Has anyone hardwire in an inverter?

[RVGeek]

I’ve installed a 750 watt, modified sine wave inverter on a 2015 23U which has two 90Ah, 12V batteries (90Ah useful capacity, observing the 50 percent discharge rule). The device was from the Candy Store (i.e., Harbor Freight Tools), costing about $45. It’s mounted on the wall, just forward of the side entry. It uses the 3’ supplied cables and is connected directly to the batteries, located beneath the entry steps. An 80-amp fusible link (from auto parts store) is installed inline at the positive battery post to protect the circuit.

When switched off, the inverter presents a negligible parasitic drain (less than 10 mA). It’s used to power a small 600 Watt coffee maker, hand vacuum, etc. I’ve also installed a second, 60 watt inverter to power the TV and have placed a switch in the DC circuit, as the TV will present a small drain on the batteries even when switched off. The smaller inverter is much more efficient for the lighter TV load.

It’s prudent to monitor battery voltage and to not permit the quiescent voltage to drop below 12.1 volts (50 percent charge). An inexpensive, two-wire digital panel voltmeter allows monitoring the batteries. These are available on eBay for less than $5; one with round mounting hole is easier to install.

Originally Posted by Drkevr

Our 2017 freedom elite 26HE only has a converter charger and we would like to also be able to do some dry camping without always having to run the generator. I doubled up my house batteries to now have two 100ah batteries in parallel to work with but would like to simply add an inverter for now. Thinking of upgrading my converter to an inverter Charger when we do solar upgrade but that is a couple years off.

[Wiley1]

I have a Thor Freedom Elite 23H. This model has a dinette and a "barrel" chair. This is my first motorhome and I was disappointed to learn that not all RV's are equipped with an inverter from the factory. Why not?

I did NOT want an inverter that only powered a few outlets. I wanted a WHOLE HOUSE inverter. I'm an electrician, but I didn't really need any electrical skills to solve this issue.

Here is what I did:
1. Expanded the under-stairs battery mounting bracket to hold 4 batteries instead of only 2. There was plenty of room under there. Thor should make this standard on all models.
2. Installed (4) 200ah AGM batteries for a total of 800ah.
3. Installed a State of Charge meter so I could see the exact charge level of the battery bank. I recommend one of these to anybody with batteries, with or without an inverter. It allows you to measure exactly how much DC power is being used and how long it might last.
4. Installed a low-frequency 2500va true-sine inverter/charger under the seat of the dinette, with a wired remote control panel. The model I used has a 30A integrated transfer switch, so I am no longer using the transfer switch or charger that came with the coach. This gives me more than 20A (60A surge) of continuous power to the breaker panel. Any outlet or on-board device is now powered, both 12vdc and 120ac, but not for long.
5. Just to be sure I wouldn't cook my inverter or burn up my MH, I installed a thermostat-controlled fan under the dinette seat with an alarm and a remote sensor taped to the inverter housing. Any time the temp of the inverter case exceeds 120 degrees F, the fan powers on to ventilate that space.

What I love about this setup:
1. The best benefit is being able to tool down the road while running the fridge on AC. This keeps our food cold and our ice cream doesn't melt. The charging current from the vehicle alternator is almost enough to keep the fridge running, so there is only a small drain on the batteries. I know because I can see the current draw in both directions using the SoC meter. The propane valve is usually shut off when we are moving. it just seems safer and many tunnels require propane to be shut off before entering.
2. To get maximum longevity from AGM batteries, they should not be discharged below 50%. We break this rule occasionally but, in general, we have the SoC alarm set to 50% and we pay attention to it. That gives us 400ah of usable power before we need to charge batteries.
3. Laptops. Phones can be charged from any USB port, but most laptops need 19vdc to charge. The best way to get that is by connecting the 120vac charger that comes with the computer.
4. Microwave oven. No, you can't roast a turkey. But, you can heat up a cup of coffee, melt some cheese, or pop some corn while you're driving down the road.
5. TV. For some dumb reason, most TV's in motorhomes run on 120vac. Now my passengers can watch TV without shore power. We have even let the TV run all night using inverter power.
6. Appliances. Toasters, coffee pots, can openers, vacuum cleaners, etc. Anything will work but not all at once and not for long. Watch the SoC meter and perhaps wait until you're on shore power to run that hair dryer.
7. Stopping. When we stop for gas or food, we don't change anything. The engine stops, the alternator charging stops, but the fridge keeps running on battery power. Again, not for long, maybe an hour. Beyond that, you will want to run the fridge on propane.
8. We don't need to think much. When the green light is on, the coach is running on generator or shore power. Anything can be powered up for as long as needed. When the yellow light is on, we are on battery/inverter power, and we need to be more conservative with how we use power. If the SoC meter beeps, the battery bank is half-way depleted and we need to find a new source of power soon. Easy. No breakers to keep track of. No switches to throw. No plugs to connect. No unpowered outlets.

Remember, it isn't just the Amps, and it isn't just the Hours. It's the AH (amp-hours) that deplete your batteries. You can run the low power stuff for long periods, but the high power stuff can only run in short bursts.

Do we have a generator? Yes, the Onan 4000w that came with the rig -- big enough to run everything and charge our batteries, all at the same time. But we haven't used it since we installed our inverter, except for testing and maintenance. No fuel used, no stink, and no noise. The people at Cracker Barrel do appreciate.

What we don't like:
1. No Air Conditioning. Don't even think about running the AC on inverter power. It will work for about 12 minutes, then your batteries will be dead and slightly damaged. Instead, get a couple of (AC or DC) fans or (gag!) fire up that noisy generator.
2. My inverter model must be powered up in order to pass shore power through the transfer switch. That makes no sense to me, but that is how it was designed. Annoying, but not a big deal.

Future plans:
Right now, we have only three ways to charge our batteries: shore power, vehicle alternator, and generator Solar panels would add a fourth method. On a sunny day, 2-4 panels might provide enough power to travel long distances without switching the fridge to propane.
I suppose we could add more batteries, but where to put them?

I have tons more to say on this subject. Please respond here or PM me with questions. I can give you the make and model numbers of anything I've installed. I even have a spreadsheet of all my appliances and how much real-life measured power each one uses.

[RVGeek]

Impressive setup.

I assume you installed four 12V AGMs because checking electrolyte levels might be an issue with the expanded battery tray. The new batteries are most likely 4D-series batteries (to achieve 800Ah total capacity at 12V). If so, the total battery weight would be approximately 500 lbs, compared to the 120 lbs of the original 27s. These would require a battery tray nearly four times the original size and a lot of extra reinforcement. (4Ds have a foot print slightly smaller than two 27s.) My 23U doesn’t have the room to expand the battery tray nearly that much. I’m curious where you put them.

Also, I’m not sure what a low-frequency inverter refers to. All RV inverters in North America operate at the same frequency, nominally 60 Hz.

[Wiley1]

Originally Posted by RVGeek

Impressive setup.

I assume you installed four 12V AGMs because checking electrolyte levels might be an issue with the expanded battery tray. The new batteries are most likely 4D-series batteries (to achieve 800Ah total capacity at 12V). If so, the total battery weight would be approximately 500 lbs, compared to the 120 lbs of the original 27s. These would require a battery tray nearly four times the original size and a lot of extra reinforcement. (4Ds have a foot print slightly smaller than two 27s.) My 23U doesn’t have the room to expand the battery tray nearly that much. I’m curious where you put them.

Also, I’m not sure what a low-frequency inverter refers to. All RV inverters in North America operate at the same frequency, nominally 60 Hz.

First of all, I must apologize and admit to being a idiot, or maybe just an old man who suffers the occasional brain fart.

My four AGM batteries are actually 100ah each for a total of 400ah, with only 200ah usable in practicality. I bought them from Windy Nation. AGM was a great choice because they are affordable and maintenance free. Tuck 'em away, don't abuse them, and forget about them for a long time. The size and shape are almost identical to the #27 that I yanked out. After these die, and I win the Lottery, I might consider Lithium.

The existing battery tray allowed two #27 batteries, end to end, one of which would not be fully accessible because of being partially tucked under the stair housing. We went under the vehicle and removed the lip on the back of the tray floor then doubled area of the tray floor where the batteries rest. Then we reinforced the sides and painted everything black There was a lot of cutting and welding involved.

The "inside" two batteries have to be dropped in first and slid under the floor with the cables already attached. Then the two "outside" batteries can be dropped in and cabled. Now I have 1.7 accessible batteries, and 2.3 inaccessible batteries.

When you get into the research on inverters, you find two types: low frequency and high frequency. This has nothing to do with the 60 Hz output.
It is all about the circuitry that generates the waveforms inside the box. A low frequency inverter has much larger transformers, costs more, and has fewer failures. It might have a higher idle current draw. The box is significantly larger and heavier than a high freq device. I was tempted to get an HF inverter to save $$ and space and heat and weight but, in the end, I went for the more reliable design because of all the vibration in a Class-C truck frame, especially in an E450. It was a tight fit under the dinette seat. We had to a design a little table to hold it above the plywood floor.

Here is the one I bought, but I found it on Amazon for less:
https://theinverterstore.com/product...waAncFEALw_wcB

If anybody is interested, I can post some pictures.

[ksrow]

I would love to see some pictures of your battery expansion. Thanks

[Wiley1]

Originally Posted by ksrow

I would love to see some pictures of your battery expansion. Thanks

Here is a pic with my step open and a diagram for how to wire the batteries. Notice that the diagram is upside-down compared to my picture.

You can't see much from this angle. It looks exactly like two #27 batteries with top posts and lots of really fat cables. Actually, there are four AGM batteries under there, two outboard and two inboard. Even if you squint, you can't see the other two batteries under the deck.

If I ever get this rig up in the air, I'll take some pictures from underneath, but those won't be all that remarkable either. Just a double-wide iron battery tray, painted black. I don't even tie down the four batteries because they have no place to go. They are surrounded on all six sides when the step is closed.

I used 00-ga (2/0) to tie the batteries together and for the run to the inverter, which are two sizes larger than the chart calls for. I like to overbuild a little so I don't have to worry about voltage drops or cables getting warm from high current. A little more difficult to work with, but safer and better performing.

https://www.wiringproducts.com/battery-cable

[taylorbob1]

Originally Posted by Wiley1

Here is a pic with my step open and a diagram for how to wire the batteries. Notice that the diagram is upside-down compared to my picture.

You can't see much from this angle. It looks exactly like two #27 batteries with top posts and lots of really fat cables. Actually, there are four AGM batteries under there, two outboard and two inboard. Even if you squint, you can't see the other two batteries under the deck.

If I ever get this rig up in the air, I'll take some pictures from underneath, but those won't be all that remarkable either. Just a double-wide iron battery tray, painted black. I don't even tie down the four batteries because they have no place to go. They are surrounded on all six sides when the step is closed.

I used 00-ga (2/0) to tie the batteries together and for the run to the inverter, which are two sizes larger than the chart calls for. I like to overbuild a little so I don't have to worry about voltage drops or cables getting warm from high current. A little more difficult to work with, but safer and better performing.

https://www.wiringproducts.com/battery-cable

I love what you have done.
I know that I speak for all Vegas/Axis E350/450 owners when I say “great job!”
Now we all want to see how you fabricated the battery tray to add the two additional batteries.
My space is limited to running 3 batteries side to side, front to back (did I describe that correctly?)
That is, there’s not enough width to place two additional batteries in your configuration on my rig.

[Mo_Mike]

Originally Posted by taylorbob1

Many on this Forum have hardwired after-market inverters into their rigs.
The following link is very helpful, which is part three of 3 videos.
This video includes a wiring diagram from the WFCO Converter to the inverter to the outlets.
The inverter controls the non-GCFI outlet line (TV outlets, 3 way Fridge, other interior outlets)...


https://youtu.be/sSb6vC6orzM


As previously discussed, you must have an Auto-Transfer-Switch either incorporated into the inverter or as a separate unit within the inverter line.

The AIMS inverter discussed in this video is still available on-line but at a much higher price. You’ll also want to install the $30 remote. Here it is on Amazon...

https://smile.amazon.com/AIMS-POWER-.../dp/B074CL21FS

This is what we installed. Works GREAT and allows us to run the refrigerator on electricity when driving (instead of gas) allowing the alternator to charge the batteries. And, providing charging power for laptops.

[Wiley1]

Originally Posted by taylorbob1

I love what you have done.
I know that I speak for all Vegas/Axis E350/450 owners when I say “great job!”
Now we all want to see how you fabricated the battery tray to add the two additional batteries.
My space is limited to running 3 batteries side to side, front to back (did I describe that correctly?)
That is, there’s not enough width to place two additional batteries in your configuration on my rig.

When I got my 2017 Freedom Elite 23H, I noticed there was barely enough room on the stock battery tray to hold two #27 batteries, end to end. In the picture, you can see the left (rear) battery is partly tucked under the stair housing.

When I crawled under the rig, I saw there was a huge void between the battery tray and the drive shaft. We were able to remove the lip on the inboard side of the battery tray and weld another steel plate to effectively double the surface area of the battery tray. We also added some reinforcement in the front, back, and side to support the extra weight. Now the two inboard batteries can (must) be slid under the deck, to allow the two outboard batteries to drop in.

I've never seen underneath a Vegas/Axis. What is stopping you from doing the same thing I did? Certainly, the width of your E350 is the same as my E450 and the drive shaft runs down the center. What is interfering? An exhaust pipe? A catalytic converter? A muffler?

The batteries I'm using are BAT-ML12-100: 12.9" x 6.8" x 8.7"
To get a pair in there, side by side, the battery tray needs to about 13.8" wide including wiggle-room.
If the space is too small, you might be able to fit a bank of BAT-ML12-080: 10.2" x 6.6" x 8.3" For those, the tray would only have to be about 13.4"
But, as the model number suggests, they are only 80ah each.

[Wiley1]

Originally Posted by Mo_Mike

This is what we installed. Works GREAT and allows us to run the refrigerator on electricity when driving (instead of gas) allowing the alternator to charge the batteries.

Yep. But, for me, trying to power one set of outlets on shore/generator power and another set of outlets on inverter power was just too much trouble. I decided to buy the biggest baddest inverter that would fit under the seat of the dinette, which turned out to be an AIMS low-frequency 2500W.

Now, EVERY outlet and EVERY appliance in the rig is powered by the inverter.
We just have to remind people not to turn on the AC when the little yellow light is on because the batteries will be kah-put in short order.

[the_alpine]

Hey Wiley - any chance you have a wiring diagram of your setup? I’m wanting to do the exact same, but I have no accurate wiring diagram to start from.

[Wiley1]

Originally Posted by the_alpine

Hey Wiley - any chance you have a wiring diagram of your setup? I’m wanting to do the exact same, but I have no accurate wiring diagram to start from.

I didn't draw a wiring diagram because the electrical part of the job was really simple. The toughest part was getting that gigantic box to fit under the dinette seat.

The AIMScorp unit that I bought is a combination inverter and charger.
Here are the basic steps:
> locate the #10 (30A) cable from the ATS (automatic transfer switch). disconnect it from your AC breaker panel, and connect it instead to the AC input side of the inverter.
> connect the AC output of the inverter to the AC breaker panel
> locate the breaker that was used to power the stock converter, flip it off, and put a piece of tape on it. Unless you have a massive battery bank, you won't need it anymore.
> connect the DC input of the inverter to your battery bank with the fattest cable you can reasonably work with. This cable will carry a lot of current so, the shorter, the better.
> unless your inverter is easily accessible, you will want to buy the remote control panel. I put mine just inside the exit door next to my SoC meter and ran the control cable through the floor and under the chassis.

We can talk about SoC and battery management in another post.

That's it. Any questions?

[robtwebb]

Originally Posted by Drkevr

Thanks, was able to order an AIMS 2000 watt with remote. Should be in by Tuesday so I can wire in next week.

I have a 2018 Freedom Elite 26HE. I found the solar input on the roof and I am going to install 2 Renogy 100w panels, renogy charge controller and AIMS 2500w inverter. Any advice? Still trying to figure out where the inverter will go.

[robtwebb]

Originally Posted by Wiley1

I didn't draw a wiring diagram because the electrical part of the job was really simple. The toughest part was getting that gigantic box to fit under the dinette seat.

The AIMScorp unit that I bought is a combination inverter and charger.
Here are the basic steps:
> locate the #10 (30A) cable from the ATS (automatic transfer switch). disconnect it from your AC breaker panel, and connect it instead to the AC input side of the inverter.
> connect the AC output of the inverter to the AC breaker panel
> locate the breaker that was used to power the stock converter, flip it off, and put a piece of tape on it. Unless you have a massive battery bank, you won't need it anymore.
> connect the DC input of the inverter to your battery bank with the fattest cable you can reasonably work with. This cable will carry a lot of current so, the shorter, the better.
> unless your inverter is easily accessible, you will want to buy the remote control panel. I put mine just inside the exit door next to my SoC meter and ran the control cable through the floor and under the chassis.

We can talk about SoC and battery management in another post.

That's it. Any questions?

I just saw your post about inverter/charger. You say connect the “DC input to the batteries”. My question is doesn’t the DC input on the inverter also serve as an output when the inverter is charging the batteries?

[16ACE27]

Originally Posted by robtwebb

I just saw your post about inverter/charger. You say connect the “DC input to the batteries”. My question is doesn’t the DC input on the inverter also serve as an output when the inverter is charging the batteries?

Depends on whether it's a simple aftermarket inverter;
or an expensive inverter/charger.

Most inverters do not charge the batteries.

[robtwebb]

Originally Posted by 16ACE27

Depends on whether it's a simple aftermarket inverter;
or an expensive inverter/charger.

Most inverters do not charge the batteries.

It is an AIMS 2500w inverter / charger. Similar to what you have.

[16ACE27]

Originally Posted by robtwebb

It is an AIMS 2500w inverter / charger. Similar to what you have.

This one?


AIMS PICOGLF25W12V120AL

[JimC]

Originally Posted by gte534j

Thanks for the diagram- thats really helpful to see.
I just got a cigarette type inverter that i can plug into the dash board to keep it simple when i want to run small AC devices.

How do you physically plug into your DC/AC converter if its mounted under your sink? Did you wire in a outlet or just make a extension cord?
Also- did you upgrade your batteries to AGM?

The AC side of the inverter is done with 14/2 w ground romex to 4 separate outlets in strategic locations around the camper [ dinette, TV/dish/DVD control area, adjacent to bed, near stove [not wet area] ]. My outlets for the inverter use white plugs/plates while the shore/gen outlets are brown. The model inverter I had has four circuit connections. Some wires I fished to locations. One circuit to the dinette was routed under the coach floor in protective flexible conduit. The on/off switch w/battery monitor is remotely located at the entry stairway near controls for the solar, Bigfoot levelers, and DC disconnect switch. By having one of the outlets in the AV cabinet, we are able to have TV/DVD/DVR viewing whlie traveling, for those rearward of the driver. If you wished to have more outlets, discretely placed junction boxes could be used to wire them. The hardest part is fishing the wires. I don't like extension cords although they could be used.
The most important issue in the installation is to use adequate wire size from the batteries to the inverter. You asked about battery types: I have two flooded lead acid batteries which I regularly check the fluid levels on. When I need to replace them I will go to AGM for less maintence.
I have cold weather boondocked several times. I have never run out of power. If your batteries started running low you could just start the vehicle engine or the generator for 15 minutes to recharge the batteries at night.
Hope this helps.
Jim C.

[robtwebb]

Thanks. I am doing it differently from your setup. I am going to have the inverter power my AC panel so I don’t have to run separate wires as you have described.

[robtwebb]

Yes.