How long does a battery backup sump pump last?

A battery backup sump pump system typically runs a 1/2 HP pump for 2–7 hours of continuous operation, or 12–24 hours of intermittent cycling, depending on battery capacity and how hard the pump is working.

Runtime is determined almost entirely by the battery you pair with the inverter-charger unit — not the unit itself. A 100Ah AGM battery running a 500W pump delivers roughly 2–2.5 hours of non-stop pumping, but during a real storm where the pump cycles every 10–15 minutes, that same battery can carry you through 12+ hours. The pump's startup surge wattage and duty cycle are the two numbers that matter most when sizing your battery bank.

• Continuous runtime estimate: 2–2.5 hours from a 100Ah AGM battery powering a 500W sump pump.
• Intermittent-cycle runtime: 12–24 hours from a 100Ah battery when the pump runs every 10–15 minutes.
• Runtime formula: Battery Ah × 12V × ~0.85–0.90 efficiency ÷ pump running wattage = approximate hours.
• VIOPUMPO 2500W sump backup system peak rating: 5,000W — handles motor startup surges of 2–3× running wattage.
• Compatible battery types for VIOPUMPO sump systems: AGM and deep-cycle lithium (LiFePO4); standard automotive batteries are not suitable.