Battery Series vs Parallel Calculator
Wiring batteries in series changes your voltage. Wiring them in parallel changes your capacity. Mix them up and you can damage your batteries or your inverter. Enter your battery specs and how many you’re wiring together below to see the exact result before you connect anything.
Series vs Parallel Calculator
See the resulting voltage and capacity for your battery bank.
Wired + to – to increase voltage
Wired + to +, – to – to increase capacity
The Formula
Series wiring: Total Voltage = Single Battery Voltage × Number in Series (capacity stays the same)
Parallel wiring: Total Capacity (Ah) = Single Battery Capacity × Number in Parallel (voltage stays the same)
Series vs Parallel: What's the Difference
Series means connecting the positive terminal of one battery to the negative terminal of the next. This adds each battery's voltage together while the Ah capacity stays the same as a single battery. Two 12V 150Ah batteries in series give you 24V at 150Ah, this is how you build a 24V or 48V system from 12V batteries.
Parallel means connecting positive to positive and negative to negative across batteries. This keeps the voltage the same but adds the Ah capacities together. Two 12V 150Ah batteries in parallel give you 12V at 300Ah, more backup time at the same voltage.
Many home solar and UPS setups combine both: for example, four 12V 150Ah batteries wired as two series pairs, then those pairs wired in parallel, gives you 24V at 300Ah. Always use identical batteries (same brand, age, and capacity) when wiring a bank, mismatched batteries wear unevenly and can damage the whole bank over time.
Common Battery Bank Configurations
| Setup | Config | Result (12V 150Ah batteries) |
|---|---|---|
| Single battery | 1S1P | 12V, 150Ah |
| Two in parallel | 1S2P | 12V, 300Ah |
| Two in series | 2S1P | 24V, 150Ah |
| Four batteries (2 series pairs, parallel) | 2S2P | 24V, 300Ah |
Once you know your bank's total capacity, use our Battery Backup Time Calculator to find out how long it will actually run your appliances.
Frequently Asked Questions
Can I mix different battery brands in series or parallel?
It's not recommended. Different brands, ages, or capacities charge and discharge at slightly different rates, which causes uneven wear and can shorten the life of the entire bank. Always use identical batteries when wiring a bank together.
Does wiring batteries in parallel double the voltage?
No. Parallel wiring keeps voltage the same and adds capacity (Ah) together. To increase voltage, you need series wiring instead, which adds voltage while keeping capacity the same as one battery.