Battery Runtime Scenario Calculator

How the battery runtime scenario calculator works

Available DC energy = nominal DC kWh × usable share / 100. Available AC energy = that DC energy × one-way discharge efficiency / 100. Each factor applies once. Manufacturer capacities may already use a usable or AC boundary; do not reapply these factors to such a value without reconciling the basis.

Combined constant AC load is main load plus AC-side auxiliary load. Ideal runtime hours = available AC kWh ÷ combined kW. Zero combined load makes runtime unavailable, rather than displaying an infinite duration. Zero available energy with positive load gives zero modeled runtime.

Energy and power limits are separate. This arithmetic does not certify continuous or surge power, inverter capability, current, wiring, safety or emergency-backup performance. Temperature, aging, voltage-dependent capacity, variable loads and self-discharge are excluded. Tesla’s specification illustrates the distinction between usable energy and output power; none of its product ratings are used as the defaults.

Worked example

10 kWh nominal DC at 80% usable share gives 8 kWh available DC. At 90% one-way discharge efficiency, 7.2 kWh is available on the AC side. A 1.2 kW main load plus 0.1 kW auxiliary load gives about 5.538 hours ideal runtime. Increasing main load to 1.7 kW gives exactly four hours under the same energy assumptions.

Sources and assumptions

The source material explains the underlying calculation or pricing structure. Entered prices, costs, schedules and scenario choices are your assumptions; this tool does not obtain supplier quotes or predict actual results.

• Tesla: separate energy capacity and continuous/peak power specifications
• EIA: power and electrical energy units