Lithium-ion battery Cycle

[pier1]

I have a doubt regarding the charge-discharge cycle for Lithium-ion batteries.

If the battery gets discharged to 50% and then charged to full, is it considered as one cycle?

or

if the battery gets discharged fully and gets charged again to full it is considered as one cycle ?

Regards,
Pier

 

[audioguru2]

Go to http://batteryuniversity.com/ to learn about batteries.
A rechargeable Lithium cell is 4.2V when fully charged. Its voltage quickly drops to 3.7V when it is used then drops slowly to 3.0V. Its load must be disconnected when its voltage reaches 3.0V or it is damaged. It must not be discharged to "half" (2.1V).

A cell might be able to be charged when its voltage is too low at 2.5V but its charging current must be reduced until its voltage has risen to 3.0V. A cell that is discharged to a voltage less than 3.0V will have its capacity reduced.

One discharge cycle is when its voltage has dropped to 3.0V.