Practical guide

How to collect battery-capacity planning inputs

A source-first checklist for target runtime, average load, inverter loss and explicit usable-capacity factors.

Start with a representative measured average load, not an isolated peak or a guessed nameplate sum. Separate direct DC watts from AC appliance watts, and record inverter efficiency at the relevant output plus idle draw. Document the target operating interval and whether it includes a reserve.

Treat usable depth, health and temperature as three distinct explicit factors. Use the exact battery documentation, measured condition and expected operating temperature; do not infer them from chemistry alone. Record the bank voltage only when converting Wh to Ah.

Keep a project note with source URLs, document revisions, measurement instruments, dates, operating states and assumptions. Recalculate when the load profile, battery, inverter, cutoff or environment changes. Capacity arithmetic does not replace current, surge, BMS, wire, fuse, charger or installation checks.