Lithium Batteries Removal and Project

[DW1961]

I have a couple of higher end enthusiast mechanical keyboards that were replaced by the vendor. They were defective right out of the box, so the battery in them is brand new, A couple are 2900mAh and so forth.

Instead of just tossing out the entire board, I'd like to save the batteries for other projects, and actually to fit two into one keyboard enclosure.

My question is How do I know when the battery is fully charged once it is disconnected from the keyboard electronics?

[ledtester]

What do the batteries look like? Post a photo!

My question is How do I know when the battery is fully charged once it is disconnected from the keyboard electronics?

For a single lithium-ion cell the magic number is around 4 volts. Dave did a video on what charging a single cell entails:

EEVblog #919 - How To Charge Li-Ion/LiPo Batteries With A Power Supply
https://youtu.be/jNmlxBXEqW0

... and actually to fit two into one keyboard enclosure.

Are you planning to use them in parallel or series?

[DW1961]

This is the only image I have of the battery in one board. The other is similar, but I'll have to open them up and extract them in order to see if they have any ID on them. It's teh flat black thing in the middle of the bottom of the board.It connects to the board with a small JST connector and two wires.

[ledtester]

When you open it up see if it has any protection circuitry like in this pic:

[DW1961]

OK I will. Thanks.

[DW1961]

When you open it up see if it has any protection circuitry like in this pic:

(Attachment Link)

I just got around to removing this battery. This is what it looks like:

[sleemanj]

Standard protection circuit.  DW01 protection IC and 8205A dual mosfet pair, or work-alikes.

[DW1961]

Standard protection circuit.  DW01 protection IC and 8205A dual mosfet pair, or work-alikes.

So that means it has over charge protection? Can I run two of those in Parallel and leave both protection circuits?
 

[sleemanj]

Yes

[TheNewLab]

If it is a dead battery, I have a particle meter with a unique packaged Lith-ion battery. Could not find a replacement anywhere. Cracked upon the plastic case, de-soldered the Lith-ion batt packet, and soldered on a new battery to the little control circuit-PCB. Was a bi..h to do it so tiny, but it worked

[DW1961]

If it is a dead battery, I have a particle meter with a unique packaged Lith-ion battery. Could not find a replacement anywhere. Cracked upon the plastic case, de-soldered the Lith-ion batt packet, and soldered on a new battery to the little control circuit-PCB. Was a bi..h to do it so tiny, but it worked

That's a good idea. The battery is brand new. It was a bad 60% mechanical keyboard, and the vendor didn't have me send it back. That particular board is NOT getting the upgrade. It's too hard to break down the case w/o breaking the mode switch.

My other board is an 87 key and it's only a 2000mA battery. I also got a replacement for that one (dead switch socket) w/o having to return the defective board. I have not taken that one  apart, but it's easy with no small and delicate parts. I just have to get around to tearing it down and seeing if it is large enough in the pan to accept two of the original 2000mA batteries. If it is, then I have to decide if I want to buy a larger one (around 15-20 dollars) or run both original 2000mA batteries in parallel. But I gotta say, I can get a 3.7V 5000mAh Battery for 15 bucks. Still, if both bats fit, I'll solder them up.