The internal series resistance of a battery determines the maximum discharge current of the battery. Consequently, for applications in which the batteries are required to provide high instantaneous power, the internal series resistance should be low. In addition, the series resistance will effect the battery's efficiency but may change as the battery ages. (DEFINE WHERE INTERNAL SERIES R COMES FROM.)
Self-discharge refers to the fact that even in the absence of a connected load, the discharge reaction will proceed to a limited extent and the battery will therefore discharge itself over time. The rate of self-discharge depends primarily on the materials involved in the chemical reaction (i.e., the type of battery system) and on the temperature of the battery.
The maximum amount of current a battery can provide for a short period of time is called the cranking current. This parameter is often specified for transport applications, in which the battery must provide enough current to start a large engine. However, it is typically not an important parameter in PV systems.
The temperature sensitivity and temperature range over which batteries can be operated depend on the type of battery and the state of charge of the battery. All batteries lose capacity as the temperature is reduced. Some types of batteries are sensitive to freezing and suffer irreversible damage if they are frozen.