1. What is Battery Capacity Calculation?

The battery capacity calculation determines the required ampere-hour (Ah) rating of a battery bank needed to power your inverter load for a specified backup time. This considers factors like inverter efficiency and recommended depth of discharge to prolong battery life.

2. How Does the Calculator Work?

The calculator uses the following formula:

Where:

• Inverter Load Power — Total wattage of connected devices
• Backup Time — Desired runtime during power outage
• Inverter Battery Voltage — System voltage (typically 12V, 24V, or 48V)
• Depth of Discharge — Recommended discharge limit (typically 0.5-0.8)
• Inverter Efficiency — Conversion efficiency (typically 0.85-0.95)

Explanation: The formula accounts for energy requirements, system losses, and battery preservation factors.

3. Importance of Battery Sizing

Details: Proper battery sizing ensures sufficient backup time while preventing excessive discharge that can shorten battery lifespan. Undersized batteries may not provide enough runtime, while oversized systems are unnecessarily expensive.

4. Using the Calculator

Tips:

• Sum the wattage of all devices to be powered simultaneously
• For lead-acid batteries, use DoD of 0.5-0.8 (50-80%)
• For lithium batteries, DoD can be 0.8-0.9 (80-90%)
• Typical inverter efficiency ranges from 85-95%

5. Frequently Asked Questions (FAQ)

Q1: What's a typical DoD for lead-acid batteries?
A: 50% for starter batteries, 80% for deep-cycle batteries to maximize cycle life.

Q2: How does temperature affect battery capacity?
A: Capacity decreases in cold temperatures (about 1% per °F below 80°F/27°C).

Q3: Should I add a safety margin?
A: Yes, consider adding 20-25% to account for aging and unexpected loads.

Q4: How do I convert Ah to Wh?
A: Multiply Ah by system voltage (e.g., 100Ah × 12V = 1200Wh).

Q5: What's the difference between C20 and C10 ratings?
A: C20 is capacity over 20 hours, C10 over 10 hours. Use C20 for backup systems.