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The C-rate is defined as the charge or discharge current divided by the battery's capacity to store an electrical charge. While rarely stated explicitly, the unit of the C-rate is h −1 , equivalent to stating the battery's capacity to store an electrical charge in unit hour times current in the same unit as the charge or discharge current.
For example, consider a battery with a capacity of 200 Ah at the C 20 rate (C 20 means the 20-hour rate – i.e. the rate that will fully discharge the battery in 20 hours – which in this case is 10 A). If this battery is discharged at 10 A, it will last 20 hours, giving the rated capacity of 200 Ah.
Depth of discharge (DoD) is an important parameter appearing in the context of rechargeable battery operation. Two non-identical definitions can be found in commercial and scientific sources. The depth of discharge is defined as: the maximum fraction of a battery's capacity (given in Ah) which is removed from the charged battery on a regular basis.
In a battery electric vehicle (BEV), the state of charge indicates the remaining energy in the battery pack. [4] It is the equivalent of a fuel gauge.. The state of charge can help to reduce electrical car's owners' anxiety when they are waiting in the line or stay at home since it will reflect the progress of charging and let owners know when it will be ready. [5]
Rates up to three times normal charge rate (defined as C, the current equal to the nominal capacity of the battery divided by 1 hour) can be employed for periods of 30 minutes. [18] Fully charging a NiFe cell consists of seven hours at the normal cell rate. In service the amount of charge given is governed by the extent of the previous discharge.
Trickle charging is the process of charging a fully charged battery at a rate equal to its self-discharge rate, enabling the battery to remain at its fully charged level. This state occurs almost exclusively when the battery is not loaded, as trickle charging will not keep a battery charged if current is being drawn by a load.
Under certain conditions, some battery chemistries are at risk of thermal runaway, leading to cell rupture or combustion. As thermal runaway is determined not only by cell chemistry but also cell size, cell design and charge, only the worst-case values are reflected here. [64]
A charge controller, charge regulator or battery regulator limits the rate at which electric current is added to or drawn from electric batteries to protect against electrical overload, overcharging, and may protect against overvoltage. [1] [2] This prevents conditions that reduce battery performance or lifespan and may pose a safety risk. It ...