A charge cycle is a complete charge and discharge on a rechargeable battery. People use a charge cycle on a battery every time they drain a battery while powering a device, the battery having been charged before use or purchase. The number of charge cycles a rechargeable battery can withstand before performance degrades is the accepted method of measurement for rating rechargeables charge cycles. The number of charge cycles, voltage and battery life (milliamp hours) are all important performance ratings for rechargeable batteries. A charge cycle can be a complete full charge to discharge or a series of partial drains adding up to the battery's capacity. Depending on the type of rechargeable battery, the number of charge cycles varies greatly, as does battery life. Also, some types of rechargeables such as nickel cadmium develop a memory effect if they are not discharged completely before recharging, reducing the longevity of future charges