ICS1700A Datasheet, PDF (5/24 Pages) List of Unclassifed Manufacturers – QuickSaver Charge Controller for Nickel-Cadmium and Nickel-Metal Hydride Batteries

ICS1700A
The discharge current pulse amplitude is typically set to about 2.5
times the amplitude of the charging current based on 1.4V/cell. For
example, if the charge current is 4 amps, then the discharge current
is set at about 10 amps. The energy removed during the discharge
pulse is a fixed ratio to the positive charge rate. The amplitude of
the discharge pulse does not affect the operation of the part as
described in this section.
A voltage acquisition window immediately follows a brief rest time
after the discharge pulse. No charge is applied during the rest time
or during the acquisition window to allow the cell chemistry to
settle. Since no current is flowing, the measured cell voltage is not
obscured by any internal or external IR drops or distortions caused
by excess plate surface charge. The ICS1700A makes one
continuous reading of the no-load battery voltage during the entire
acquisition window. The voltage that is measured during this
window contains less noise and is a more accurate representation
of the true state of charge of the battery.
Topping Charge
The third stage is a topping charge that applies current at a rate low
enough to prevent cell heating but high enough to ensure a full
charge.
The topping charge applies a C/10 charging current for two hours.
The current consists of the same pulse technique used during the
fast charge stage; however, the duty cycle of the pulse sequence
has been extended as shown in Figure 5. Extending the time
between charge pulses allows the same charging current used in the
fast charge stage so that no changes to the current source are
necessary. For example, the same charge pulse that occurs every
second at a 2C fast charge rate will occur every 20 seconds for a
topping charge rate of C/10. The CMN indicator flashes at a one
second rate during this stage.
Maintenance Charge
The maintenance charge is intended to offset the natural self-
discharge of NiCd or NiMH batteries by keeping the cells primed
at peak charge. After the topping charge ends, the ICS1700A
begins this charge stage by extending the duty cycle of the applied
current pulses to a C/40 rate. The maintenance charge will last for
as long as the battery voltage is greater than 0.5V at the VIN pin.
The CMN indicator flashes at a one second rate during this stage.
cycle
time
delay time
cycle
time
Figure 5: Representative timing diagram for topping and maintenance charge
5