1. What is 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 in a UPS system, considering factors like battery voltage, depth of discharge, and system efficiency.

2. How Does the Calculator Work?

The calculator uses the battery capacity formula:

Where:

• Load Power — Total power consumption of connected devices in watts
• Backup Time — Desired runtime in hours during power outage
• Battery Voltage — Nominal voltage of battery bank (typically 12V, 24V, or 48V)
• Depth of Discharge — Fraction of battery capacity that can be safely used (typically 0.5-0.8)
• Efficiency — System efficiency accounting for inverter and other losses (typically 0.85-0.95)

3. Importance of Proper Battery Sizing

Details: Correct battery sizing ensures sufficient backup time while preventing over-sizing (which increases cost) or under-sizing (which reduces backup time and may damage batteries).

4. Using the Calculator

Tips: For accurate results, measure actual load power rather than estimating. Common UPS battery voltages are 12V, 24V, or 48V. Typical depth of discharge is 50-80% for lead-acid batteries (higher for lithium). System efficiency is typically 85-95%.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical depth of discharge for lead-acid batteries?
A: 50-80% is typical for deep-cycle lead-acid batteries. Discharging beyond this can shorten battery life.

Q2: How do I determine my load power?
A: Add up the wattage of all devices to be powered, or use a power meter to measure actual consumption.

Q3: Why is efficiency less than 100%?
A: Efficiency accounts for inverter losses, wiring losses, and other system inefficiencies.

Q4: Can I use this for lithium batteries?
A: Yes, but lithium batteries typically allow deeper discharge (80-100%) and have slightly higher efficiency.

Q5: How do I convert Ah to Wh?
A: Multiply Ah by battery voltage (e.g., 100Ah × 12V = 1200Wh).