Get your Hands on to some Old Laptop Battery Pack or any old Rechargeable lithium ion cells .
got these batteries from my 8 year old laptop .
Break the Plastic Casing , Carefully ,
without damaging any cells ( if you use extra force , they could puncture up , leak and catch fire ! )
once you have the cells out of the plastic casing
Cut them away from BMS board and separate them individually .
Clean the terminals properly , so the spot welds are smoothed and not bumpy .
Step 1: Identify the Cells From Labeling
Identify the cells , from the printed labeling on the shrink wrap covering .
in my case they were trusty old Li-ion ICR18650 22H
look up the respective Data Sheets on google .
Get to know the original Manufactured Capacity of those cells.
Study the charging/discharging curves and Capacity cycles .
Also Test the Voltages on them .
label each cell with numbers , and make a table in your notebook .
keep tabs of original voltage at which you found the cell , and take readings for each time you cycle them in charging or discharging .
after charging the cells , keep them away in cold dark place for few days ,
check the voltages on cells in storage after few days , if the voltages dropped significantly , throw the cell away as it is bad and will damage your project .
Step 2: Charging the Cells Using TP-4056 Board .
Tp- 4056 is a great board to charge your batteries of less than 4.2v
look at the spec sheet .
this board is simple to use . plug and play applications .
can be used with a micro USB charger . is capable of charging at maximum of 1 amps
it comes with battery protection for overcharge and over discharge ,
Read the chart which shows how to sort your recycled Li-ion cells on capacity and voltage state.
Step 3: Simplest Way to Discharge & Estimate the Capacity of Cells .
You don't need to Spend a lot of time and money on building a Discharge circuit .
no need of n channel MOSFET and LCD displays .
you just need an Arduino board , a good 5 watt Resistor ( 1 ohm to 22 ohm works fine )
I had both 1 ohm and 22 ohm 5 watt resistors , so tested both.
basic knowledge of P=IV and V=IR
Cell is connected with the resistor and Arduino's Analog pins Read the Voltage drop across the resistor with respect to Time , providing with a rough estimate of the capacity of your cells .
arduino sends output on the serial ports available for viewing on the computer , so you don't need any lcd or logger circuit , the IDE serves as a serial output port , you can print , record and chart your readings and get the capacity value.
If you are building small projects , you can use this circuit to check if your batteries hold any charge .
if you are building a power wall level project , i recommend investing in a proper Capacity tester .
I am using my cells for LED lights as a load for overnight functions and charging in daylight using Solar power , so these batteries were good for this project and over 1.3amp each , after 8 years of usage , i was surprised they could retain even 1 amp and hold the voltages for long time in storage .
Step 4: Don't Forget to Have Fun .
Don't let the unavailability of parts and components to keep you from Recycling and Reusing the batteries .
No Mosfet , LCD , Buzzer , Soldering etc required .
if you happen to get your hands on some old Lithium ion cells , reuse them for small load projects LED lights for garden and outdoors .
anything that requires less than 1amp of consumption old batteries to the rescue .
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Keep Tinkering , DIY life .