Datasheet

Section 6: Rechargeable battery measurements Model 2461 Interactive SourceMeter® Instrument User's Manual
6-2 2461-900-01 Rev. A / November 2015
For both the charging and discharging cycles, you configure the Model 2461 to source voltage and measure
current. The following figures show simplified schematics for the charge and discharge cycles.
Figure 26: Model 2461 charge-discharge cycle
1
Model 2461 is in source mode (V
S
> V
B
). Instrument functions as a
power supply; charge current (i) is positive.
2
Model 2461 is in sink mode (Vs < V
B
). Instrument functions as an
electronic load; discharge current (i) is negative.
Charging
A battery is usually charged using a constant current. To do this, use a Model 2461 as a voltage
source set to the voltage rating of the battery, with the target charging current set as the current limit.
At the start of the test, the battery voltage is less than the voltage output setting of the Model 2461.
As a result, this voltage difference drives a current that is immediately limited to the user-defined
current limit. When in current limit, the Model 2461 acts as a constant current source until it reaches
the programmed voltage level. As the battery becomes fully charged, the current decreases until it
reaches zero or near zero. To prevent safety hazards or damage to the battery, be careful not to
overcharge the battery.
Discharging
When discharging a battery, the Model 2461 operates as a sink because it is dissipating power
instead of sourcing it. The voltage source of the Model 2461 is set to a lower level than the battery
voltage. The current limit sets the discharge rate. When the output is enabled, the current from the
battery flows into the HI terminal of the Model 2461. As a result, the current readings are negative.
The discharge current should stay constant until the battery voltage decreases to the voltage source
setting of the Model 2461.