Battery Runtime Calculator
DC battery runtime from capacity (Ah) and load. Constant load, no Peukert.
Runtime
8.00 h
Usable capacity
80.0 Ah
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These calculators are engineering design aids intended for estimation and educational purposes. They do not replace professional engineering judgment or compliance with applicable standards (ABYC, NEC, IEC, SAE, or local regulations). Always verify final designs against relevant codes and manufacturer specifications.
What this tool calculates
Estimated runtime based on battery capacity (Ah), load current (A), and depth of discharge. Basic formula: Runtime (hours) = Capacity (Ah) / Load (A).
For wiring the battery to loads, use voltage drop and wire sizing.
Real-world considerations
Actual runtime depends on battery chemistry (lead-acid vs lithium), Peukert effect (for lead-acid at high discharge rates), temperature, and age. For lead-acid systems, 50% depth of discharge is commonly recommended to preserve battery life. Lithium systems often support 80–100% usable capacity.
Marine example
100Ah AGM battery, load 10A, usable capacity at 50% DoD = 50Ah. Estimated runtime: 50Ah / 10A = 5 hours.
Compliance & engineering note
This tool assumes steady current draw and does not model inverter inefficiency, surge loads, battery aging, or temperature derating. Always verify critical system endurance with conservative assumptions.
FAQ
Related tools
Save this to a LoomLab project for full harness validation.