Since this post, we upgraded from the 2000W to the 3000W Inverter. Everything here is still accurate, but with DC wiring rated at 400A.
You can find all of the components in the Inverter / Batter section of our Amazon Store here: amzn.to/3eUZXAu The links below have also been updated.
Want to run your TV, Coffee Maker, Microwave, etc using only battery power? We did! When boondocking, it was such a pain to have to fire up the generator just to make a pot of coffee or watch our night time TV. This Inverter project was in the plans from day one. Getting it done, however, took a LOT of research and planning. It's such a big project we needed to do it in non-disruptive stages so we could still live our lives in the rig. This video and article covers how we did just that!
NOTE! This is NOT an instructional course on how to install an inverter. If you are not comfortable with working on electrical systems and components, please seek a trained professional to do your instal.
In this post, I will go over the inverter project and even cover some of the nitty-gritty details we glossed over in the video. So let's jump right in!
Why do we need an Inverter?
First, let's look at the two types of power in an RV:
- AC – Not to be confused with Air Conditioning, AC stands for Alternating Current. It's the type of power that standard sticks and bricks homes use for power. Anything that plugs into a standard wall outlet uses AC power: Coffee Maker, Television, Blender, etc.
- DC – Direct Current – This is the kind of power batteries provide.
Typically, in an RV, DC power runs lights, fans, hydraulic slides, and hydraulic jacks, and maybe a few other things. DC power is also used in conjunction with propane for the furnace, hot water heater, and refrigerator (the latter two can also run on AC power).
Without an Inverter, the only sources of AC power are Shore Power (connected at an RV park, etc) and the generator. When connected to shore power, this place is just like a house. Plug in and run whatever you want. But what about when boondocking (no hookups) and you want coffee in the morning while watching the news? What about our normal TV time in the evenings? Before the inverter we'd need to run the generator, and that's a no-no early in the morning and late at night when you have neighbors. Even if we don't have neighbors, running the generator just to watch TV or make coffee is annoying!
An Inverter makes AC power using the DC power from the batteries, allowing us to have some of the creature comforts of home without the noise of a generator.
However, it takes a lot of DC power to run AC appliances for any acceptable length of time. The stock battery will not cut it!
Batteries (Step Zero)!
The best inverter in the world isn't worth squat without good batteries. So, the first order of business was to replace the single 12v battery that came with the RV. When it comes to batteries, there are no shortage of options. 6V, 12V, flooded cell, AGM, Lithium and on and on. This is not a battery tutorial, so I leave it to the reader to research the various types of batteries. That said, I chose to use 6V flooded cell deep cycle batteries by Trojan (Model T-105). These are true deep cycle batteries, meaning they can be discharged between 45% and 75% of capacity, which is key for RV / Inverter use. What good is battery capacity if you can only use 25% of it? While there are a lot of arguably better technologies on the market like AGM and lithium, these were more affordable at around $125 -$150 each, and they got great reviews. This was an upgrade we did in the first few weeks of getting our RV, and we'd spent enough on “stuff”.
So… Four big golf cart batteries, weighing in at 62lbs each for a grand total of 248 lbs! I wasn't comfortable just putting them in the front compartment without some kind of reinforcement of that area. A little online research showed that was a bad idea with compartments sagging and such. This was a simple solution: I got some angle aluminum from Home Depot, cut it into 3 sections, and secured them to the frame using self tapping screws.
Now, I have the issue of how to encase them. Lead Acid batteries emit hydrogen gas. Remember the Hindenburg? So, they have to be sealed AND vented. So, first step is I need a battery box. Figured I'd go to Home Depot and see if I could find something that might work. As luck would have it the 27 gallon tote seemed to measure up perfectly. The stock battery box was vented on the top to a hose connected to the front of the RV and also out the bottom, so I decided I could use the existing host, etc and figure out how to attach it to the new battery box. That part was crude and simple: I simply cut the top and bottoms off the stock box and sealed them to the lid and bottom of the tote with silicone. Boom! Vented battery box!
I secured the battery box to directly to the aluminum angles, which means the box is secured to the RV frame. Solid!
Installing the batteries was pretty straight forward. To get 12V (what the RV requires) out of 6v batteries, they get connected in series. Kind of like two 1.5 v batteries in the handle of a flashlight, the voltages add up to 12V. So, two sets of 6V batteries are then wired in parallel. This combo is called “series / parallel”. Again, not going into a deep dive on electricity here, but essentially the four 6V batteries with 225 Amp Hours of capacity each, wired this way yield 450Ah at 12V.
Since this article, we have upgraded to Battle Born Lithium. We currently have 3 in parallel, giving us 300Ah.
With the batteries in place it was time to think about how to install the inverter with as little interruption as possible to our daily life. In other words, I needed to do as much as I could without shutting off the power.
RV Project Golden Rule: If you're planning ANY kind of project on an RV, take your estimated time and multiply it by a factor of at least four! RV's have a way of throwing curve balls into even simple projects.
The basic plan was to put everything in place physically without hooking anything up. This allowed be to break the project into small manageable chunks, where each chunk could be accomplished in a day (including runs do home depot).
Step One – Control Cable Wiring
While a seemingly simple task, I knew this one would be a bear and I wanted to get it out of the way first. The cables for the OneControl system and other items in the “control cabinet” run back (from the control panel), to the left, and down through a VERY tight space. I tried fish tape and fiberglass fish rods, but nothing was making those tight turns in that tight space. So I used all of the cable slack behind the control panel and down in the basement to my advantage. I found a decent sized cable (one that could handle some pulling) that ran the path. I pulled as much of the slack as I could into the basement area, taped the two control cables (one was for the EMS) to said cable, and gently pulled the cables through. All of the trial and error involved took me the better part of a day (see RV Project Golden Rule above), but step one was complete!
Step Two – Inverter Mounting
Picking where to put the inverter is not as simple as it might seem. It's not just about finding a place to physically mount it, it's more about DC cable runs. DC power is very lossy. The longer the cables, the more power is lost. Think about a garden hose and how much pressure you have on the business end. Now, imagine that cable is a mile long. The pressure (analogous to voltage), will drop. Same thing happens with DC voltage. AC Power, on the other hand, is more analogous to pulsing the water back and forth, only moving the water a short distance over all and letting the alternation of the current on the other end to generate the power. Much less power loss equals less power needed and higher safety. The difference in these two types of power was the basis for the fight between Edison and Tesla… But I digress. Long story short, I needed short DC cable runs, so it made perfect sense to use some of the extra space in engineering (the front compartment – it's just fun to name areas in the RV) to mount the inverter.
The space on top of the generator compartment made the most sense, but I wanted to distribute the weight of the inverter across the whole compartment so it didn't sag. While I could have used aluminum angles again, I chose to just use wood two by fours. This part wasn't rocket surgery. Just cutting some wood, counter-sinking some self tapping screws to the generator compartment and fastening everything down.
Step Three – Control Panel Mounting
I wanted the control panel for the Inverter (and the EMS) to be in the same cabinet as the LCI OneControl panel. However, the stock location of the OneControl panel was dead in the middle, allowing no room for anything else. Luckily, the part of the back of the control panel that goes into the hole is low with a long section on the top. So, the control panel can be moved down and still cover the original hole. All I needed to do was extend the hole down about 1 inch and move the mount down. Easy! Then, it was just a matter of cutting a new hole for the Inverter control panel. One hole, four screws, done.
Step Four – DC Cables
At first I attempted to find some place to make custom cables for me. Interstate Batteries in Sarasota Florida made the battery interconnect cables (1 gauge / 1 awg), but they couldn't do 2/0 welding cable. I spent a few days calling around before I decided I would just make them myself. To do this, I needed a proper hydraulic crimper, the cables, and the lugs. Amazon Prime to the rescue! I was able to make custom cables, connect them to the inverter with the positive run going through a cutoff switch and 300 amp fuse. These cables would just hang on top of the battery box for the time being.
Note: I've seen videos online of people soldering connectors versus crimping. This is a bad idea. The point of a good connection is to make sure there is no insulating material in the connection prohibiting current flow. Air is an insulator, and if using this solder method, there is no way to ensure all of the air is out. A good crimp will. The right tools for the right job!
I also trimmed the excess length from the BTS (Battery Temperature Sensor) during this step and had it ready for connection day.
Step Five – AC Wiring
This step was also fairly simple and non-disruptive. The whole point in this step was to have two AC cable runs from the Inverter in the front compartment to the basement area, long enough to reach the ATS (Automatic Transfer Switch), and the distribution panel.
6/3 romex (6 gauge / 3 wire) is pretty standard household AC cable and can be purchased by the foot from any home improvement store. All I needed to do at this point was run the wires up over the basement (next to the furnace ducting), shield it, and connect it to the inverter. Just like the DC cables, the other end of these cables just hung lose waiting for connection day.
Step Six – CONNECTION!
Everything was in place and ready to be connected and tested, which consisted of:
Disconnecting ALL sources of AC and DC power: I shut off the shore power breaker and completely disconnected the shore power cable. I disconnected the DC side by using the disconnect switch (standard with the RV). I then took readings to make sure all AC and DC power was DEAD. The batteries still had power of course, but there's no way around that.. They are themselves power sources after all.
Battery Wiring: Like the other DC cables, I routed the inverter cables in through the top sides of the box and connected them to the batteries, leaving the top free for easy battery servicing.
AC Wiring: For this I just disconnected the cable that runs from the ATS to the distribution panel (both ends) and discarded that cable. I then connected the cable running to the Inverter IN to the OUT of the ATS, and connected the cable from the OUT of the Inverter to the Distribution Panel. Essentially, I just put the Inverter in line between the ATS and Distro.
Step Seven – TEST!
This was the exciting (and scary) part! Will it work? Will it catch on fire?
Testing essential consisted of:
- Inverter Test: With shore power still disconnected we turned on the inverter just to see if it would power up. Then we threw all of the breakers except the microwave. The instructions said use a light bulb, but we didn't have a light that's not DC powered and installed in the rig, so we used the microwave as a test (just basic power, not cooking!). Powered on! YESSSSS!
- Shore Power Passthru Test: Next it was time to connect shore power and make sure the inverter passes the AC power through and goes from Inverting mode (drawing from the batteries) to Charging Mode (power to the batteries). Another Success!
- Shore Power Loss Test: We disconnected shore power again to make sure the Inverter switched back the other way (Charging to Inverting). It worked! AMAZING!
- Appliance Testing!: Next, we tested restored all of the breakers and tested the TV, AppleTV, and Coffee Pot (just the important items!).
Step Eight – Configuration
Everything is working now, but there were a few tweaks to make. Essentially, we needed to tell the Inverter how to charge the batteries, when to give up, etc. The GoPower manual has recommendations for these settings, but I reached out to Trojan and asked for their input. They did make the batteries after all.
- Battery Type – Flooded Cell – Pretty straight forward. IT has built in settings for Flooded, 2 type of AGM, and custom (assume you would use this for lithium)
- Low Battery Cut Out – 50% is a general rule for true deep cycle flooded cell. You can go lower, but 50% is best for battery longevity. 11.95v was trojan’s recommendation, but I’ve had to play around with that value due to load voltage lowering. When you are actually inverting and drawing a heavy load from the batteries, the voltage will read lower than true voltage, causing the inverter to shut off prematurely. Still playing with this setting, but right now I have it set at 10.5V ed-hrvatski.com.
- Max Charge Time -12 hours
- Max Charge Rate – This setting is a percentage of total amps available for charging, which is 100 amps. The GoPower manual suggested calculation is 20% of Total Amp Hours. So, 450Ah would mean 90% or 90A (450 * 0.2 = 90). However, Trojan recommended 13%, which puts us at 60A – big difference
Update!: The settings above were for our flooded cell batteries. We've since upgraded to Battle Born Lithium and these are the new settings:
- Battery Type: Custom
- Absorb: 14.6V
- Float: 13.9V
- Equalize: 14.1V
- Low Battery Cut Out: Since the BMS built into the Battle Born will shut off the batteries at 0% usable, I set this at it's the lowest setting of 9.00V
- Max Charge Time: 12 Hours
- ABS Charge Time: 2 Hours
- Max Charge Rate: 100% – Since we have 3 in parallel, we can technically handle 300A charge. 100% on the 3000W Inverter/Charger is 125A.
Rough Cost Estimate
- Batteries: $600
- Inverter: $1380
- Fuse: $75
- Switch: $37
- Cable: $75
- Lugs: $19
- Crimper: $52
- 6/3 Romex: $110
- Other Misc: $100
Total (estimate) $2500
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This is our setup as of March 2020.
We are very happy with our selection of this Inverter. The 50 amp passthru made the installation much simpler than it would have been with a single side inverter. 2000 watts gives us about 16amps AC available, which is plenty for our needs (TV and Coffee). While 16A is enough to run an air conditioner, it drains the batteries very quickly. The nice thing is, everything is in place if we ever wanted to upgrade the batteries to more than 450Ah capacity and run that A/C longer.
Solar is the next big step, so stay tuned for that!
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