How Long Can Two 12V 100Ah Batteries Last When Used on a 24V Inverter with a Deep Freezer?

In this article, we will explore the runtime of two 12V 100Ah batteries when used on a 24V inverter to power a 195-liter deep freezer. This analysis involves calculating the energy consumption of the freezer and the total available energy from the batteries. Follow our step-by-step guide to determine the duration of operation.

Step 1: Calculate the Freezer's Power Consumption

Before we can determine the runtime, we need to estimate the power consumption of the freezer. A typical deep freezer might draw around 150 watts (W) when running continuously. Since freezers often cycle on and off, we will use this conservative estimate for our calculations.

Step 2: Calculate Daily Energy Consumption

Using the formula for energy consumption:

Energy kWh Power kW × Time h

We can calculate the energy consumed by the freezer over a 24-hour period:

Energy 0.150 kW × 24 h 3.6 kWh

Step 3: Calculate the Battery Capacity

Two 12V 100Ah batteries connected in series create a 24V battery with a capacity of 100Ah. The total energy capacity of the batteries in kilowatt-hours (kWh) is calculated as follows:

Battery Capacity kWh Voltage V × Capacity Ah / 1000

For the two batteries:

Battery Capacity 24V × 100Ah / 1000 2.4 kWh

Step 4: Determine Runtime

To find out how long the batteries can power the freezer, we divide the total energy capacity of the batteries by the energy consumption of the freezer:

Runtime h Battery Capacity kWh / Energy Consumption kWh

Runtime 2.4 kWh / 3.6 kWh ≈ 0.67 h or about 40 minutes

Conclusion

Based on the calculations, two 12V 100Ah batteries connected in series would last approximately 40 minutes before being fully discharged when powering a 195-liter deep freezer on a 24V inverter for continuous use.

Important Notes

Depth of Discharge (DoD): It is typically recommended not to discharge lead-acid batteries below 50% of their capacity to prolong their lifespan. If following this guideline, the usable capacity would be halved, reducing the runtime significantly. Efficiency Losses: The inverter will also have efficiency losses, typically around 10-15%. This means you may get even less runtime in practice. Actual Freezer Consumption: The actual energy consumption of the freezer may vary based on factors such as temperature settings, ambient temperature, and how often the compressor runs.

If you have specific details about the freezer's energy consumption, we can refine these calculations further!