ICS1712M GALAXY [Galaxy Power, Inc.], ICS1712M Datasheet - Page 6

• Manufacturer Part Number: ICS1712M
• Description: Charge Controller for Nickel-Cadmium and Nickel-Metal Hydride Batteries
• Manufacturer: GALAXY [Galaxy Power, Inc.]

ICS1712
Charge Termination Methods
Several charge termination schemes, including voltage slope,
temperature slope, maximum temperature and two overall charge
timers are available. The voltage slope and negative voltage slope
methods may be used with or without the temperature slope and the
maximum temperature method. Maximum temperature and the fast
charge timer are available as backup methods.
Voltage Slope Termination
The most distinctive point on the voltage curve of a charging
battery in response to a constant current is the voltage peak that
occurs as the cell approaches full charge. By mathematically
calculating the first derivative of the voltage, a second curve can be
generated showing the change in voltage with respect to time as
shown in Figure 6. The slope will reach a maximum just before the
actual peak in the cell voltage. Using the voltage slope data, the
ICS1712 calculates the point of full charge and accurately
terminates the applied current as the battery reaches that point. The
actual termination point depends on the charging characteristics of
the particular battery.
Figure 6: Voltage and slope curves showing inflection and zero slope points
6
Cells that are not thoroughly conditioned or possess an unusual cell
construction may not have a normal voltage profile. The ICS1712
uses an alternate method of charge termination based on a slight
decrease in the voltage slope to stop charge to cells whose voltage
profile is very shallow. This method looks for a flattening of the
voltage slope which may indicate a shallow peak in the voltage
profile. The zero slope point occurs slightly beyond the peak
voltage and is shown on the voltage curve graph.