Specifications

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Charge and Discharge
Batteries in Less Time
Using a power supply in constant-
current mode (Figure 1) is a sim-
ple way to recharge batteries, and
it also lets you achieve 100% charge
levels. On the downside, this
method is slow, taking as long as
14-16 hours because the charging
current is only a fraction of the
battery’s amp/hour rating.
Pulse charging, also called tran-
sient mode, shortens the charging
time, yet still charges the battery to
over 90% capacity (Figure 2). The
electronic load acts as a switch,
providing the current pulses. (Note
that you can also use an electronic
load to program constant-current
charging.) Figure 3 shows a typical
pulse-charging current waveform.
To simulate battery drain, you can
also program the electronic load to
discharge batteries with either con-
stant or pulse current waveforms.
In some cases, pulse discharging
does a better job of mimicking a
product’s energy-saving features.
Simulating cellular phone battery
discharge, for instance, is complex
due to the phone’s various operating
modes—standby, dialing, and talk-
ing. You can create the necessary
tri-level discharge current wave-
form shown in Figure 4 using the
electronic load.
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Power
Supply
Battery
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Power
Supply
Electronic
Load
Battery
Figure 1: Constant current charging is simple
and effective, but it can be very slow. (The diode
prevents the battery from discharging through the
power supply if the supply voltage drops below the
battery voltage.)
Figure 2: Pulse charging using an electronic load
is much faster, while still achieving 90% recharge.
Figure 4: A complex waveform that simulates
the energy-saving features in portable, battery-
powered products.
Figure 3: A typical pulse charging waveform cre-
ated with an electronic load.
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