# What is the meaning of a battery's "cycle life?"

I started to read about batteries, I am interested in lithium batteries, I found a description regarding the stability and capacity/weight, but I read some unclear descriptions like "cycle."

What does "cycle life" mean? What are the charge/discharge numbers? What if the battery is discharged to 60% and then charged to 80%, Does this count as a cycle?

The cycle life is the number of complete charge/discharge cycles that the battery is able to support before that its capacity falls under 80% of it's original capacity. So if the battery is discharged to 60 % and then charged to 80% it isn't a complete cycle.

You could find more information in this site. Your link says that cycle life is the number of charge/recharge cycles that the battery can support before that it's capacity falls under 85%, my link says 80%. These datas are indicative and I think that can vary a little bit. Generally cycle life means the number of charge/recharge cycles before a battery starts to reduce visibly its performance.

According to your link the Li Po batteries generally can support 600 full charge/recharge cycles before its capacity falls under 85-80%. Remember that this value is only indicative and this number can vary a lot depending the manufacturer and the product quality.

• *Under ideal conditions in a lab dedicated to calculating cycle life. NOTE: Aging usually causes as much if not more degradation of a li-ion battery than battery cycling. Commented Jun 20, 2014 at 18:16
• I'm replying to an old answer, but your answer is the closest to my own question. If I have a lead-acid battery that can do 600 cycles to 50% DoD (eg Victron 220Ah AGM, victronenergy.com/upload/documents/…), does that mean that after 600 cycles it has 80% of its original capacity, or after 600 cycles it has 50% of its original capacity?
– izak
Commented Oct 3, 2015 at 7:17

It is simply the number of times the discharge / charging cycles can take place until the maximum charge capacity of the battery is reduced to 85 % of its charge capacity it had when it was made

The cycle life will also vary based on the conditions the battery is in. Factors such as temperature, movement, how frequently it is used, etc. For example, lithium polymer batteries function best in moderate temperatures because that is when the gel is at the optimum density to be fluid and still retain its conductivity. But heat it up too much, it becomes less dense, swelling up and reducing how conductive the it is, and how long it retains a charge. The advertised cycle life is how the battery perform under ideal conditions only, which any kind of battery rarely sees.