How to Check if a Recycled 18650 Battery is Good or Bad

18650 batteries are rechargeable lithium-ion cells that power many devices like laptops, flashlights, power tools, and electric vehicles. They can be recycled and reused for different applications, but you need to check them first to ensure they are safe and working.

There are two main methods to check a recycled 18650 battery: using a multimeter or using a battery tester. A multimeter is a tool that measures voltage, current, and resistance. A battery tester is a tool that measures capacity, internal resistance, and discharge rate.

To check a recycled 18650 battery using a multimeter , you will need:

A multimeter, a resistor,alligator clips,a stopwatch

Here are the steps:

Set the multimeter dial at the battery checking level and attach the clips to the probe tips.

Pick a resistor that matches the battery’s voltage. For example, if your battery has 3.7 volts, you can use a 10 ohm resistor.

Reset your stopwatch and connect one end of the resistor to the positive terminal of the battery.

Set the multimeter knob to show direct current (DC) and connect its positive probe to the other end of the resistor.

Connect its negative probe to the negative terminal of the battery and start your stopwatch.

Read the current value on your multimeter screen and write it down.

Stop your stopwatch when your battery voltage falls below 2.6 volts or after one hour (whichever comes first).

Divide your current value by 1000 to get milliamps (mA) and multiply it by your stopwatch time in hours to get milliamp-hours (mAh). This is an estimate of your battery’s capacity.

To check a recycled 18650 battery using a battery tester, you will need:

A battery tester

A holder for four 18650 cells

Here are the steps:

Put your recycled 18650 batteries into the holder slots according to their polarity.

Connect your holder wires to your battery tester terminals according to their polarity.

Turn on your battery tester and choose “Test” mode.

Select “Li-ion” as your chemistry type and “3S” as your cell count (if applicable).

Press “Start” button and wait for your tester to finish its cycle.

Read your capacity value on your tester screen for each cell.

These methods will help you find out if your recycled 18650 batteries are good for reuse or need more recycling.