Calculating Ampere-hours (Ah) from Watts: A Guide

Introduction:

In this blog, we will explore how to calculate the number of hours you can run a device using a battery’s capacity in Ampere-hours (Ah) and Watts (W). Specifically, we will consider the scenario of running a hair dryer through a power inverter using a 12V 100Ah battery in a van.

Calculation Formula:

To determine the number of hours you can run a device, we will use the following formula: Wh / V, where Wh represents Watt-hours and V represents Volts. In this case, we need to calculate the Ah (Ampere-hours) by dividing the Watt-hours by Volts.

Example Calculation:

Let’s assume we have a 100W hair dryer and a 12V battery with a capacity of 100Ah. Using the formula mentioned above, we can calculate the Ah value as follows:

100Wh / 12V = 8.333Ah

This means that for a 100Ah battery, you can run the 100W hair dryer for approximately 8.333 hours.

Note on Watt-hours:

It is important to understand that Watt-hours represent the amount of energy consumed per hour. Therefore, 1 watt-hour signifies 1 watt of power expended for 1 hour.

Using the Calculation:

Taking the example further, if you had a device that consumed 200W, you can use the same formula to determine the running time:

200Wh / 12V = 16.667Ah

In this case, with a 100Ah battery, you can run the 200W device for approximately 6 hours.

Battery Considerations:

It is essential to consider that the calculations above assume a fully charged battery and the ability to consume 100% of its power. While this is possible with certain battery types, such as LiFePo4, it may not be the case for regular lead-acid batteries.

Conclusion:

Understanding how to calculate the running time of devices using Ampere-hours and Watts can be valuable for planning and managing power consumption when relying on batteries. By using the provided formula and considering your battery’s capacity, you can estimate the hours of usage accurately.

Tags: battery capacity, power consumption, Ampere-hours, Watt-hours, battery efficiency, power inverter