1. What is Battery Backup System Sizing?

Battery backup system sizing determines the appropriate capacity (in kWh) needed to support your electrical load for a specified duration, accounting for depth of discharge limitations.

2. How Does the Calculator Work?

The calculator uses the equation:

Where:

• Peak Load — Maximum power demand in kilowatts (kW)
• Duration — Desired backup time in hours (h)
• DoD Inverse — Inverse of Depth of Discharge (1/Max DoD)

Explanation: The equation calculates the total energy storage needed while accounting for the fact that batteries shouldn't be fully discharged to prolong their lifespan.

3. Importance of Proper Sizing

Details: Correct sizing ensures your backup system can handle your power needs without being oversized (which increases cost) or undersized (which reduces reliability).

4. Using the Calculator

Tips: Enter peak load in kW, desired duration in hours, and DoD Inverse (typically 1.25 for 80% DoD). All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is Depth of Discharge (DoD)?
A: DoD is the percentage of battery capacity that has been used. Most batteries have recommended maximum DoD (e.g., 80%) to prolong lifespan.

Q2: How do I determine my peak load?
A: Sum the wattage of all critical loads you want to power simultaneously, then divide by 1000 to get kW.

Q3: What's a typical DoD Inverse value?
A: For lithium-ion batteries (80% DoD), use 1.25. For lead-acid (50% DoD), use 2.0.

Q4: Should I add a safety margin?
A: Yes, consider adding 10-20% to the calculated size to account for efficiency losses and future load growth.

Q5: Does temperature affect sizing?
A: Yes, cold temperatures reduce battery capacity. In cold climates, you may need to increase system size by 20-30%.