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BenchSupply / Battery runtime

Battery planning

Estimate runtime before you build it into an enclosure.

Start with nominal battery energy, then deliberately discount it for converter losses, cutoff voltage and real operating conditions.

Use average load rather than a peak figure. For lithium packs, a BMS may cut off before nameplate energy is available; for lead acid, useful capacity depends strongly on discharge rate.

Method

Watt-hours make unlike batteries comparable.

Nominal watt-hours equal volts multiplied by amp-hours. Divide usable watt-hours by average load watts for a first runtime estimate. The allowance field is not a hidden correction: make it lower when you need conservative planning.