If 5V is the concern, I can charge with lower voltage as well (but would not the mA be the most dangerous part?).

Can you take out the battery to find the wiring, those extra pins are likely for the protection circuit on board.

Id rally not mess with batteries from what you seem to know, they like to go boom if mistreated

mariushm · January 2, 2021

No, DO NOT put 5v anywhere.

You have a lithium battery which has a "default" voltage of 3.7v and charges up to 4.2v ... if you put more than that on the battery it will probably smoke and burn.

The flex strip from battery to the phone most likely has more than 2 wires/contacts. It will have negative, positive and probably a temperature sensor wire which is used to make sure the battery's temperature doesn't go above some threshold when it's being charged by the phone's charger IC.

The battery should also have a protection IC hidden inside.

If you don't have a soldering iron or something like that... I'd suggest getting and adjustable linear regulator chip like LM317 or some adjustable power supply and configure it to output around 4v and then connect the wires on the flex strip on the negative and positive ... should be the widest copper traces. You can disconnect the flex strip from the phone, carefully scratch the flex strip with a knife or something and put a thin wire over the exposed copper and use some electrical tape or something for temporary connection.