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Enter your assumptions above and calculate locally in this browser. No data is uploaded.
How this calculator works
Usable Wh = nominal volts × Ah × usable capacity × assumed efficiency; runtime = usable Wh / load watts.
Important: Real vehicle lead-acid batteries lose usable energy at higher discharge, aging and temperature. This does not test CCA or starting reliability.
Illustrative inputs only. This is not official vehicle safety, valuation or legal advice.