How to check if a salvaged 18650 cell is good

XTAR Light

Enlightened
Vendor
Joined
Apr 26, 2010
Messages
716
Location
China
Some customers told us, they use xtar chargers to savage the 18650 cells from their old notebook packs, laptops, scooter battery packs...Some good cells could be retrieved and reused for different applications again. It needs to check them first to ensure they are safe and working well.

There are some steps to help you assess the condition of a 18650 cell:

*Visual Inspection: Check the physical condition of the battery. If the cell looks undamaged, it's likely the cell is still in good condition. Any noticeable deformation, leaking, rusted, or corroded surfaces are the indicators of bad cells and should be disposed of properly.

*Voltage Test: Use a multimeter or xtar charger to test the cell's voltage. If the cell voltage falls within the 2.6V to 4.2V range, it's a good sign that the cell hasn't been over-discharged. Generally speaking, if the voltage is below 2.5V, the cell is damaged to some degree.

*Internal Resistance Test: IR can indicate the health of a cell. Lower IR is generally a sign of a healthier cell. It can use a internal resistance meter, or charger with IR testing function to check it. A healthy 18650 cell would have a IR of below 100 mOhms.

*Charge Test: To properly charge the cells with smart 18650 Li-ion battery charger. As you don't know the condition of the cell, it's suggested keep low charge currents. If the cell gets very warm during charging, then it may have a serious internal short and should be discarded.

*Capacity Test: It involves discharging the cell and measuring its total capacity. It can check if the battery's capacity has significantly degraded. Some xtar chargers with Grade function can test the cells' capacity. If the cell only holds 80% or less of what it used to be able to do, then it's time to recycle it.

*A Load Test: If the battery voltage remains stable during a load test, then it typically means that the cell is doing ok and can perform as expected.

*About Self-Discharge: Leave the battery unused for a period (e.g., a week) and then measure its voltage. Healthy batteries should retain their charge fairly well, while damaged or aging batteries may have significant self-discharge.

Measuring the cells' internal resistance, capacity, and other parameters can give a comprehensive assessment. After all of these tests, good cells can be salvaged again. As for damaged cells, it's suggested to dispose of them properly at a recycling center or hazardous waste facility.
 

Monocrom

Flashaholic
Joined
Aug 27, 2006
Messages
20,479
Location
NYC
Fantastic advice. Though a certain brand out there sells good quality 18650 cells for literally $7.oo each. Brand new. Sure, there are some 18650s pushing near the $20.oo mark for one new battery. But not all of them.
 

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