Battery Size Calculator
Calculate battery configuration (series cells) and capacity per cell based on required total capacity and voltage.
Typical: 3.7V (Li-ion), 1.2V (NiMH), 1.5V (Alkaline)
How to Use This Calculator
- Enter the required total capacity in mAh (the total capacity you need).
- Enter the required voltage in volts (the voltage your device needs).
- Enter the cell voltage (3.7V for Li-ion, 1.2V for NiMH, etc.).
- The calculator displays how many cells in series and capacity per cell needed.
Battery Configuration Formula
Battery configuration is calculated from voltage and capacity requirements:
Capacity per Cell = Total Capacity / Cells in Series
Example: Need 5000mAh at 14.8V using 3.7V cells: Cells = 14.8 / 3.7 = 4 cells in series (4S). Capacity per cell = 5000 / 4 = 1250mAh. So you need 4 cells of 1250mAh each connected in series.
Full Description
Battery packs are often made by connecting multiple cells together. Cells can be connected in series (to increase voltage) or parallel (to increase capacity). Understanding battery configuration helps you design battery packs, select appropriate cells, and understand how battery specifications relate to your requirements.
When cells are connected in series, voltages add while capacity stays the same. For example, four 3.7V 2000mAh cells in series create a 14.8V 2000mAh pack. When cells are connected in parallel, capacities add while voltage stays the same. For example, four 3.7V 2000mAh cells in parallel create a 3.7V 8000mAh pack. Many battery packs use combinations of both (series-parallel).
This calculator helps you determine battery configuration for series connections. Enter the required total capacity and voltage, along with cell voltage, and it calculates how many cells in series you need and the capacity per cell. Use it when designing battery packs, selecting cells, or understanding battery specifications. Remember that cells should be matched (same capacity, voltage, and age) for best performance and safety.
Frequently Asked Questions
How do I calculate battery configuration?
Cells in series = Required voltage / Cell voltage. Capacity per cell = Total capacity / Cells in series. For example, to get 14.8V from 3.7V cells with 5000mAh total: 14.8/3.7 = 4 cells in series. Capacity per cell = 5000/4 = 1250mAh.
What does "4S" mean in battery notation?
4S means 4 cells in series. The "S" stands for series. Batteries can also be connected in parallel (P), like 2P for 2 cells in parallel. Series increases voltage, parallel increases capacity. 4S2P means 4 series groups of 2 parallel cells.
How do I choose cell voltage?
Cell voltage depends on chemistry: Li-ion = 3.7V nominal (4.2V max), NiMH = 1.2V, Alkaline = 1.5V, Lead-acid = 2V. Use the nominal voltage for calculations. Li-ion is most common for rechargeable applications.
Can I mix different cell capacities?
In series: All cells must have the same capacity, or the weakest cell limits the pack. In parallel: Cells should have similar capacity and voltage to prevent current imbalance. It's best to use matched cells from the same batch.