Free Battery Pack Series-Parallel Calculator

Welcome to our Battery Pack Series‑Parallel Calculator, your go‑to tool for designing custom battery packs with precision and ease. Whether you’re planning a DIY battery build, assembling power packs for robotics, electric vehicles, or energy‑storage systems, this calculator simplifies the process of determining the correct number of cells required in both series and parallel configurations.

Why use this calculator?

Designing a battery pack requires careful calculation of two key parameters: voltage (via series connection) and capacity (via parallel connection). Mis‑calculations can lead to inefficient systems, unbalanced packs, or unsafe operation. Our tool removes the guesswork: you input your target voltage and capacity, select or input the cell specification, and instantly get the series‑parallel count.

How it works

1. Select a cell model from the dropdown – for example, Samsung INR18650‑25R (3.6 V, 2500 mAh), Sony US18650VTC6 (3.6 V, 3000 mAh), LG INR18650MJ1 (3.6 V, 3500 mAh), Panasonic NCR18650B (3.6 V, 3400 mAh), Samsung INR21700‑40T (3.6 V, 4000 mAh), Molicel P42A (3.6 V, 4200 mAh) or standard/high‑capacity LiPo (3.7 V, 2200/5000 mAh).
2. Alternatively, choose Custom Input to enter your own cell voltage (V) and capacity (mAh).
3. Enter your Target Voltage (V) and Target Capacity (mAh) for the pack you intend to build.
4. Click Calculate – the tool will compute how many cells you need in series, how many in parallel, and thereby the total cell count.
5. Optionally click Export as PNG to download a snapshot of your configuration for documentation, sharing or future reference.

Who this is for

• Makers, hobbyists and engineers designing custom packs for drones, RC vehicles, e‑bikes or energy storage.
• Product designers and prototypers needing quick pack‑spec calculations without spreadsheets.
• Students and educators working on battery‐design projects who need clear, visual support.
• Anyone building safely and avoiding guesswork when grouping Li‑ion or Li‑Po cells into series/parallel arrays.

Key features at a glance

• Pre‑loaded with popular 18650/21700 cells and LiPo options.
• Custom input supports unique or proprietary cells.
• Calculates both voltage (series count) and capacity (parallel count).
• Exportable PNG snapshot for record‑keeping or collaboration.
• Clean, user‑friendly interface with no installed software required.

Important notes / Safety reminders

• Ensure that all cells used are of the same model, age, capacity and internal resistance when assembling packs.
• When paralleling cells, ensure good balancing and consistent state‑of‑charge to avoid internal current flows.
• Series‑connections must be matched and secured to prevent failure or imbalance.
• This tool provides counts based on ideal assumptions; always follow manufacturer datasheets and safe‑assembly practices for final pack builds.
• If you’re unsure about handling Li‑ion or Li‑Po cells, seek expert advice — battery packs can be hazardous if built incorrectly.

Frequently Asked Questions (FAQ):

Q1: What is “series” vs. “parallel” in a battery pack?
A: In a series connection, cells are connected end‐to‐end (positive to negative) to increase voltage while capacity (mAh) remains the same. In a parallel connection, cells are connected positive to positive, negative to negative, to increase capacity while voltage remains unchanged. The calculator uses both to meet your target voltage and capacity.

Q2: If I input a target voltage of 36 V and capacity 10,000 mAh using 3.6 V/3000 mAh cells, what happens?
A: The tool will compute the number of cells you need in series (to reach ~36 V) and in parallel (to reach ~10,000 mAh) based on your selected cell specs. Example: 36 V ÷ 3.6 V ≈ 10 cells in series; then to get ~10,000 mAh using 3000 mAh cells you’d need ~4 in parallel (4×3000 =12,000 mAh). Total cells = 10 × 4 = 40 cells.

Q3: Can I use the calculator for custom cells not listed in the dropdown?
A: Yes — choose the “Custom Input” option to enter your cell’s nominal voltage and capacity manually. The calculator will treat those values in the same way as predefined models.

Q4: What does the “Export as PNG” button do?
A: Clicking “Export as PNG” generates an image file of your calculation results, including series count, parallel count and total cell count. It’s useful for documentation, sharing or archiving your design for review or collaboration.

Q5: Does this tool guarantee safe operation of the battery pack?
A: No — the calculator helps with cell‐count calculations only. Safe pack design also depends on cell quality, matching cells, proper balancing, thermal management, correct wiring and protection circuits (BMS). Always follow best practices, manufacturer guidelines and safety standards.

Q6: Why do the cell voltage values (e.g., 3.6 V or 3.7 V) matter?
A: Nominal voltage per cell defines how many cells in series are needed to reach your target pack voltage. For example, dividing your target pack voltage by the cell’s nominal voltage gives the number of cells in series. Accurate voltage values ensure your pack meets system requirements.

Q7: What if I select a high‑capacity LiPo cell (e.g., 5000 mAh) — does that change anything?
A: Yes — a cell with more capacity means you need fewer cells in parallel to hit the target capacity (though series count remains determined by voltage). For example, fewer 5000 mAh cells might be required than 2200 mAh ones to reach the same pack capacity, which can reduce complexity, weight and cost.