Section 5: Source-measure considerations
2470 High Voltage SourceMeter Instrument Reference Manual
5-18
2470-901-01 Rev. A /
May
2019
Battery charge and discharge
To prevent personal injury or damage to the 2470, do not attempt to charge nonrechargeable
batteries. Some of the batteries that can be charged with a 2470 are nickel cadmium (Ni-Cd),
nickel metal hydride (Ni-MH), lithium ion (Li-ion), rechargeable alkaline, and lead acid. If you
are working with a battery type that is not listed here, please contact your local Keithley
office, sales partner, or distributor, or call one of our Applications Engineers to get technical
assistance.
Always follow the battery manufacturer's requirements for charging or discharging batteries
using a 2470. Failure to properly charge or discharge batteries may cause them to leak or
explode, resulting in personal injury and property damage. Overvoltage and current
protection should be provided in the charge circuit, external to the instrument, when charging
batteries without built-in protection.
Do not charge or discharge batteries that exceed 1100 V at 10.5 mA, 210 V at 105 mA, or 21 V
at 1.05 A.
Charging
A battery is usually charged using a constant current. To do this, use a 2470 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 2470. As a result, this
voltage difference drives a current that is immediately limited to the user-defined current limit. When
in current limit, the 2470 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 2470 operates as a sink because it is dissipating power instead of
sourcing it. The voltage source of the 2470 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 2470. 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 2470.