Correct battery charging is very important to assure the maximum possible working life for LCB battery.
There are four major method of charging.
 Constant Voltage Charging
 Constant Current Charging
 Two Stage Constant Voltages Charging
 Taper Current Charging


Constant Voltage Charging
Constant voltage charging is recommended method of charging sealed lead acid batteries. When using this type of charger, it is necessary to closely control the actual voltage to the limit advised. It is suggested that the initial current to be set at 0.2C Amps.
The attached graph indicates the time taken to fully recharge the battery. It should be noted that the graph illustrated is for a fully discharged battery i.e.: a battery that has reached the minimum cell voltage recommended for its discharge time. It is also seen that it is necessary to replace a greater amount of energy into the battery when it is on charge than was taken out of the battery on discharge. The actual current indicating that the battery is fully charged is shown in the individual specifications.


BATTERY CHARGING CHARACTERISTICS (Floating Use)


BATTERY CHARGING CHARACTERISTICS (cycle Use)


Notes: It is necessary to ensure that the voltage is correctly set. A voltage set too high will result in grid corrosion, gassing and consumption of the water in the electrolyte which causing premature battery failure. A voltage set too low will lead to sulphation of the plates causing loss of capacity and ultimately shortening the life of the battery.


Constant Current Charging
This method of charging is generally not recommended for valve-regulated batteries. It is necessary to understand that if the batteries are not removed from the charger as soon as possible after reaching a state of full charge. But it is a effective method for charging a number of series connected batteries at the same time. Considerable damage will occur to the batteries due to overcharging. Following figure showed the characteristics of battery under continuous overcharge conditions.

Two — Step Combination Charging
This system employs two steps of charging, it can be constant current-constant voltage, constant current constant current, etc. Yet it should not be used where the battery and load are connected in parallel.

At the initial charging stage, the current flowing into the battery is limited to a value of 0.3C Amps. The charging voltage across the battery terminals rises, during the charging process, to a value to the constant voltage output of the charger, which is set to 2.45V/cell. In stage A to B at 2.45V/cell, the current will decrease to switching point, where the value of this decreasing current is sensed causing the circuit to switch into the second stage C, the voltage will down to 2.3V/cell. This time battery has recovered about 80% of its rated capacity. This is one of the most efficient charging methods available as the recharge time minimized during the initial stage whilst the battery is protected from overcharge by the system switching to stage 2 charge at the switching point.


Taper Current Charging
In this system, a charging cut-off circuit should be incorporated in the charger to prevent overcharge. It can be utilized for some industrial uses and trickle charging system.


Effect of Temperature on Charging Voltage
Within the normal operating parameters of 20°C-30°C voltage compensation for operating temperature may not be necessary. However, to maximize the life of the battery, temperature compensation for operating temperatures outsides this temperatures range should be considered. The attached graph shows the correct voltages for LCB batteries in float service at 25°C and cycle service at 25°C. It should be noted that the voltage is decreased with a rise in temperature and increased with a fall in temperature.