RV FEATURE
We ’ ve always looked at 12V power systems in terms of ‘ amps in ’ and ‘ amps out ’, but that is only half of the equation . This article will explain why understanding your electrical system and managing power usage is a case of forgetting about amps and focussing on watts .
WHAT ’ S A WATT ?
A watt is a unit of power used to qualify the rate of energy transfer . That may sound like a mouthful but think about those last two words : energy transfer . Everything about your RV ’ s electrical system can be described in terms of energy transfer . A battery charger transfers energy from the power grid into your batteries to be stored and used later .
Similarly , solar panels transfer energy from the sun into a solar controller to recharge your batteries . When you turn on a light , it works by transferring stored energy from the batteries , through the wires , into a diode , which emits energy in the form of photons or light .
It may look complicated but all that this gear does is manage power in and out of your batteries .
Think of a watt as you would a litre of water . You can fill a large water tank from a mains tap or by capturing rainwater and channelling it into the tank . That water can then be used to water a garden by connecting a hose and sprinkler to the tank . The tank will hold a certain amount litres of water and the rate at which you fill it and empty it will determine how quickly you will fill it or empty it .
WHAT ’ S WATT ’ S LAW ?
Watt ’ s Law defines the relationship between power , voltage and current . It is the key to understanding how your RV electrical system works at the most basic level . Watts Law states that Watts = Volts x Amps .
So if you have a 12V , 25A battery charger , using Watt ’ s Law we can calculate how many watts it will put into your battery . Twelve volts multiplied by 25A equals 300W . It ’ s that simple !
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