Cell Pack Designer

Cell Pack Designer helps you plan DIY battery packs built from 18650, 21700, or LiFePO4 cells, before you spend money on parts.

Pick a cell preset (or enter your own specs) and a series x parallel configuration, and instantly see:

- Pack nominal and full-charge voltage
- Total capacity in Ah and Wh
- Continuous and peak discharge current
- Estimated pack weight
- Estimated build cost (cells, BMS, strip, wiring)
- Recommended BMS current rating, with a warning if your BMS is undersized
- Interconnect strip sizing: nickel strip thickness, width and layers, or a clear "switch to copper" verdict
- Main lead wire gauge (AWG and mm2) with a voltage-drop check for your lead length, plus balance lead guidance
- Estimated voltage sag under load

Cell specs, BMS rating and margin, prices, weight overhead and lead length are all editable, so the numbers match the exact cells and parts you are actually using.

Save multiple pack designs and compare them side by side to find the configuration that fits your project, whether that is an e-bike, a solar storage bank, a power tool pack, or a robotics project.

Cell Pack Designer works completely offline. Nothing you enter ever leaves your device.

This app is a planning and estimation tool. Always follow proper safety practices, use a real BMS, and verify specs against your actual cell datasheets and your strip and wire suppliers' ratings before building a physical pack. Lithium battery packs can be dangerous if built incorrectly.