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  • Writer's pictureEthan Barr

know your electrical system

Most boats, yachts, RVs, and the like have two main electrical systems: DC and AC.

Now, what do those terms even mean? Well, DC systems usually run on lower voltage, like what you get from batteries. They're great for basic stuff like powering lights, electronics, radios etc.

On the other hand, AC systems use higher voltage, typically coming from shore power or onboard generators. They handle heavier-duty tasks like charging the DC batteries, powering the microwave and the water heater etc.

To move forwards we need to understand terms like volts, amps, and watts.

1)     Volts are the force of electricity, the higher the Voltage the further it travels.

2)     Amperage or amps are the rate of flow, a bigger wire can flow more through it.

3)     Wattage or watts represent the power produced when you multiply volts times amps.

There's also a term called resistance, but let's keep it simple for now, and stay out of that one.

To sum it up, you need 115 volts x 0.8 amps to power your wall phone charger, we can also say that your phone charger takes 92 watts (115x0.8 = 92).

Here's where it gets interesting. Every appliance or device has specific power requirements. Give it too little voltage or amps, and it won't work properly. Give it too much, and it might fry!

When there's an electrical issue, like a device not working, I'm often called to troubleshoot. The first step? Figuring out if it's an AC or DC problem.

Why does all this matter? Well, you don't want to get stranded, do you?

Let me explain; understanding your power consumption will save you that pain, which brings us to talk about Watts; Watts are our way to know if a Load is light or heavy, the more watts it takes the heavier it is.

For example, a fridge in your boat or RV will use the same amount of power (Watts) whether it's plugged into shore power (AC) or running off the batteries (DC), in this case let’s assume it takes 100 watts.

So, when you disconnect the shore power cord, that fridge is now going to draw its power (100 watt) from the batteries (your DC system).

Your batteries reserved capacity will shrink rapidly when you have many Loads (devices) running or if you have just a few but they are heavy (i.e take a lot of watts).


A practical tip: Make a list of all your appliances and their power needs. Separate them to AC and DC, this will help you manage your electricity usage and avoid running out of juice unexpectedly.

Additionally in the future, you might want to upgrade your system, maybe with more battery capacity or alternative charging methods like solar panels or wind vanes. Understanding your power needs now will make those upgrades easier and more effective later.

So, there you have it! A crash course in boat and RV electricity. If you find this helpful, let me know. I'd love to dive deeper into this topic!

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