usable life meaning in English

可用时间
适用期

Under normal use rechargeable batteries have a usable life of between 250 - 500 recharge cycles ( depending on the type used )
任何电池都具有有限的寿命，无论它具有多大的能量。可充电电池跟普通电池没有什么区别，除了它可以进行有限次数的充电外。
The practice shows that method can effectively protect boiler and deoxidizer , consequently decreases maintenance cost and prolongs usable life of the equipment
实践证明，在除氧器内加药能够对锅炉和除氧器进行有效保护，从而减少维护费用，延长设备使用寿命。
The department is a stern supporter of the measure taken by the electrical and mechanical services department to replace conventional rear tyres of heavy and medium vehicles with retreaded ones in order to reuse resources and lengthen the usable life of tyres
本处亦全力支持机电工程署的措施，在更换重型和中型车辆的传统后呔时，装上翻新轮呔，使资源可循环再用，并延长轮呔的使用期。