Electricity calculator group

Batteries Calculators

Plan battery energy, charging, discharge, heat, efficiency, and pack configuration.

Define the battery condition before calculating

Battery voltage and capacity change with chemistry, temperature, age, state of charge, and discharge rate. Record those conditions with every result.

Nameplate amp-hours, usable amp-hours, stored watt-hours, and deliverable energy are not interchangeable. Choose the calculator whose output matches the planning question.

Batteries calculators by result

Amp-Hour Watt-HourCalculate stored energy from battery capacity and nominal voltage.Battery Series ParallelCalculate pack voltage, capacity, and energy from cell ratings and configuration.Battery Bank CapacityCalculate bank capacity from daily load and bank voltage.Peukert Battery RuntimeEstimate lead-acid runtime using capacity, rated discharge time, load current, and Peukert exponent.Battery C-RateCalculate discharge C-rate from current and capacity.Battery Charging TimeEstimate charging time from capacity, average current, and charge efficiency.Depth of DischargeCalculate depth of discharge from capacity removed and rated capacity.Battery State of ChargeCalculate state of charge from remaining capacity and usable full capacity.Battery Energy DensityCalculate volumetric energy density from stored energy and battery volume.Battery Specific PowerCalculate specific power from peak power and battery mass.Battery Internal ResistanceCalculate battery internal resistance from a documented load test.Battery Voltage SagCalculate loaded voltage from open-circuit voltage and sag at load.Battery Heat GenerationCalculate battery heat from current and internal resistance.Battery Round-Trip EfficiencyCalculate round-trip efficiency from discharged energy and charging energy.Battery Self-DischargeCalculate capacity remaining from initial capacity and monthly loss.Battery Cycle LifeCalculate estimated service years from rated cycles and cycles per year.Battery Capacity FadeCalculate remaining capacity from initial capacity and capacity fade.Cell Balancing ResistorCalculate balancing resistor from cell voltage and bleed current.Battery Pack Stored EnergyCalculate pack energy from pack voltage and pack capacity.Battery Charging PowerCalculate charging power from charging voltage and charging current.

Pack configuration and stored energy

Series cells increase voltage; parallel strings increase capacity and current capability. The series-parallel page therefore asks for cell voltage and cell capacity instead of hiding a fixed cell type.

Pack energy is an ideal nominal value. BMS limits, cell matching, bus resistance, enclosure temperature, and allowable current determine whether that energy is usable.

Runtime, charging, and voltage behavior

Runtime estimates should use a discharge model appropriate to the chemistry. The Peukert page includes rated discharge time and an adjustable exponent because one universal exponent is not defensible.

Charging time depends on average current and charge efficiency, then may be extended by tapering, balancing, and temperature control. Voltage sag and heat require internal resistance measured at a documented load.

Life and efficiency comparisons

Cycle life, self-discharge, capacity fade, and round-trip efficiency should be compared at matching temperature and depth of discharge. Manufacturer test conditions often differ from field duty.

Use separate new, aged, warm, and cold cases when those states could control the design.