How To Install an Inverter in Your RV
Our RV, a Grand Design Reflection 312BHTS Travel Trailer, did not come with an inverter already installed like some RV’s do. We’ve spent many nights in Walmart parking lots to break up long drives, and we’ve also gone boondocking a couple times. Both of those camping scenarios mean we have no electricity at the outlets in our rig because we’re not hooked up to an external power source. We needed a way to use the electricity stored in our RV’s batteries to power Brian’s CPAP and use a couple fans so we can all sleep comfortably overnight. Enter the power inverter – a handy device that converts electricity from a 12V battery system to 110V “household” electricity that can power things like TV’s, fans, and other regular appliances.
What We’re Installing
The two major components in this install are the power inverter and a power meter so we can see how electricity is being used. You can install either of these items without the other, but if you’re already in there digging into your wiring it’s a great time to knock both out at once.
I went with the EDECOA 1000W Pure Sine Wave Inverter for this install. There are two things that attracted me to this unit other than the price. First, it’s a “pure sine wave” inverter, which means it’s safe to use with sensitive equipment like a CPAP. A regular inverter has “square” power waves which can cause damage to some types of electronics. I didn’t want to fry my CPAP, so pure sine wave is the way to go.
Second, I really like all of the features on this unit. It has an on-board screen, power switch, super bright power indicator, and three outlets. It also has a “remote” that you could run and install somewhere useful, but I didn’t bother doing this as the unit itself is easily accessible where I placed it. Let’s not forget the best feature though – this inverter also has a relatively accurate little meter showing you how much juice is left in your battery!
Adding a power meter is completely optional, but I wanted to have a bit more insight into how electricity was being used when we weren’t on shore power. I found the Bayite Battery Monitor on Amazon, which not only has an awesome price but also a ton of great reviews. It has a nice bright backlight, comes with a very easy to read wiring diagram, and also includes a shunt. The shunt is a critical component in installing this meter and you’ll see a lot more about that down below. This meter also runs on very low voltage so I was able to use a telephone cable (remember those?) for all of the wiring it required.
I’ll explain more about what information the meter shows at the end of this install, but the short version is that it shows you how much power is being drawn from your battery and how quickly. This gives you a good sense of what you can run and for how long before your batteries are drained. That’s way better than guesstimating, and I can’t recommend it strongly enough. This is the perfect time to add a meter to your system, so just go ahead and get one with your inverter.
In addition to the two main components above, we’ll also need a few other things.
- A good pair of wire cutters/strippers. I LOVE this set: https://amzn.to/2IwJypT
- Four heavy-gauge (at least #4 AWG) electrical cables, three black and one red. I picked up two of these sets from Harbor Freight and used electrical tape to make one of the red cables into a black cable.
- Electrical tape
- A small tool set with screwdrivers, sockets, a utility knife, etc
- Zip ties
That should about do it, so let’s get started!
How To Install an Inverter in Your RV
Before we get started, a disclaimer. I am not a licensed electrician or RV technician. All of the instructions below show how I installed these items and aren’t necessarily the “professional” way it should be done. I know enough about electricity, wiring, and electrical diagrams to get by, and I consulted many websites, videos, and friends during this install. We are not responsible for any damages you may incur if you follow these instructions and something goes wrong.
Step 1: Our Work Area
This is what our forward storage compartment looks like when it’s empty. We call this our basement. Just to orient you a bit, our master bed is above those aluminum rails at the top and the nose of our RV is on the other side of that black wall.
Our battery cut-off switch lives here and is currently OFF in this photo. The battery cut-off switch is used to turn off the 12V power going into your RV. There are a few items that live on the “hot” side of this switch on our rig, including the tongue jack and brake controller, but your RV may be different.
Step 2: A Look at the Stock RV Battery and Wiring
This is what the stock RV battery on our rig looked like. I have since upgraded to two 6V golf cart batteries, but let’s save that for another post. The key takeaway from this photo is the existing wiring. You can see the standard red and black wires on the posts as well as two extra wires. Those two extra wires run up to a built-in solar charging port on this RV, and since I have no intention of ever using that style of solar I’m going to remove those during this project.
Step 3: Finding the Frame Ground
The frame ground is key in this install because we’re actually going to be completely re-wiring the way the negative (black) cable runs from the battery to the rest of the power system. The power meter requires a shunt to be installed into the negative cable’s route. The shunt gives us a couple points to attach wires for the meter, so I wanted to bring all of that inside the basement so it would be protected from the elements.
The stock wiring has the negative battery terminal connected directly to this screw on the frame to ground the system. Our new wiring is going to go from the battery to the shunt in the basement, then back out here to the frame ground. More on that soon.
Step 4: The Stock RV Battery Cut-Off Switch
We aren’t modifying the wiring at the battery cut-off switch in this install, but we are going to use it as a convenient place to tie into the positive wiring. The power meter also requires a wire added here so it can read power consumption. More on this soon as well.
Step 5: Opening Up Our Work Space
The black cover from the first photo is just some felt stapled onto a flimsy piece of board. This is secured to the framing in the photo with a few screws, so I just took those off to expose the wiring up front. We’re going to do a lot of things in this area. Unfortunately, there is also fiberglass insulation in here. You’ll want to minimize how much you touch this stuff. The tiny little fibers will stick to your skin and make you itch like crazy. If you’ve never encountered insulation before, consider yourself lucky!
In the bottom left of this photo you can see a wire loom coming up from under the nose to the outside wall. This loom contains the two wires for the solar charger. I need to use the hole that this come up through for my new, thicker negative cables, so I’m going to remove that whole loom and wires. Just unhook the wires, yank everything through, and let’s keep moving.
Step 6: The First New Negative Cable
With the solar charger wires and loom out of the way, I fished the new negative cable up from the front. This cable will be the only thing attached to the negative terminal on the battery. Remember from above: the negative cable used to go directly to the frame ground, but now it’s coming in here first.
Step 7: Installing the Shunt
The cable with the shunt attached is the same one from the previous step. I also had to run a second cable through that same hole. This second cable will go from the other end of the shunt and back out to the frame ground. If you’re not installing a meter you won’t be adding a shunt and won’t need to run two new negative cables like this. The meter adds some complexity like this, but the ability to see in-depth power usage is worth the effort.
Step 8: Wiring Up the Power Meter
1. This is the backside of the power meter and the instructions that came along with it. As mentioned previously, I’m using a telephone cable for all of these connections. Not only are the wires sufficient for the low voltage the meter requires, it’s also really convenient to have the wires already bundled together. This makes running the wires super easy.
2. Do you want to know why I love those wire strippers I linked to above? They handled these tiny little wires with no issues whatsoever. Stripping wires of this size can be tricky because it’s so easy to cut right through them. That pair of wire strippers took off the end of these three wires in about 10 seconds flat with no mistakes. You want these wire strippers, trust me.
3. Here are three of the four wires connected to the power meter. You can see in the wiring diagram that the meter requires four wires. That fourth wire, the red one, has to run to a completely different part of the basement from these three (the cut-off switch), so I decided to run that one separately.
Step 9: The Power Meter Installed
I opted to install the power meter on one of the aluminum beams that runs across the top of our basement. Since I had never seen this unit powered on, I actually installed it upside down without knowing it! You can see the red wire coming out of the side as well as the second telephone cable snaking down on the left. That’s the one running over to the cut-off switch.
Step 10: “Hacking” a Power Cable
I needed three new black cables for this install. The two sets I bought at Harbor Freight came in black and red pairs, so rather than buy three sets to get three black cables, I just added some electrical tape to one of the red cables to denote that it’s being used on the negative side of the system. Black and red cables are identical except for their colors so this wasn’t strictly necessary. This is, however, a good thing to do if you ever need to use a cable for the “wrong” thing. If I get into this wiring in the future, or someone else is in there for some reason, it will be nice to know that this cable isn’t actually being used as a positive cable.
Step 11: All of the Negative Cable Wiring
This image covers a LOT, so let’s just break it down a bit.To start off, this is the new negative cable from step 6, the shunt and second black cable from step 7, the other end of the power meter wires from step 8, and our new not-red-but-black cable from step 10. They all converge on this one spot at the same time. I used a couple zip ties to attach the shunt to the top edge of the frame. It ended up being a nice solid place to work from and keep everything from flopping around in the nose area.
The labels in the photo are pretty self-explanatory. The black cable attached to the bottom of the shunt is from the negative battery terminal. The black cable on the top of the shunt heads left and out to the frame ground. The other “black cable” on the top of the shunt will attach to the inverter in a couple steps. Finally the meter wiring attaches to the various points on the shunt. This wiring is the whole reason we’re adding a shunt. Note: the skinny red wire shown here isn’t being used, I just forgot to cut it off before taking the photo.
Step 12: Additional Cut-Off Switch Wiring
As I said before, we’re not modifying the cut-off switch in any way, but rather just using it as a convenient place to tie into the hot (red) side of the wiring. The new red cable is going to go to the positive terminal on the inverter. The skinny little red wire is the fourth connection that the power meter requires. One thing to note here: I attached my new wires on the “hot” side of the cut-off switch so the inverter can still get power even if the cut-off switch is turned off. If you want it to be on the “cold” side of the cut-off switch, simply attach your wires to the other terminal.
Step 13: Hooking Up the Inverter
A lot happened between Steps 12 and 13, but it’s really just putting things back together. I re-attached the cut-off switch to the black wall. The black wall was then put back up after a bit of a struggle (it’s 8 feet long and floppy!). I then figured out where I could place the inverter so the mounting screws would hit one of the vertical frame pieces and put one screw in so I could test everything. The negative and positive cables for the inverter were fed over the top of the black wall and attached to the inverter’s thumb screws.
After putting all that back together, it was time to test my wiring. I grabbed a portable fan and fired up the inverter and… it all worked on the first try! With the fan now blowing much-needed air it was time to take a look at the power meter.
Step 14: Power Meter Testing
This is when I first noticed that I had installed the meter upside down. After flipping it back around I was able to see how power was moving around my rig. With shore power turned off and the fan plugged into the inverter, these were my readings. The upper left number tells you the voltage remaining in your battery and should read between 12 and 13V at a full charge. I’m still not 100% on what the upper right number is telling me to be honest, but I know it isn’t the critical one in this setup. The bottom left number is the one we’re most interested in.
At the end of the day, your battery has a finite amount of power it can provide. The more electrical items you have turned on, the more watts are being drawn, and the faster your battery drains. In this photo my system is draining 52.7W from the battery with all the standard 12V appliances running plus the inverter and the fan I used for testing. This number will never be 0 in an RV because there’s always something running on your 12V system. Our fridge, LED lighting, radio (which even draws a little when it’s off), vent fans, slide and awning motors, thermostat, tongue jack, and braking system all run on 12V and several of those are always drawing a little bit.
After hooking this meter up I was able to see how much my CPAP and fans draw and calculate how long they can run. Spoiler alert: with two 6V golf cart batteries, it’s a pretty long time! The stock 12V “RV/Marine” battery in the photos above was good for about a night but not much more.
Step 15: Everything In Place
Here’s an angle that shows everything installed in the basement. This inverter has to be installed vertically or horizontally for proper function. The photo in Step 13 with it at an angle is not an option according to the instructions that came with the unit. You can also see where the power meter is in relation to everything else. This is as much as you need to do to install your inverter, but I wanted to go one step farther to make the power a bit more accessible when I needed it.
Step 16: Getting Power Inside
I wanted to have easy access to the inverter’s power when boondocking, so I came up with the idea of running the cable from a power strip down into the basement. The closet on my side of the bed is located directly above the ceiling in front of the power meter so this seemed like the perfect place. I found a power strip and cut the plug end off of the cable (to minimize the size of the hole I’d need). I then drilled a hole slightly larger than the cable up into the floor of the closet and ran that cut cable back down through the hole and into the basement. After attaching a new plug onto the end of that cable, I now have a somewhat-permanent way to access the inverter from right next to my bed where I need the CPAP.
The bonus to using a power strip in this way is that I can power more than just my CPAP. Erin and I like to have moving air when we sleep, so we have a little fan that we can plug into the strip as well. If we’re stopped somewhere muggy or warm, we can also run an extension cord down the hall and plug a fan in for the kids as well. We have also used the power strip to run the TV in the bedroom a few times when we’ve stopped on longer moving days and just want to relax for an hour or two.
And that’s about it, you now have an inverter and can use your battery to power all sorts of things in your rig! Hopefully you found this guide useful. If you have any questions, let us know on Facebook or Instagram and we’ll see if we can help!