How to use the battery terminal voltage under load calculator
Find how much voltage a battery delivers under load given its internal resistance. Enter open-circuit emf, internal resistance, load current in the fields above; the terminal voltage, power lost inside battery are computed instantly and plotted on the chart so you can see how the answer changes.
Common searches this calculator answers include “battery voltage drop under load”, “internal resistance”, “terminal voltage”, “calculate battery terminal voltage under load”, “find terminal voltage”.
Formula
Variables
- E — Open-circuit EMF (V)
- r — Internal resistance (Ω)
- I — Load current (A)
Worked example
With open-circuit emf = 12 V, internal resistance = 0.2 Ω, load current = 5 A, the calculator gives terminal voltage ≈ 11 V; power lost inside battery ≈ 5 W.
Frequently asked questions
What is the battery terminal voltage under load calculator used for?
Find how much voltage a battery delivers under load given its internal resistance. It helps with questions such as “battery voltage drop under load”, “internal resistance”, “terminal voltage”.
What is the formula for the battery terminal voltage under load calculation?
Terminal voltage (V) = E-I × r. Power lost inside battery (W) = I × I × r. Here E is open-circuit emf (V), r is internal resistance (Ω), I is load current (A).
What inputs do I need for the battery terminal voltage under load calculator?
You need open-circuit emf in V, internal resistance in Ω, load current in A. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use the battery terminal voltage under load calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the battery terminal voltage under load result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.