Battery series and parallel calculator
Pack voltage, capacity and energy from the wiring arrangement.
Fill in the fields and the result will appear here automatically.
Compare the nominal voltage, capacity and energy of an ideal pack of identical cells. S is the number in series per branch; P is the number of identical parallel branches. Swapping S and P changes voltage and Ah but preserves nominal Wh when the number of cells stays the same. These values alone do not establish device compatibility or permissible current.
How it works
Formula and logic
A series branch has U = S·Ucell and retains one cell's Ah. P identical branches give C = P·Ccell. Energy E = U·C = N·Ucell·Ccell Wh. The model assumes identical cells and excludes imbalance, wiring and losses.
Example
Twelve 3.7 V, 3.4 Ah cells in 4S3P give 14.8 V, 10.2 Ah and 150.96 Wh. In 3S4P they give 11.1 V, 13.6 Ah and the same 150.96 Wh. A 4S4P layout needs 16 cells and is rejected when N = 12.
Fields and units
- Total cells — 1
- Cell voltage — V
- Cell capacity — Ah
- Cells in series — 1
- Strings in parallel — 1
How to use
- — Enter the cell count and integer S and P from 1 to 500.
- — Check N = S·P; surplus cells are neither rounded nor discarded.
- — Enter the nominal voltage and capacity of one identical cell.
- — Check the full operating voltage range, current and BMS requirements against the system specifications, not only the nominal voltage.
Method and limitations
- Calculation method
- Formula and logic
- Data or methodology source
- Victron: series and parallel batteries and current sharing Victron Lithium Battery Smart: system and BMS requirements — for the specified battery family
- Limitation
- Nominal identical-cell model. Protection, balancing, current limits and compatibility require the actual equipment specifications.
FAQ
What adds when cells are connected?
Series voltages add; capacities in Ah add for identical parallel branches. These formulas describe identical cells in a rectangular S×P arrangement.
Will a nominal 14.8 V pack suit a 12 V device?
Nominal voltage is insufficient. Check charged and discharged voltage ranges, device and cell current limits, protection and BMS requirements. The calculation does not establish compatibility.
Does a parallel connection change only run time?
It increases Ah in the ideal model. Real current capability also depends on cells, connections, current sharing and protection, none of which is calculated here.
Can I enter different cells or fractional counts?
No. Cells are assumed to have identical ratings, and counts must be integers. With dissimilar cells, these products do not describe the weakest-cell limit or balancing.