1. What is the LiFePO4 Battery Size Calculator?

This calculator determines the required capacity (in ampere-hours) of a LiFePO4 battery bank for a UPS system based on the load power, desired runtime, and battery voltage.

2. How Does the Calculator Work?

The calculator uses the following formula:

Where:

• UPS Load VA — The volt-amp rating of your UPS load
• Time — Desired runtime in hours
• LiFePO4 Voltage — Nominal voltage of your battery bank (typically 12.8V, 25.6V, or 51.2V)

Explanation: The formula converts the energy requirement (VA × hours) to battery capacity (Ah) based on the battery bank voltage.

3. Importance of Proper Battery Sizing

Details: Correct battery sizing ensures your UPS can support the connected load for the required duration while maintaining battery health and longevity.

4. Using the Calculator

Tips: Enter the UPS load in VA (volt-amps), desired runtime in hours, and LiFePO4 battery bank voltage. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between VA and Watts?
A: VA (volt-amps) is the apparent power, while Watts is the real power. For sizing purposes, use the VA rating of your UPS.

Q2: Why use LiFePO4 instead of lead-acid?
A: LiFePO4 batteries offer longer cycle life, deeper discharge capability, and better energy density compared to lead-acid.

Q3: Should I add a safety margin?
A: Yes, consider adding 20-30% to the calculated Ah to account for battery aging and efficiency losses.

Q4: What's the typical voltage for LiFePO4 systems?
A: Common nominal voltages are 12.8V (1 cell), 25.6V (2 cells), or 51.2V (4 cells) for larger systems.

Q5: Can I use this for other battery chemistries?
A: The calculation works for any chemistry, but discharge characteristics differ. LiFePO4 can typically use 80-90% of rated capacity.