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constant current constant voltage (accu) (CCCV)

Chargers have different charging procedures adapted to the charging characteristics of rechargeable batteries. This adaptation concerns the chemical conversion, where certain criteria must be observed to avoid damaging the batteries. Some batteries cannot tolerate overcharging, others must be charged slowly at constant current, and still others must be deep discharged briefly before charging to reduce the memory effect.

The IU charging method used for lithium-ion batteries and lithium-polymer batteries uses constant current and constant voltage, Constant Current Constant Voltage (CCCV). In this process, the batteries are first charged with a constant current. This limits the charging current and prevents excessive charging current in the initial phase. Constant current charging continues until the end-of-charge voltage is reached. This value is reached at about 70 % to 80 % of the nominal capacity. Subsequently, charging is continued at constant voltage, so that the end-of-charge voltage cannot be exceeded. The charging current decreases as the charge increases.

Charging method with two different constant voltages (IU0U)

Charging method with two different constant voltages (IU0U)

Another charging method starts with a constant current charge followed by a constant voltage charge, as in the IU method. However, in this method, the constant voltage is abruptly reduced to a lower voltage value after a certain time. The time sequence is constant current (I), constant voltage with end of charge voltage (U0) and reduced constant voltage (U): IU0U. In this method, the voltage in the first constant voltage phase can be higher than in the IU method, resulting in a shorter charging time.

IU charging method (CCCV) with constant current and voltage

IU charging method (CCCV) with constant current and voltage

IU charging methods are used in lead-acid batteries, lead-fleece batteries, lithium-ion batteries( LiIon) and lithium-polymer batteries( LiPo).

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Englisch: constant current constant voltage (accu) - CCCV
Updated at: 15.02.2018
#Words: 270
Links: conversion, constant, current, memory effect, charging method
Translations: DE
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