Battery runtime

Enter measured output power in W, not the UPS rating in VA. Wh is energy. For identical batteries, series adds voltage and parallel strings add Ah; the Wh mode already describes the entire bank.

Energy estimate: usable Wh ÷ (load W ÷ efficiency + extra idle W). The usable fraction is the energy available from the present charge down to your chosen cutoff. Additional idle power is battery-side consumption; set it to zero if already included in efficiency. Without load or idle draw the model has no discharge, but a real battery still has losses.

Optional Peukert comparison uses the battery’s rated Ah, rated discharge duration H and manufacturer exponent k: Iᵣ = Ah/H; time = H × (Iᵣ/I)^k × usable fraction. At k = 1 it equals the energy estimate. At higher current than Iᵣ, k > 1 reduces time; below Iᵣ it increases it. Use datasheet values within their measured range. The sample k is illustrative.

Both estimates assume constant voltage, load and efficiency. The usable fraction scales Peukert time linearly. Temperature, aging, self-discharge, shutdown voltage and actual UPS runtime curves are not modeled; this does not verify the UPS power rating or predict a specific device’s backup time.