Battery Backup Calculator
Calculate optimal battery capacity and backup duration for your power needs
Appliances & Load
Battery Configuration
Battery Requirements
System Specifications
Cost & Weight
Quick Summary
System Breakdown
How Battery Backup Calculation Works
Load Calculation
Total load is calculated by summing up all appliances: (Wattage × Quantity) for each appliance. Your current total load is 625 watts.
Energy Requirement
Energy needed for backup = Total Load × Backup Hours = 625W × 4h = 2,500Wh
Battery Capacity
Battery capacity in Ah = Energy (Wh) ÷ System Voltage (V) = 3,130Wh ÷ 48V = 65.1Ah
Cost & Weight
Lithium battery cost: 3.13kWh × ₹25,000/kWh = ₹78,125
Pro Tips for Solar Battery Systems
Battery Selection:
- • Lithium: Higher cost, longer life, 80% DoD
- • Lead Acid: Lower cost, shorter life, 50% DoD
- • 48V systems: More efficient for larger loads
- • Consider temperature effects on capacity
System Optimization:
- • Add 20% safety margin to calculations
- • Use energy-efficient appliances
- • Consider peak vs continuous loads
- • Plan for seasonal variations
Current System Summary:
The Battery Backup Calculator helps homeowners and small businesses in India size a battery bank for power backup during outages. Enter your appliances, desired backup duration, battery chemistry and system voltage, and it works out the required capacity in Ah and kWh, the number of batteries, estimated cost and total weight — useful when planning an inverter/UPS battery bank or a solar-plus-storage setup.
Battery Backup Calculator - FAQs
How do you calculate battery capacity for solar backup?
We size batteries in Ah using Capacity (Ah) = Energy needed for backup (Wh) ÷ Depth of Discharge ÷ System Voltage. Energy needed is Total connected load (W) × Backup hours, adjusted for the depth of discharge you select.
What is depth of discharge (DoD) and why does it matter?
DoD is the percentage of a battery's rated capacity that can be safely used. Lithium batteries typically allow 80% DoD, lead-acid only 50%, so lead-acid batteries need roughly 60% more rated capacity to deliver the same usable backup.
Should I choose lithium or lead-acid batteries?
Lithium costs more upfront (around ₹25,000/kWh vs ₹15,000/kWh for lead-acid) but lasts longer, weighs less, and allows deeper discharge, often working out cheaper over the system's lifetime.
Why does system voltage (12V/24V/48V) matter?
Higher voltage systems draw less current for the same power, which reduces cable losses and simplifies the battery bank wiring — 48V is typically recommended for larger backup loads.
Are these battery costs and specifications fixed?
No — battery prices, chemistry options and specifications change frequently. Treat the figures here as indicative estimates and get updated quotes from installers before purchasing.
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