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

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• Batteries from old Laptop / 18650 Batteries
• 18650 Battery charger module / Powerbank module / JX-887Y (Any compatible one)
• Multimeter
• Nose Pliers
• Screwdriver

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.

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

• 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