Adding a inverter to our 2010 Bighorn 3055

I have seen some people running AC systems​ of the inverter. That's a large load and I'm thinking the microwave is as well. Your running the risk of battery overtemp. Also I believe your board that converts DC to 120 ac can be compromised.

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carl.swoyer said:

I have seen some people running AC systems​ of the inverter. That's a large load and I'm thinking the microwave is as well. Your running the risk of battery overtemp. Also I believe your board that converts DC to 120 ac can be compromised.

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The inverters have wattage ratings, and will shut off if they pull the batteries to too low of a voltage. Also, proper installation requires that a high amperage fuse be present on the 12 volt feed. I have a 125 amp fuse on the 12 volt feed to my 1500 watt inverter. My microwave is rated at 1100 watts, and I can run it off of the inverter. BTW, I have a Pure Sine Wave inverter. I have never tried to run my air conditioner off of the inverter, although it should have the run current, I don't imagine it could muster the compressor start current.

Carl,

We typically don't run the microwave for more than a couple of minutes at a time, usually to re-heat something. As to battery temp, I have never felt them get more than luke warm whether charging or drawing from them by using the inverter. The microwave is well within the rating of the inverter.

Bill,

I have a 300 amp DC catastrophe fuse in the positive side of the circuit right at the batteries.

carl.swoyer said:

I have seen some people running AC systems​ of the inverter. That's a large load and I'm thinking the microwave is as well. Your running the risk of battery overtemp. Also I believe your board that converts DC to 120 ac can be compromised.

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I have too. The Heartlander that I saw this in had a HUGE battery bank (Lifeline AGMs) and a roof of panels. It was quite the sight.

I think I have found a solution to installing the inverter. Today I talked to the dealer that sold me the inverter about how I can use a inverter to make both legs of 120 volts hot. It will involve reducing the amperage of the entire 5th wheel to 30 amps, which I think is a good tradeoff for the type of camping that we do.

The plan is to unhook one leg of the incoming power and cap it. Then tie both legs together in the breaker box. That way when the trailer is plugged into a 50 amp pedestal one leg will be dead coming into the trailer. Basically run one leg of the 50 amp into the inverter and run the output of the inverter to the input of the breaker box.

Does anyone see a problem with this setup? We only have one air conditioner and are used to only running heavy loads like microwave and vacuum cleaner by themselves.

Thanks,
Brian

I don't understand why you would want to move down from 50amp to 30amp service...???

Big-B said:

. Basically run one leg of the 50 amp into the inverter and run the output of the inverter to the input of the breaker box.

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IMHO...I don't think your dealer really understands how to wire the inverter, let only a 50amp service correctly. You don't wire AC power to an inverter....the inverter creates AC power from the battery/batteries. You need a transfer switch to do this correctly. Jesstalk'n gave a good drawing of this, and I've attached my layout as well.

Do you have an inverter that can provide 50amp?

Here is how I have planned my inverter build out. I have all the parts...just waiting for the weather to get better so I can have a few days to get this done.

Big-B said:

Basically run one leg of the 50 amp into the inverter and run the output of the inverter to the input of the breaker box.

Does anyone see a problem with this setup?

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As mentioned above.....if someone suggested to run one leg of 120 to the input of an inverter, I would suggest running from them....that wouldn't be a pretty sight when the power get turned on.

Big-B said:

I think I have found a solution to installing the inverter. Today I talked to the dealer that sold me the inverter about how I can use a inverter to make both legs of 120 volts hot. It will involve reducing the amperage of the entire 5th wheel to 30 amps, which I think is a good tradeoff for the type of camping that we do.

The plan is to unhook one leg of the incoming power and cap it. Then tie both legs together in the breaker box. That way when the trailer is plugged into a 50 amp pedestal one leg will be dead coming into the trailer. Basically run one leg of the 50 amp into the inverter and run the output of the inverter to the input of the breaker box.

Does anyone see a problem with this setup? We only have one air conditioner and are used to only running heavy loads like microwave and vacuum cleaner by themselves.

Thanks,
Brian

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Brian,

I looked back briefly at your first post. If I understand, you have a gas generator that outputs 120V AC, a wind generator that outputs 12V DC, and solar panels that output 12V DC. You only use a gallon of gas per week in the gas generator, which suggests very little run time.

You didn't mention the model of your Magnum inverter, but it sounds like an MS2812 which has both 120V AC and 12V DC inputs, an automatic transfer switch built in, along with a built in power converter to charge the batteries when on shore power.

The Magnum manual illustrates a number of ways to install the MS2812, all of which involve adding a sub-panel. The main circuit breaker panel provides shore power to the MS2812 input and the loads that you want to use on battery power get moved to the sub-panel, which is powered by the MS2812 when on battery power.

What you're proposing to do is to downgrade your electrical system from 50 amp to 30 amp to avoid installing a sub-panel.

Given that the future is unpredictable, and you don't really know when you might be back on the grid, a sub-panel seems to me to be a better approach. The MS2812 manual has a number of illustrations showing how to set that up.

I believe that the ms2812 required a 120 in to allow the transfer switch to toggle between shore power and dry camp. When the inverter senses a change in shore power or absence of it will automatically switch over to the alternative source of power. Without the 120 in the Magnum Inverter can't toggle between shore power and batteries

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Sorry about the delay replying. We had company for a few days and the inverter and charge controller just sat in the basement.

Oregon Camper: I don't really want to downgrade from 50 amp to 30 amp because my inverter has a transfer switch that is only rated for 30 amps. This 5th wheel is similar to our last one as far as how much power it needs to sustain our lifestyle and I figure it can work. But given a choice I would prefer the 50 amp. Also, as to having 120 volt come into the inverter, that is because the inverter has a built in transfer switch so the 120 goes in and out. The transfer switch automatically switches over to inverter power if you lose shore power. We don't have a built in generator so we just plug the main power cord into the generator instead of shore power.

I am interested in the setup that you show with a stand alone transfer switch that can handle both legs of a 50 amp service. It looks like they tie both legs together when the inverter is supplying power and it automatically separates the two legs when you plug into shore power. Is that how you understand it to work?

LBR: As I explained above, the reason the 120 is run into the inverter is because the inverter has a built in transfer switch.

Dan Mayer: You are correct about the inverter. It is a Magnum ms2812. I will take a look at the manual and see if they explain how I can install it without a sub panel, I'm all for it. The idea of a sub panel and having to pick and choose which circuits will work is something I would dread compared to downgrading to 30 amp. About the only reason I can see for needing 50 amp would be if we added another A/C and I don't plan on that.
What I am wondering about is if I could use a 50 amp transfer switch instead of the one in the inverter. It would probably mean getting a different inverter without the built in transfer switch but they are usually less money too, so it offsets the transfer switch costs.

I have read a lot about the whole inverter/transfer switch/charger thing over he last 10 years or so and also installed the Xantrex in our last rv. One line of thinking among some who were designing systems was to have separate components, so if one fails you aren't totally out of service.

Carl: You are correct about the 120 coming into the inverter, it feeds the transfer switch.

Thanks again for all the replies. I should be a little more prompt about answering posts now that the company is gone. If anyone has any more input as to using a 50 amp transfer switch to keep both legs of the incoming shore power but allowing for a single leg input from the inverter, I would like to hear about it.

With my MS2812 and it's​ pass thru technology I chose two circuits. One for the bathroom and bedroom and the other for kitchen and TV. This works very nice for us during dry camping. So I took the wires out of the distribution panel and spliced them together to the line out on the MS2812 . I still have a small sub panel for the inverter.

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I think you are back feeding. If you did this get a meter and carefully check the shore power cord prongs for ac with the inverter off then on.

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No backfeeding. 120 and 12 volts going into inverter and 120 coming out. Transfer switch won't let that happen.

Update:

I took a look at the different diagrams in the Magnum manual after seeing that the inverter 120 volt connections showed L1, L2 and common. Then just to be sure I wasn't missing anything I called Magnum and talked to their tech. support people. The guy assured me that the MS2812 inverter will indeed pass both lines through the inverter transfer switch and also power both lines with the inverter. One thing that they did warn me about is the fact that the inverter transfer switch is only rated at 30 amps. I installed a double 30 amp breaker before the inverter to make sure that it can't overload the transfer switch.

One other tip that I would like to pass along is something that I picked up from a guy here on the ranch who has done a lot of inverter/solar work. I had told him that I wanted to mount the inverter on the wall between the basement and the front compartment but didn't know if the OSB board would handle the weight. My plan was to reinforce it with a couple of pieces of angle iron in the front compartment. He told me that what he had done several times was to mount all of the components on a separate piece of plywood then mount the whole thing to the wall. That is what I did and it was a lot easier to mount all of the components and wire them up with it all on a bench instead of in the basement.

This setup will derate the 50 amp service from two lines of 50 amp to two lines of 30 amp each. I decided on this route as opposed to wiring a sub panel because I want to have everything in the trailer powered up instead of only certain circuits.

My install is almost complete and I am looking forward to trying it out in the next couple of days.

Big-B said:

Update:

I took a look at the different diagrams in the Magnum manual after seeing that the inverter 120 volt connections showed L1, L2 and common. Then just to be sure I wasn't missing anything I called Magnum and talked to their tech. support people. The guy assured me that the MS2812 inverter will indeed pass both lines through the inverter transfer switch and also power both lines with the inverter. One thing that they did warn me about is the fact that the inverter transfer switch is only rated at 30 amps. I installed a double 30 amp breaker before the inverter to make sure that it can't overload the transfer switch.

One other tip that I would like to pass along is something that I picked up from a guy here on the ranch who has done a lot of inverter/solar work. I had told him that I wanted to mount the inverter on the wall between the basement and the front compartment but didn't know if the OSB board would handle the weight. My plan was to reinforce it with a couple of pieces of angle iron in the front compartment. He told me that what he had done several times was to mount all of the components on a separate piece of plywood then mount the whole thing to the wall. That is what I did and it was a lot easier to mount all of the components and wire them up with it all on a bench instead of in the basement.

This setup will derate the 50 amp service from two lines of 50 amp to two lines of 30 amp each. I decided on this route as opposed to wiring a sub panel because I want to have everything in the trailer powered up instead of only certain circuits.

My install is almost complete and I am looking forward to trying it out in the next couple of days.

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Thanx for the update....this is basically the same direction I will be going...solar/full house inverter system...when my time comes. The 2800 to 3000 pure sine will be on my list, just haven't decided on brand yet....following you closely...lol

I put power to the new inverter yesterday and it works like a charm. It should be a nice upgrade compared to the 1.750 watt inverter that we have been using. For the last 3 months we have had the whole rig plugged into the inverter with a 15 amp adapter to the shore power cord. You learn how to conserve power when that is all the power you have.

About all that I have to do yet is mount the remote display. Right now it is sitting in the basement with the inverter. I will try to post some pictures later.

Earlier this week I added two more Trojan T-105 batteries bringing the total to six. The idea is that when we have lots of clouds or little wind the extra capacity will come in handy. Here are a couple of pics of the completed install. The battery pic is before I had the wiring all hooked up. With all four panels hooked up I am getting 4Kw a day with full sun. That is more than we typically use. About the only thing electric that we don't run is the air conditioner. The inverter passes both legs of 120 volts through at 30 amps which means the electric system has been reduced from 100 amps total to 60 amps. Still enough to run anything we want to run.

Big-B said:

Earlier this week I added two more Trojan T-105 batteries bringing the total to six. The idea is that when we have lots of clouds or little wind the extra capacity will come in handy. Here are a couple of pics of the completed install. The battery pic is before I had the wiring all hooked up. With all four panels hooked up I am getting 4Kw a day with full sun. That is more than we typically use. About the only thing electric that we don't run is the air conditioner. The inverter passes both legs of 120 volts through at 30 amps which means the electric system has been reduced from 100 amps total to 60 amps. Still enough to run anything we want to run.

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In the 2nd photo, I see what looks like a propane gas line regulator on the left side. Tell me I am wrong about this.

Very nice set up.


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wdk450 said:

In the 2nd photo, I see what looks like a propane gas line regulator on the left side. Tell me I am wrong about this.

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Looks to be his BBQ stored in the bay, I think?