Ten Tips About Your RV's Electrical System


It began with wondering where to plug in my laptop while boondocking. I knew there was some kind of "thing" we had to switch on and that it only powered a few outlets - but what was it? The monitor panel was still a mystery to me and I stared at all the LED displays, the "on-off" buttons, and the labels. Ah, there it is! On the display to the far right of the panel was a switch clearly labeled, "Inverter". 

The Inverter

Very simply put, the inverter takes energy from the battery to power outlets in the coach. There's a bit more to it than that, but that's all I really wanted to know at that moment. I switched it on and, "voila!" - power to the outlet in the kitchen and one in the front of the coach, where I plugged in my laptop and got to work. 

Considering I am a writer, keeping my laptop charged is pretty important to making my article deadlines. So learning more about the inverter was based out of necessity rather than curiosity. I wondered if it had to be serviced or if I had to change parts to keep it working or, whatever. It seemed like a good idea to learn about this important device. So here's an "abridged" version of your RV's electrical system and how it works.

Let's start with the inverter. In an RV, an inverter takes the direct current (DC power) from the battery and transforms it into alternating current (AC power). Alternating current is the type of power in your home electrical outlets, and the type of power most of your appliances and devices use. So, without an inverter, the battery doesn't help much. It's kind of like, I speak Chinese and you speak German - we really need a translator to communicate. That's what the inverter does, it "translates" the DC power of the battery to the AC power for your appliances. 

But that's just the beginning to what an inverter can do. When the RV is plugged into shore power, the AC shore power flows through the inverter to power your appliances - in this case, the inverter doesn't need to transform it from DC. Rather, it simply transfers the power from the shore power hook up to your appliance outlets. Additionally, the inverter, if equipped with a converter function, can also translate the AC power from a generator or shore power to the DC battery power for storage - recharging the battery. 

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Since batteries have a limited amount of stored power, the run time of appliances is limited to the size and charge level of the battery. And that's when the generator or shore power can really come in handy - to either keep the battery charged or to shoulder the power draw from appliances.

Large appliances like air conditioners, water heaters, or microwave ovens need a long, heavy draw of power and may have a very short run time (or may not run at all) when trying to draw power from a battery. Those big appliances require a generator or shore power to provide a large and steady power supply for them to function properly - this is when the inverter goes into "transfer"  mode, transferring the power from the generator or shore power directly to the outlets and appliances rather than drawing from the battery.

If you are like me and travel with a lot of electronics that need to be recharged, it's good to know the type of inverter you own. There are two basic output types: modified sine and pure sine wave. Most inverters are fine for running TVs, satellite dish receivers, computers, and printers. However, some types of inverters (modified sine wave) may not be compatible with rechargeable power supplies likes cell phones, drills, and the like. Before you plug in that phone or laptop charger make sure you know if it's safe for your device. (The information about your inverter should be with all of your RV documentation. Give it a quick browse to make sure you know the type, size and output). 

The RV Battery Bank

In order for the inverter to do its transforming work, the battery bank has to be charged up. RVs typically have multiple batteries linked together to form a power bank. Most newer RVs are equipped with a converter  that can charge up the battery(s) from shore power. It takes the AC shore power and converts it to DC battery power. But there are several other ways to keep a bank of batteries charged.

The first is simply turning on the RV's engine. Most coach batteries can be charged - to a limited extent - by driving. Since the amount of charge the chassis alternator can generate for the coach battery depends on a lot of variables, it's not the best option. A better method is to run the generator to recharge the battery. Usually diesel or propane powered, the generator produces electricity that can be stored in the battery (or transferred through the inverter to supply the coach appliances and outlets). A third method is using solar panels. If you have solar panels installed, they will contribute the power they generate from the sun to help keep a battery charged. The last option, is taking the battery out of the RV and hooking it up to a battery charger.

Although there is not much maintenance you can do for your inverter, your RV batteries need special attention. When we learned that it was important to never let the batteries drop below half - charge we monitored it carefully. Unfortunately,  the 13.4 "fully charged" reading we took while plugged into shore power seemed to indicate that a reading of 6.2 volts would be "half-charged". Not so. Half-charge of our battery bank happens at about 12.5 volts. 

There's a process of determining electrolyte levels in the battery using a hydrometer to find the true level of a battery's charge but let's just say, never let them drop below 12.5 volts. If they do drop as low as 10.5 volts a chemical reaction within the battery can permanently damage it, rendering it useless. (yes, this happened to us since we thought "7 volts" was half of 14. We had to buy two new batteries - an expensive lesson!).

So, part of the special attention batteries need is to monitor their charge level. If you have the type of battery that requires water, you must also check the water level in the battery. See your battery manufacturer's recommendations on the level of water and make sure you use ONLY distilled water. You may, however, be one of the lucky ones and have the sealed, "no maintenance" type! 

Finally, if you won't be using your RV, switch the battery disconnect feature to "off" to prevent any draw that might drop it to dangerous levels. You'd be surprised at how much power an RV can use even when it's in storage. Micro-electrical needs from appliances and monitors put a continual draw on the battery and can drain it completely. Better to just switch the battery off if you are not using your RV.   

The electrical system in your RV is built to make camping more comfortable, but it doesn't work exactly like the electrical system in your home. So getting to know the pieces of your RV electrical system and how they work together to provide power will help you understand just how much "glam" you can add to your camping experience.

Here's a quick recap of your RV’s electrical system:

  1. An inverter transforms the DC power in the battery to AC power your appliances can use. 

  2. An inverter can also transfer AC power directly from shore power (or generator) to your appliance outlets. 

    • If you are boondocking, you will be using either battery power through the inverter, or generator power through the inverter.

    • If your RV is plugged into shore power, it sends AC current through the inverter to power your appliances.

  3. The coach battery charge must be monitored to stay above half-charge.

    • Recharge your RV battery if it approaches 12.5 volts

  4. Some inverters have a feature (a converter) that can act as a battery charger, turning the AC power from the generator or shore power into stored DC battery power. 

  5. Your RV solar panels also help to keep the coach battery charged but don't typically generate enough power to run the electrical system.

  6. If you have a battery that requires water, you will need to check the water level regularly and, when needed, add distilled water.

    • If you have a "no maintenance" battery - you're all good!

  7. If you will not be using your RV, switch the battery supply to "off" to conserve the battery.

  8. Check your RV documentation to learn about the type and function of the inverter installed in your RV. Make sure it is compatible with re-charagble devices you plan to take along.

  9. And while you have the documentation pulled out, read the information about your RVs battery(s) - every RV is a little different.

  10. To know how much power you are using, add up the power draw from each appliance you are using simultaneously (there is a label on most appliances near the power cord that indicates its power needs).