Energy From Cells Calculator

Calculator Inputs

The page stays single-column, while the form uses three columns on large screens, two on medium screens, and one on mobile.

Voltage source mode

Measured cell voltage (V)

Electrons transferred, n

Cathode reduction potential (V)

Anode reduction potential (V)

Reaction quotient Q (optional)

Temperature (K)

Reaction moles per cell

System efficiency (%)

Cells in series

Parallel strings

Internal resistance per cell (Ω)

Load current (A)

Discharge time value

Discharge time unit

Formula Used

Formula	Meaning
E°cell = E°cathode − E°anode	Standard cell potential from reduction potentials.
Ecell = E°cell − (RT / nF) ln(Q)	Nernst equation for non-standard conditions.
Qchem = nFξP	Total chemistry-limited charge, where ξ is reaction moles per cell and P is parallel strings.
Vpack = Ecell × S	Open pack voltage from cells in series.
Rpack = r × S / P	Equivalent internal resistance of the pack.
Vloaded = Vpack − I Rpack	Loaded voltage under constant current.
Energy = V × Q	Electrical energy in joules.
Usable Energy = Energy × η	Adjusts for real-world efficiency losses.
ΔG = −nFE	Gibbs free energy change per mole of reaction.

How to Use This Calculator

Choose direct voltage mode for measured cell voltage, or potential mode for electrode-potential calculations.
Enter electrons transferred and reaction moles per cell. These set the chemistry-limited charge.
Enter series cells, parallel strings, and efficiency to model a full pack instead of one cell.
Add current, time, and internal resistance to estimate loaded voltage, runtime, and delivered energy.
Press the calculate button. The result block appears below the header and above the form.
Use the CSV and PDF buttons to export the latest result summary.

Example Data Table

Mode	Cell V	n	Reaction moles/cell	Series	Parallel	Efficiency	Current	Time	Approx. usable energy
Direct	1.10 V	2	0.50 mol	3	2	90%	1.50 A	2 h	159.20 Wh theoretical usable
Potential	1.25 V	1	0.20 mol	4	1	85%	0.80 A	90 min	22.79 Wh theoretical usable
Direct	3.70 V	1	0.08 mol	2	3	92%	5.00 A	30 min	49.30 Wh theoretical usable

FAQs

1) What does this calculator estimate?

It estimates charge, voltage, energy, power, Gibbs free energy, and runtime for electrochemical cells or battery packs using chemistry data and load conditions.

2) Why do I need the electron count n?

The electron count links the redox reaction to electrical charge through Faraday’s constant. A larger n increases the available charge for the same reaction extent.

3) What is reaction moles per cell?

It is the usable reaction extent inside one cell. The tool multiplies that value by parallel strings to estimate the total pack charge.

4) When should I use potential mode?

Use potential mode when you know cathode and anode reduction potentials, and especially when you also know the reaction quotient for non-standard conditions.

5) Why is loaded voltage lower than open voltage?

Loaded voltage includes the internal resistance drop, modeled as I × R. Higher current or higher resistance lowers the terminal voltage under use.

6) Does usable energy equal delivered energy?

No. Usable energy is the chemistry-based maximum after efficiency losses. Delivered energy also considers the specific current and time you entered.

7) Can I use this for batteries and galvanic cells?

Yes. It works for classroom electrochemical cells, electrolysis planning, and battery pack estimates, as long as the chemistry assumptions are reasonable.

8) Is the runtime exact?

No. Runtime is an estimate at constant current. Real systems also depend on cutoff voltage, temperature, aging, kinetics, and changing internal resistance.