Calculating the Number of 12V 200Ah Batteries Required for a 5kVA Inverter

When it comes to powering a 5kVA inverter with a series of 12V 200Ah batteries, accurately estimating the number of batteries needed involves several steps and considerations. This article will guide you through the process and highlight the factors that can impact your calculation.

Step-by-Step Guide

Step 1: Convert kVA to Watts

The first step is to convert the inverter's power output from kilovolt-amperes (kVA) to watts (W). The conversion is simple and involves multiplying the kVA by 1000 to get the equivalent watts. Assuming a power factor of 1 for simplicity:

5 kVA 5 * 1000 W 5000 W

Step 2: Calculate the Total Energy Requirement

Next, determine the duration you wish to run the inverter. Let's say you want to run it for 1 hour. The energy requirement is calculated as follows:

Energy Wh Power W * Time h 5000 W * 1 h 5000 Wh

Step 3: Determine the Capacity of One Battery

Each 12V 200Ah battery has a total energy capacity:

Capacity Wh Voltage V * Capacity Ah 12 V * 200 Ah 2400 Wh

Step 4: Calculate the Number of Batteries Needed

To find the number of batteries required to provide the energy needed, divide the total energy requirement by the capacity of one battery:

Number of batteries Total energy required Wh / Capacity of one battery Wh 5000 Wh / 2400 Wh ≈ 2.08

Since you can’t have a fraction of a battery, you would need 3 batteries to meet the energy requirement for 1 hour.

Summary

For a 5 kVA inverter running for 1 hour, you would need 3 12V 200Ah batteries. Adjust the number of batteries based on the duration you require the inverter to run. For instance, for 2 hours, you would need 6 batteries.

Additional Considerations

While the initial calculation provides a basic guideline, it's important to consider the following factors to ensure reliable operation:

Real Efficiency and Load Sensitivity

The efficiency of the inverter and the expected normal and maximum load play significant roles. Most people run inverters to convert DC to AC to power AC devices. Depending on the actual devices you're running, you might require a larger inverter for startup current. If you don't run AC devices requiring 5kW, using a smaller inverter might be more efficient for the power to run the inverter itself.

Battery Specifications and Chemistry

The specific capacity and efficiency of the batteries you plan to use are critical. A 200Ah battery might provide 1 amp for 200 hours, while another 200Ah battery might supply 400 amps for only 1/2 hour. Different battery chemistries produce various voltages, ranging from 1.2V for NiMH to 3.85V for lithium-ion.

Environmental Factors

The operating environment significantly impacts battery performance and lifespan. Batteries can drop in efficiency and lifespan outside their rated temperature ranges. Cold temperatures typically require more batteries, while hot conditions also demand additional capacity. Certain batteries may not function optimally in extreme temperatures, such as arctic cold or desert heat.

By considering these factors, you can ensure that your inverter setup meets your needs safely and efficiently.