Battery wiring
Battery series and parallel calculator
Check a layout you already know, or solve for the smallest whole-battery layout that reaches a target voltage and capacity. The diagram shows topology, not installation detail.
Describe the battery layout
Your planning estimate
Local calculationEnter your values, then calculate. Results will show the formula inputs and rounding used.
Formula used
total V = unit V × series; total Ah = unit Ah × parallel; total Wh = total V × total AhSeries connections add voltage while amp-hours stay the same. Parallel strings add amp-hours while voltage stays the same. Total stored energy equals the resulting voltage multiplied by the resulting amp-hours.
See the full assumptions and rounding policy.
Maintenance and verification
The calculator calls the shared, tested TypeScript calculation modules documented in the methodology. Automated tests cover published examples, invalid inputs, rounding, and result invariants.
SolarMathKit maintains this implementation. The review is an internal technical check, not an independent engineering certification.
Worked example: four 12V 100Ah batteries
Arrange two batteries in each series string and connect two matching strings in parallel.
- Voltage: 12V × 2 in series = 24V.
- Capacity: 100Ah × 2 parallel strings = 200Ah.
- Energy: 24V × 200Ah = 4,800 Wh.
- Battery count: 2 series × 2 parallel = 4 batteries.
Common mistakes to avoid
- Adding amp-hours in a series string.
- Adding voltage across parallel strings.
- Mixing batteries with different voltage, capacity, chemistry, age, or health.
- Using a topology sketch as a cable, fuse, or terminal-layout drawing.
Questions people ask
Does series or parallel create more energy?
No. With the same matching batteries, total Wh is the same. The arrangement changes the voltage and Ah relationship.
Why must target voltage be an exact multiple?
A fixed-voltage battery module can only create whole series steps. The calculator will not invent a fractional battery.
How many parallel strings are safe?
There is no universal number. Current sharing, busbar design, protection, monitoring, and manufacturer limits all matter, so the calculator reports the topology without declaring a construction threshold.