Battery Series-Parallel Calculator
Voltage and capacity for series and parallel cells.
Runs in your browser. Nothing is uploaded — your input is processed on this device and discarded when you close the tab.
Battery Series-Parallel Calculator
How to use this tool
- Enter your values in the fields above.
- Press Generate. The result appears below the buttons.
- Use Load sample to see a worked example, or Clear to start again.
Worked example
For 3.7 V, 2.5 Ah cells with 4 in series and 2 strings in parallel: voltage is 3.7 x 4 = 14.80 V, capacity is 2.5 x 2 = 5.00 Ah, energy is 14.80 x 5.00 = 74.00 Wh, using 8 cells.
What this tool does not do / Limits
Series adds voltage while capacity stays the same; parallel adds capacity while voltage stays the same. This assumes identical cells; mixing cell types, ages or charge levels in a real pack is unsafe and needs proper battery management.
Frequently asked questions
Why does series not add capacity?
The same current flows through every series cell, so the string runs out when one cell's capacity is used up.
Do I need a battery management system?
For lithium packs, yes in practice: a proper management system is needed for safe charging, balancing and protection, and this calculator does not replace it.
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