Constant-potential charge

Constant potential charging or constant current charging with a voltage cut-off at 1.65 V to prevent the formation of soluble Mn (VI) species may be used. Specially designed chargers, which permit a rapid, optimized cycle, use 5Q-60 Hz current pulses and monitor the OCV during the current... 

Constant potential charging is not recorrunended as the system has a tendency to go into thermal runaway. A modified constant voltage with a current limit is... 

FIGURE 23.49 Typical charger and battery characteristics for constant-potential charging of lead-acid batteries, (a) Constant-potential charging, (h) Modified constant-potential charging. From Ref. 10.)... 

Constant-potential charging is not recommended for sealed nickel-cadmium batteries as it can lead to thermal runaway. It can, however, be used if precautions are taken to limit the current toward the end of charge. 

FIGURE 36.15 Constant-potential charging of AA-size rechargeable zinc/alkaline/ manganese battery at 20°C. Courtesy of Battery Technologies, Inc.)... 

Conslant-current charging is recommended for silver-cadmium batteries, with a charge rate of one-tenth nominal capacity to 1.65 V/cell or 1.55 V/cell minimum. Alternatively, constant-potential charging can be... 

When carrying out constant-potential charges/dis-charges in cyclic use, the battery should be charged at a maximum of 2.5 V/cell. Charging current can be monitored and cut off when the voltage reaches the required value as indicated in Table 45.2. 

Constant-potential charge has always been used as a rapid-charge system for open and semi-open types of nickel-cadmium cell. This type of charge applied to scaled nickel-cadmium cells without precautions has almost always led to the destruction of the batteries. Tn fact, the voltage of sealed cells diminishes after the end of charge and the effect of this is to increase the charge current to proportions that are not acceptable to the batteries. It is possible, however, to use a simple means to charge sealed cells at constant potential... 

Many applications, however, require operation in environments from extreme cold to extreme heat. When batteries are likely to reach temperatures outside the 0-40°C range a temperature compensator built into the charger, operating on 4mVrC per cell based on 25°C is desirable. Constant-potential charge voltages for various battery temperatures and modes of service are shown in Figure 45.5. 

Constant potential Charging method that applies a fixed voltage to a cell often abbreviated to CP. 

Float charging The use condition of a storage battery wherein charge is maintained by a continuous, long-term constant-potential charge. 

Thermal runaway A condition whereby a battery on constant-potential charge at elevated temperature will destroy itself througli internal heat generation, which is caused by high overcharge currents. in constant-potential charging. 

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