Batteries Constant voltage charging

Charging can be accomplished by various methods. Constant-voltage charging is the conventional method for lead-acid batteries and is also preferred for VRLA batteries. However, constant current, taper current, and variations thereof can also be used. 

FIGURE 26.12 Constant-voltage charging with current limitation 0.2C of medium-rate pocket plate batteries at 25°C. 

FIGURE 3439 Constant voltage charging of LiAl/MnOj coin-type battery (ML2430 size), with a charging voltage of 3.25 V, at 20 C. From Sanyo Energy Corp.)... 

Many apphcations require batteries to retain capacity on continuous float (constant voltage) charge. In this scenario, the cells are charged whenever their open circuit voltage is less than a predetermined threshold value. The ability of wound C/LiCo02 cells to retain capacity on float charge is indicated in Fig. 35.85, which shows the capacity retained hy ceUs float charged for up to 21 months. Capacity retention was temperature dependent and followed an Arrhenius relationship. The capacity loss rate increased hy a factor of 1.3 for each 10°C rise in temperature. 

Rgure49.2 Mettiodsofcharginglargenickel-cadmium batteries. -, current —, voltage. Charge wHh (a.b) constant current characteristic (c, decreasing current characteristic (e) constant currenl/constant voltage characteristics... 

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