Inverter Battery Backup Time Calculator
Enter your battery capacity (150Ah, 200Ah, 220Ah), system voltage (12V / 24V), and wattage load to get accurate real-world backup hours accounting for inverter efficiency and depth of discharge.
Continuous backup for a 350W load on 12V 150Ah battery.
Battery Capacity & Voltage
12V · 150 AhRunning Load in Watts
350 WattsHow This Calculation Works & Technical Formula
How to use this tool:
- Choose your battery Ah (Ampere-Hour) capacity (e.g., 100Ah, 150Ah, 200Ah, 220Ah).
- Select single battery (12V) or dual battery (24V) inverter system.
- Specify total running wattage or use our quick appliance toggles.
- Get exact real-world backup duration in hours and minutes.
Frequently Asked Questions
How long will a 150Ah battery last on a 300W load?+
On a 12V 150Ah battery (1800Wh nominal capacity) with 80% inverter efficiency and 80% safe depth of discharge (DoD), usable energy is ~1,152 Wh. Dividing by 300W load yields approximately 3.8 to 4.0 hours of continuous backup.
What is Depth of Discharge (DoD) in lead-acid vs lithium batteries?+
Standard tubular lead-acid batteries should only be discharged to 75-80% to preserve plate longevity. Lithium iron phosphate (LiFePO4) batteries can safely discharge up to 90-95% without damaging capacity.
Other Power Backup Calculators You Might Need
View All 10 Tools →Inverter Size Calculator
Find the exact Inverter VA rating required for your home appliances
Battery Charging Time
Know charging hours & electricity bill units consumed per full charge
Solar Rooftop Calculator
Estimate Solar kW capacity, number of panels, and required roof area