4

ICS1700A

Figure 3: Cycle-to-cycle increase of the soft-start current pulse widths

Fast Charge

In the second stage, the ICS1700A applies the charging current in

a series of charge and discharge pulses. The technique consists of a

positive current charging pulse followed by a high current, short

duration discharge pulse. The cycle, shown with charge, discharge,

rest and data acquisition periods in Figure 4, repeats every second

until the batteries are fully charged.

The amplitude of the current pulse is determined by system

parameters such as the current capability of the charging system,

the desired charge rate, the cell capacity and the ability of that cell

to accept the charge current. The ICS1700A can be set for four

user-selectable fast charge rates from 15 minutes (4C) to two hours

(C/2). Charge pulses occur approximately every second. The CMN

indicator is activated continuously during this stage.

Figure 4: Charge cycle showing charge and discharge current pulses

Initial Pulse

Width

cycle time

cycle time

cycle time

Initial Pulse

Width

Initial Pulse

Width

increment

time

2 x increment

time

fast charge pulse width

acquisition time

rest

time

rest

time

discharge pulse width

voltage

cycle time