Battery With Internal Resistance

带内阻的电池

When a battery fails, it is typically because it has built up enough internal resistance that it can no longer supply a useful amount of power to an external load. If you measure the voltage of a failed battery which is disconnected, you will usually find that it has a nearly normal voltage, so that a voltmeter is not a useful tool to judge the degree of life left in a battery. If you connect the battery to an external resistance, then you will find that the terminal voltage of the battery drops; this can be interpreted as dropping most of its voltage across its internal resistance so that it is not available for external service. The following example allows you to explore the effects of internal resistance.

当电池失效时，通常是由于其内部电阻增加到足以使其无法为外部负载提供有用的功率。如果你测量一个断开的失效电池的电压，通常会发现其电压接近正常，因此电压表不是判断电池剩余寿命的有用工具。如果你将电池连接到外部电阻，你会发现电池的端电压下降；这可以解释为电池大部分电压降在内部电阻上，因此无法为外部使用提供电力。以下示例允许你探索内部电阻的影响。