Work out battery life instantly with clear inputs, formula shown and shareable results.
Runtime is usable capacity divided by average current. The efficiency term covers Peukert losses, converter inefficiency and the fact that rated capacity is measured at a gentle discharge rate — draw a battery hard and it delivers noticeably less than its label.
Battery runtime
hours = capacity (mAh) x efficiency / average current (mA); C rate = current / capacity
Electrical results are planning estimates only. Verify against the applicable wiring rules (IEC 60364, BS 7671, NEC or local code) and have all installation work designed and checked by a qualified electrician.
Discharge current expressed as a multiple of capacity. A 2,600 mAh cell at 2.6 A is 1C. Above about 1C most chemistries lose usable capacity.
Because energy, not peak power, sets runtime. Compute a duty-cycle-weighted average of active and sleep currents.