Introduction: DIY PowerBank From Old Laptop Batteries
Most of the times the first thing which gets damaged from your laptop is the battery and in most cases, only 1-2 cells may be faulty. I have a few batteries from old laptop lying on my table, so I thought of making something useful out of it
Step 1: Components and Tools Required
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- Batteries from old Laptop / 18650 Batteries
- 18650 Battery charger module / Powerbank module / JX-887Y (Any compatible one)
- Nose Pliers
Step 3: Determine Current/Voltage Requirement
Check this simple illustration to understand, how to arrange batteries to increase voltage or gain higher capacity.
- Adding cells in a string increases the voltage; the capacity remains the same
- Faulty cell 3(Red) lowers the voltage and cuts the equipment off prematurely.
- With parallel cells, capacity in Ah and runtime increases while the voltage stays the same.
- A weak cell will not affect the voltage but provide a low runtime due to reduced capacity. A shorted cell could cause excessive heat and become a fire hazard. On larger packs, a fuse prevents high current by isolating the cell.
- Parallel/Series configuration provides maximum design flexibility. Paralleling the cells helps in voltage management.
Step 4: Separate the Cells
Using screwdriver and nose pliers (or any useful tools) remove the battery pack plastic enclosure without damaging any cells. Here is a good video which shows how to open laptop battery without damaging the cells
- Remove the connection from the BMS board and separate each cell, Normally there will be 6 cells (3 cells in 2 row).
Warning: Be careful while doing this, some of the cells might be full charge. accidental short-circuiting may result in damaging the cell.
In my case, I had 6 18650 Li-Ion batteries. The capacity was 2200mAh. If you are unaware of the capacity just google the model number on the cell, it would be something like US18650VTC6
Step 5: Identify Good Cells
- Mesure each cell voltage using a multimeter, if the voltage is less than 2.5v even after charging, then it’s not a good cell
- If any of the cells are getting hot during charging then remove that cell
Step 6: Circuit
Step 7: It's Done
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