Managing Energy Use for Boondocking in a Big Rig

Before we hit the road a few years ago, we knew we wanted to travel one day, when we retired and our daughter was grown. It hadn’t yet occurred to us that we didn’t have to wait to pursue our travel dreams. Until one day it dawned on us: Why not travel now? What were we waiting for? Randy worked as a remote employee while I stayed at home with Ada, who had not yet started school. So we sold our dream home and all of our stuff, and purchased a 2019 Keystone Montana High Country fifth wheel.

For almost two years, we have hiked snow-capped mountains, watched glorious sunrises, kayaked in alpine rivers, enjoyed campfires by the ocean, and cultivated friendships along the way. RV life has brought us one amazing adventure after the other and the cherry on top is the freedom that this lifestyle offers. And we never feel more free as when we’re boondocking.

But successfully camping off-grid in a rig as large as ours requires conservation and a focus on the critical. We’ve learned some tips along the way.

Understanding your Energy Usage

The first step to managing your energy is to understand how energy is different from power. RV electrical gadgets all require power to operate, which is measured in Watts (W). Energy is power used for a period of time, and is calculated in kilo-Watt-hours (kWh). Both power and energy drive different parts of the electrical system. 

Peak power is determined by adding up the Watts of all devices that can operate at the same time. This determines how large of an inverter to install. If the inverter is not big enough, it will overload and shut off. 

Daily energy usage drives the requirements for the size of your battery bank and solar arrays.  An ideal system would have a solar array capable of collecting 100% of the RV’s 24-hour energy requirement in an 8-hour period. The battery bank should be able to store 16 hours of energy.  If the solar array does not collect enough energy or the battery bank is not large enough, then the batteries may not have enough stored energy to make it through the night.

What should you consider in determining what energy features or add-ons you need?

The main consideration for determining energy features and add-ons is that they should be based on your needs. Electrical gadgets all require energy to operate, and every Watt that powers your infrastructure reduces the available battery time for everything else.

There are four broad areas you need to consider: energy consumption, power distribution, energy storage and power generation.

Energy consumption:

Write out a list of every device in your RV that uses power and energy. Identify which of those devices are truly must-have while you’re off-grid. For instance, your fridge is a must-have, but you might decide that you can do without a coffee maker for a few days and just make coffee over a fire. Once you have your list of must-have devices, figure out how much power and energy those devices take.

Your list may look different. From here, we add up how much energy our gadgets consume  each day, and we have a basic idea for how much energy we need to store while we boondock.

We have also found that the two most helpful gadgets for understanding energy usage are an AC power meter and a DC battery meter. A power meter can be added to the RV load center to accurately measure real time power usage. Nicer meters will even calculate accumulated energy usage over time. A battery meter can be added to the main negative connection on the battery bank to accurately account for all energy going in and coming out of the batteries. This keeps track of charge level, time remaining to full safe maximum discharge, charge/discharge rates (Amps), and cycle counts.

Power distribution:

A typical off-grid power distribution system will use batteries to power an inverter, which powers all the AC loads. Determine the size of your inverter by the peak power demand of your RV. The more ruthlessly you cut your “must have” device list, the smaller an inverter you can use. We use a 3 kW inverter from Victron Energy.

When you power the entire RV with an inverter, it’s critical to include some sort of automatic transfer switch to control whether power comes from the inverter or the shore power plug, and  ensure that no power from the inverter can pass to the shore power plug.

Energy storage:

Off-grid success hinges on the battery bank. General wisdom says to buy the best batteries you can afford. Lithium ion batteries are the gold standard for the modern RV. The real question is, how many batteries do you need? Battery capacity is quantified in Amp-hours (Ah). A perfect 100 Ah battery can supply 1A for 100 hours or 50A for 2 hours. Most RVs have a 12V DC system, so 12V batteries can be added in parallel to increase the storage capacity (Ah) rating of the array, which will increase the amount of time the batteries can operate the RV. Lithium ion battery systems operate at 14.4V so we use 4 x 100 Ah Battleborn batteries to store the 5.76 kWh hours we need to keep our RV powered at night.

Power generation:

There are two main ways to generate power in an RV: solar panels and generators (gas or propane). We use a 6-panel, 960W solar array with a 2200W generator to keep the RV powered off-grid. Most generator-powered rigs use the generator to directly power all AC devices when it is running, which requires a 5 kW generator. We only use our generator to charge the batteries through a dedicated generator input to the rectifier. This allows us to use a much smaller generator and only use the inverter to power our devices.  In addition to being convenient, it serves to protect our sensitive electrical devices from dirty generator power.

How do you stretch your energy consumption?

The largest consumers of energy in an RV are air conditioners, water heaters and refrigerators.  A single air conditioner will use about 1.2 kWh every hour, so only run the air conditioning when it’s absolutely necessary. Most of the time, we just go without it. The water heater can use more than 1.5 kWh every hour, but it’s easy to eliminate by burning propane to keep the water hot.  Many rigs have RV refrigerators that also burn propane for the energy necessary to keep food cold, but more and more people have residential refrigerators like ours. The best way to lower the refrigerator’s energy usage (3 kWh every hour) is to stay out of it as much as possible. Being mindful about opening the fridge can reduce the energy requirement by 10-20%. I usually prepare meals ahead of time that are easy to put together and require minimal cleanup––which translates to less time opening the refrigerator and less time running the water pump.

Water conservation is vital when boondocking, not only because you have limited fresh water, but also because your water pump consumes a lot of energy. There are many ways to help reduce the amount of time you run your water pump. For instance, take fewer showers (or no showers: hello dry shampoo and venture wipes), trickle the water when washing your hands or dishes, use disposable dishware and collect the water you use into a collapsible wash basin to flush your toilet. Also, buying a few gallons of drinking water helps conserve water and energy since you’re not activating your water pump every time you get thirsty.

While other devices don’t seem to use much power and energy individually, they can add up. LED Lights, for example, only use about 2.5W each. But if we left all 28 of our lights on for eight hours a day, we would use more than 0.5k Wh, or about 10% of our daily solar production. So use daylight as much as possible. Another thing to watch out for are unused electrical devices that draw power even when they’re not in use. We recommend unplugging any unused devices while you’re boondocking.

Another way to optimize your energy usage is by orienting your RV to take advantage of seasonal conditions. For instance, parking north-south in the summer reduces the RV surface area exposed to the sun during the heat of the day, making it easier to keep cool with just the roof fans. An east-west orientation in the winter helps the RV stay warmer during the day by exposing one side directly toward the sun. Parking in shade is a bit of a catch-22 if you have solar panels--on the one hand, it might help you stay cool, but on the other, you bank less energy.

Lastly, bridge the gap! Use a small generator to supplement days when it’s overcast and your solar collection suffers. A 2200W generator can charge the DC system at a rate of 160A at 12V.  This can add about 1kWh per 30 minutes of operation to the system.

If you’ve made it to the bottom of this article––congratulations! You’ve learned everything you need to get started managing your energy usage off-grid. And that means you can plan a stay almost anywhere your RV can travel, hook-ups or no.

Jama Maples and her husband travel in a 2019 Keystone Montana High Country.