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Battery Voltage Sag Calculator

Battery Voltage Sag converts the entered electrical measurements into loaded voltage. Use it to the loaded voltage calculation.

Enter values for loaded voltage

Use one consistent electrical operating case for all fields.

V

Enter open-circuit voltage in V.

V

Enter sag at load in V.

How Battery Voltage Sag works

For this case, apply Vload = Voc − sag. Battery Voltage Sag uses Open-circuit voltage, Sag at load to report Loaded voltage.

With the loaded values, loaded voltage evaluates to 12.10 V. Use separate cases for competing input values.

Inputs for Battery Voltage Sag

Open-circuit voltage and Sag at load belong to Battery Voltage Sag. Keep source units with open-circuit voltage. Continue to Battery Charging Power Calculator for charging power.

Defaults make the page immediately testable, but they do not describe a universal installation.

Open-circuit voltage
Example entry: 12.8 V.
Sag at load
Example entry: 0.7 V.

Reading the Battery Voltage Sag result

This output represents Battery Voltage Sag.

Component selection requires more than the arithmetic result; verify margins, transients, and published ratings. Use Battery Round-Trip Efficiency Calculator.

Measurement and units

Battery calculations depend on chemistry, temperature, age, discharge rate, and the limits of the battery management system. Check prefixes on open-circuit voltage.

Alternatives should share one documented measurement convention.

Limits of this calculation

Transient and steady-state sag can differ.

Only variables shown in the equation affect the numerical output. Unentered effects remain outside Battery Voltage Sag.

Questions about Battery Voltage Sag

What does Battery Voltage Sag calculate?

Battery Voltage Sag reports loaded voltage.