Battery building tools
24 free calculators, grouped by the question you're trying to answer. Nothing here needs an account, and nothing you type leaves your browser.
New to this? Start with the Pack Planner →
Design
What am I building?E-bike Range & Battery CalculatorEstimate riding distance or the battery energy your trip needs.Open tool →Pack PlannerUse this when you know the device, not the pack.Open tool →3D Pack DesignerUse this when you need real dimensions and a layout.Open tool →STL GeneratorUse this when you want printable holders and enclosures.Open tool →Powerwall PlannerUse this when the pack is part of a whole power system.Open tool →
Validate
Will it hold up?Solar Charge Time CalculatorEstimate how many days your panels need to recharge a battery.Open tool →Pack Design ValidatorUse this before you weld — pass, warning, or fail.Open tool →Battery Runtime & Backup SizingEstimate runtime or find the battery capacity your loads need.Open tool →Battery Charge Time CalculatorEstimate recharge time, including the slowdown near full charge.Open tool →Thermal & Layout VisualizerUse this to find hotspots and spacing problems.Open tool →Cell Resistance EstimatorUse this to test cells before trusting them.Open tool →Safety Checklist GeneratorUse this as the last step before you power on.Open tool →
Size
What parts do I need?Pack BuilderUse this to balance the cells you already own.Open tool →BMS PickerUse this to match a BMS to your cell count and current.Open tool →DC Wire Size & Voltage DropFind a wire size for your drop target, or check an existing cable.Open tool →Car Audio CalculatorUse this when you are going lithium for car audio.Open tool →Cost vs Performance OptimizerUse this to compare cost per kWh across cells.Open tool →
Reference
Where do I look it up?Watts to Amps CalculatorFind current from power and voltage, for DC or AC circuits.Open tool →Ohm’s Law CalculatorSolve voltage, current, resistance and power from two known values.Open tool →LiFePO4 Voltage ChartCompare LiFePO4 discharge curves and voltage settings for cells and battery banks.Open tool →AWG to mm² & mm ConverterLook up conductor area and diameter, then check a wire in your circuit.Open tool →Battery Capacity & Energy ConverterConvert mAh, Ah, Wh, and kWh, or compare battery labels.Open tool →Cell DatabaseSpecs and tested ratings for hundreds of cells.Open tool →Essential Tools & SuppliesThe gear we actually use, one honest pick per category.Open tool →
Partner
Essential tools & suppliesSpot welders, testers, nickel strip, safety gear — one honest pick per category. We earn a commission.
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