Lithium Battery Size Calculator For Inverter

Battery Capacity Formula:

\[ \text{Battery Capacity (Ah)} = \frac{\text{Load Power (W)} \times \text{Required Backup Time (h)}}{\text{Battery Voltage (V)} \times \text{Depth of Discharge} \times \text{Efficiency}} \]

Load Power:

watts

Required Backup Time:

hours

Battery Voltage:

volts

Depth of Discharge:

decimal (0-1)

Efficiency:

decimal (0-1)

Required Battery Capacity:

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1. What is Lithium Battery Sizing?

The lithium battery size calculator determines the required battery capacity (in ampere-hours) needed to power an inverter system for a specified duration. It accounts for load power, backup time requirements, battery voltage, depth of discharge, and system efficiency.

2. How Does the Calculator Work?

The calculator uses the following formula:

\[ \text{Battery Capacity (Ah)} = \frac{\text{Load Power (W)} \times \text{Required Backup Time (h)}}{\text{Battery Voltage (V)} \times \text{Depth of Discharge} \times \text{Efficiency}} \]

Where:

Load Power — Total wattage of devices to be powered
Backup Time — Desired runtime in hours
Battery Voltage — System voltage (typically 12V, 24V, or 48V)
Depth of Discharge — Fraction of battery capacity that can be used (typically 0.8 for lithium)
Efficiency — System efficiency (typically 0.85-0.95 for inverter systems)

3. Importance of Proper Battery Sizing

Details: Correct battery sizing ensures your system can handle the required load for the desired duration while maximizing battery life and avoiding over-discharge.

4. Using the Calculator

Tips: Enter all values accurately. For depth of discharge, use 0.8-0.9 for lithium batteries. Efficiency typically ranges from 0.85 to 0.95 for good inverter systems.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical depth of discharge for lithium batteries?
A: Lithium batteries can typically discharge 80-90% of their capacity, compared to 50% for lead-acid.

Q2: How does battery voltage affect capacity?
A: Higher voltage systems require fewer amp-hours for the same watt-hour capacity (e.g., 100Ah at 12V = 50Ah at 24V for same energy).

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

Q4: How does temperature affect battery capacity?
A: Lithium batteries lose capacity in extreme cold - consider 10-20% derating for temperatures below freezing.

Q5: Can I use this for lead-acid batteries?
A: Yes, but use 0.5 for depth of discharge and account for lower efficiency (0.8-0.85).