How it Works
1. Calculate Total Load (Watts). 2. Set Duration (Hours). 3. Apply DoD Factor (e.g. 50% for Lead Acid, 80-90% for Lithium).
Formula: $Capacity_{Wh} = \frac{Load_{W} \times Time_{h}}{DoD}$.
What is Backup Battery Sizer Calculator?
Determines the total Watt-Hours (Wh) needed to run specific appliances for a set duration, accounting for battery chemistry constraints like Depth of Discharge (DoD).
Step-by-Step Guide
- Total Load – Sum wattage of all devices running simultaneously.
- Run Time – Hours of backup needed.
- Battery Type – Select chemistry (affects usable capacity).
- Result – Required Wh/Ah.
Example
Input: 500W Load, 4 Hours, Lithium
Result: 2,222 Wh Required
FAQ
What is DoD?
Depth of Discharge. How much energy you can safely use. Lead Acid ~50%, Lithium ~90%.
Wh to Ah?
Ah = Wh / Battery Voltage (e.g. 12V or 24V).
Inverter efficiency?
Inverters lose ~10-15% energy; calculate this overhead.
Starting watts?
Motors (fridges/pumps) need 3x surge power to start.
Lifespan?
Lithium lasts 10+ years; Lead Acid 3-5 years.
Conclusion
Proper sizing prevents blackout failures. Remember that you cannot use 100% of a battery's rated capacity without damaging it. Always oversize your bank by 20% for safety.