Many salvaged 18650 cells from used laptop batteries are unusable due to them not being able to take a charge as they are at 0v. But there is a way to recover them. These cells have had their protection fuse popped which disconnects the positive battery terminal. Usually the fuse triggers when the battery pack gets to hot which can be the case with some laptops. Once recovered the cells are usually just fine.
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Step 1: Finding the Cells
The cells that can be recovered should look like this:
1. The cell holds no voltage
2. There is no rust on the cells. (If you see rust that means the electrolyte has leaked out and the cell cannot be used. The green cells shown in the picture has dots of rust underneath it and means that it cannot be used.)
3. Smell the top of the cell. If there is a sweet smell that means the electrolyte has leaked and the cell cannot be used anymore.
4. The cell should have no visible defects.
5. There is no continuity between the positive terminal and the negative terminal.
Step 2: Separating the Cells
Separate the cells by peeling off the metal tabs.
As you can see the cell reads 48mv this means that the cell is at 0v.
Step 3: Fixing the Cells
- Bend a paperclip
- Push the paperclip into the top of the cell
- Carefully push the paperclip down. If a hiss is heard than the cell may not be usable anymore as the seal is broken.
- If you had done it right and no hiss is heard the cell should now be showing voltage.
The cell no longer has a working fuse so do not stress the cell too much
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