What is the cycle lifetime of lithium ion batteries?

- Nov 28, 2018-

It depends on a variety of factors which will cause parasitic reactions and degrade the life cycle of the cells. Most importantly:

  • Temperature

  • Charge/Discharge Current

  • Charge/Discharge Cut-off voltage

Temperature: Cells are rated differently for charging and discharging. For discharge you may go down to -20 degrees C but will rapidly increase the degradation. Keep above 10 degrees and lower than 60. For charging, must keep above 0 degrees or lithium-plating will occur. The closer to 25 degrees C, the better.

For current, the lower the current the better.

For voltage, partially cycling eg between 3.3 V to 3.8 V will greatly increase cycle life than doing a full cycle of ~2.5 V to 4.2 V.

In many cases you can expect an 18650 lithium-ion cell to reach 500 cycles before reaching 80% of it’s capacity (the international standard to rating cycle life).

However in sub-optimal conditions you may only reach 200 or less cycles.

You may be able to reach more than 500 cycles if you are following optimal conditions.

A lifepo4 cell may reach 1500 cycles before reaching 80% of its capacity rating.

More info on cycling can often be found inside the manufacturers spec sheet for each individual cell