What are battery cycles and what do they mean?
Here is a short description for you.
A charge cycle is a process of charging a rechargeable battery and discharging it as required by a load.
The term is typically used to specify a battery's expected life, as the number of charge cycles affects life more than the mere passage of time.
Discharging the battery fully before recharging may be called "deep discharge"; partially discharging then recharging may be called "shallow discharge".
In general, the number of cycles for a rechargeable battery indicates how many times it can undergo the process of complete charge and discharge until failure or it starting to lose capacity.
So what this means is, the deeper you discharge your batteries, the less life you will get from them.
Batteries are usually rated to 50% DOD (Depth of discharge).
So, for example, the typical UPS battery has 150 to 250 cycles to 50% DOD. Which in battery backup situations is enough to last a few years, as the frequency of power failure is low.
A Solar battery should have at least 1200 cycles to 50% DOD. As batteries in a solar application will be used on a daily basis. This will cause the batteries with lower cycles to die faster.
Cycles are not the only factors that determine battery life.