1. What is the Battery Capacity Calculation?

The battery capacity calculation determines the required ampere-hour (Ah) rating of a battery needed to power a specific load for a desired backup time, accounting for battery voltage, depth of discharge, and system efficiency.

2. How Does the Calculator Work?

The calculator uses the battery capacity formula:

Where:

• Load Power — The power consumption of your equipment in watts
• Backup Time — Desired runtime in hours during power outage
• Battery Voltage — Nominal voltage of your battery system (typically 12V, 24V, or 48V)
• Depth of Discharge — Maximum recommended discharge level (typically 0.5-0.8)
• Efficiency — System efficiency including inverter losses (typically 0.85-0.95)

Explanation: The formula converts your power requirements into battery capacity while accounting for real-world inefficiencies and battery limitations.

3. Importance of Battery Sizing

Details: Proper battery sizing ensures your backup system meets runtime requirements while maximizing battery life by not exceeding recommended discharge levels.

4. Using the Calculator

Tips: Enter all values as positive numbers. Typical values: Depth of Discharge (0.8 for lead-acid, 0.9 for lithium), Efficiency (0.9 for systems with inverter).

5. Frequently Asked Questions (FAQ)

Q1: What's a typical depth of discharge for lead-acid batteries?
A: 50-80% for flooded lead-acid, 50-70% for AGM batteries to maximize lifespan.

Q2: How does temperature affect battery capacity?
A: Capacity decreases in cold temperatures - may need 10-20% extra capacity in cold climates.

Q3: Should I add a safety margin?
A: Yes, consider adding 10-20% extra capacity to account for battery aging and unexpected loads.

Q4: What's the difference between Ah and Wh?
A: Ah (ampere-hours) is capacity at a specific voltage, Wh (watt-hours) is total energy (Ah × V).

Q5: Can I use this for lithium batteries?
A: Yes, but lithium batteries typically allow deeper discharge (80-90%) and have higher efficiency.