Converting Amp Hours to Kilowatt Hours in a Marine Power System

With various measurements that represent the power within marine electrical systems, it’s easy to get confused when different units are used. Since batteries are represented by amp hours and certain electronics and other components use kilowatt hours, its essential to understand how to convert between the two.  

How to Convert Amp Hours to Kilowatt Hours 

Originally, boats were equipped with amp meters that would measure how many amps were being used on a DC system. This led mariners to focus on how many amps of power each appliance was using and therefore want to know how many amp hours (Ah) their batteries held. So, how can we convert Amp hours to kilowatt hours? 

Amp hours represent how much power is available over a certain amount of time. In the Ah equation, since power is being multiplied by a unit of time, this is a measure of energy. Similarly, kilowatt hours (kWh) are also a measurement of being multiplied by a unit of time.  

To turn Ah into kWh, you must multiply the number of Ah by the nominal voltage of the system. Generally, most marine systems operate on a 12V nominal voltage. However, with a LiFePO4 battery bank the nominal voltage is around 13V. 

 For a Battle Born 8D 12V 270Ah battery, the calculation to kWh would be multiplying 270Ah by 13V to get 3,510 watt hours (Wh), then dividing 3,510 Wh by 1,000 to get 3.5 kWh. 

Want to Learn More? 

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