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Installing generator + inverter in a living quarter horse trailer.

Installing generator + inverter in a living quarter horse trailer.

Old 03-16-15, 11:28 PM
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Question Installing generator + inverter in a living quarter horse trailer.

I was tasked today with researching which generator to use in my dad's 2015 Bison Trail Hand trailer, which he will be living in for three years as he travels the country. In the process of scouring the internet, I found there was much I didn't know, and my dad knows far less than I. It was apparent that he may need to know much of the things I was finding. So, I learned as much as I could and am now too tired, but would like to be able to get back to him sometime tomorrow. I sent him an email of what I'd put together but feel like I may either be missing something crucial and/or overthinking it.
Here is the email I sent him. I'm not trying overcomplicate things for him, so understand that I did not divulge all details.

Ok, I'll try to keep this relatively simple. You currently have three dedicated power systems. First, a DC power system, supplied from the batteries. Any electronics that remain operable when the battery is the only source of power are run from this system. Your "shore" hookup, which powers outlets, A/C, microwave, etc. is supplied with AC power from the grid or a generator. The last is your propane system, which runs your furnace, water heater, and range. However, both the water heater and furnace receive their ignition sparks from a DC power circuit, meaning they will not operate without a charge from the battery. Conveniently, via a power converter, the DC batteries are charged when the shore power is connected.

Before I go any further, you should know some differences between DC and AC power. Firstly, AC currents cannot be directly stored in batteries, which important to know for a portable system. This is why most of your "need-it-now" systems are either battery and/or propane powered. AC is, however, required by most of today's sophisticated electronics because of its more versatile applications. This is why the rest of your system is designed to run on AC. Now, not all AC power is clean power. Grid power is generally acceptable quality and requires no further processing for most applications. And this is where generators come in.

Standard generators ($1000-1500 for 4400-5500 watt, full featured portables) produce a very raw form of AC energy. A combustion engine and an alternator are all they consist of. If you intend to power any computers, tv's, etc.. via generator when you have no access to shore power, some sort of additional processing is required. Power conditioners are simple and cheap but only correct a small fraction of problems which can cause damage to electronics. The only way to actually get appropriate power quality from a generator is to use a power inverter. There are two options: A. a pure sine inverter, which can be used with any AC electronics; or B. a modified sine inverter, which is not suitable for a bunch of commonly used electronics but cost roughly three times less. See: Best Inverter for an RV €“ Pure vs Modified and Watts. For the sake of explanation, I'll only refer to pure sine inverters.

A pure AC current can unfortunately only be created from a DC source though, which means that an AC power source will need to be converted to DC and finally inverted into a pure AC. An inverter setup is pretty simple but in the case of your trailer, there are a couple options to consider:

1. The raw AC generator current can run through a separate DC converter, into separate batteries, into an inverter and finally into your AC circuitry. This would require a transfer switch for changing between shore and generator power. Unless you want to run the shore power through the inverter also. In my opinion, processing grid power is not necessary and not worth the power losses from converting to DC and back. Though you would have the convenient option of doing so with a switch ($100?). The inverter would probably need to be rated at 1500 watt minimum ($150-500), 3000+ watt ($650-1200) if you want remove the chance of an overload.
2. The raw AC generator current can run through the existing converter and battery wiring, into an inverter which supplies the entire trailer with high quality AC power, including the existing DC system, which I'm pretty sure would require AC circuitry to replace the DC. This would mean the entire trailer would run off of best quality electricity, require no transfer switch, and it would all come from a single power source which only requires a generator when low (batteries), making operation very simple. Also, this does not require a very powerful generator, although it seems that only higher dollar generators include remote operation features. If you don't need remote operation and don't mind using less power while charging the batteries, you could put a small generator anywhere and carry it to the batteries when needed. The most feature rich option would be to get a permanent generator which has an auto-on mode when the batteries are low. You know how much those cost though. Also, a 4000 watt minimum inverter to handle the entire load is way expensive, new circuitry would be a pain, and there would be a permanent loss of around 10-30% power because of the conversion process and no option to use any DC power. This would place a huge load on the batteries which would need to be significantly upgraded as well. Definitely not the best option but it's there for your consideration.
3. Spend the extra dough on a generator with a built-in inverter ($2800-3300 for 3500-4500 watt rating). This would supply your current AC system with best quality power and you would not have to worry about finding an appropriate inverter and installing it, or batteries, or anything. Also, inverter generators are designed to be more fuel efficient/longer running, longer lasting, quieter, smaller, are available to plug sensitive electronics directly into, and waste less energy during conversion. Basically better in every way except the price.
4. Go budget performance with a power conditioner and slightly increase power quality, but run the risk of various AC electrical failures, and ultimately try to avoid using sensitive electronics altogether when off grid.
5. Do nothing and only ever use devices which can handle the power fluctuations from the generator. NOT recommended.
6. There may possibly already be an inverter installed, in which case I would suggest first confirming that it can handle the load of the generator and second, installing a transfer switch if there isn't one already. I couldn't find reference to one anywhere in the manual.

Options 1 & 3 are relatively the same price for parts, but the installation of option 1 could prove more expensive and may possibly void the warranty (talk to Bison). However, in option 3, the transfer switch option to run shore power through an inverter is not available unless you were to wire one in another converter, batter and inverter as well. Luckily that's not very important. Option 4 is cheapest if you are comfortable with not being able to work or use various other electronics when off the grid.

Note: If a portable generator is wired for it, and includes the appropriate automated systems, operation controls can all be wired directly into the cabin. The only thing I am unsure of is an automatic fuel line drain. I don't believe any portables do this, but it shouldn't be a problem. If you're not going to be moving, the generator can be turned on and off at your leisure. When you are ready to move, however, you should turn the generator off by cutting the fuel supply and letting it consume any fuel remaining in the fuel lines. Apparently, this must be done manually and would require you to climb the ladder. Sorry old man.

By the way, if you ever want to charge your truck batteries from the generator, carry a separate, cheap AC/DC battery charger as well.

I may have more to add but I'm tired and will check tomorrow.

Mmmmkay, lay it on me.

Last edited by Jewbacca1; 03-17-15 at 12:29 AM.
Old 03-16-15, 11:47 PM
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Welcome to the forums.

I don't like inverter system so I tend to shy away from them. I service motorhomes and they are a constant source of problems. They require a lot of battery power and battery maintenance. If you intend to spend a lot of time on the road.... they are one source of power to consider. With that form of A/C generation... your batteries need a lot of recharging.

3. Spend the extra dough on a generator with a built-in inverter ($2800-3300 for 3500-4500 watt rating). This would supply your current AC system with best quality power and you would not have to worry about finding an appropriate inverter and installing it,
That's what I would recommend. The inverter type of generators used in motorhome applications use variable speed engines based on load and are very quiet. I recommend a permanently installed unit that draws gas from the vehicles storage tank.

I looked and saw the unit you are describing. I'm guessing a permanently mounted generator will be an issue along with a gas supply.

What are your intentions for carrying the generator ? Just roll it out on wheels ?

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Old 03-17-15, 12:25 AM
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Oh, right! We ordered a hay rack with a ladder attached, which will fit as far back on the roof as possible. The generator will be bolted to the rack's frame and enclosed in a box of some sort to sheild from rain and road debri. It would be allright to have it up there right? Water could even leak in since it has an open space between the rack and the roof right? I was checking out hay lift systems but didnt like any/they were all too expensive. I did find a picture of exactly what I envisioned, but it isnt being manufactured. At the bottom of this page --> "Load-Up Power Bale Loader for Horse Trailers"
I can build that myself and it can be used to lift the generator as well.

I also plan to wire controls into the cabin which can be disconnected at the generator. I will use the 120 volt hookup just as it's designed to, and stow the cord when moving. I don't want to wire the generator permanently to the trailer.

Gas storage is a good question. Do you know of any sub $2000, compact, diesel inverter generators? If so I could store the tank uptop and not have to worry. With suitable protection, a gasoline tank could be put up there though, right? Except that's probably illegal now that I think about it. Maybe he'll just make due with the built in tank. He wont be running it every day, only when he's off grid. An auxilary gas tank can be put in the truck bed, which can fill a gas can which, he can then take up the ladder and refuel with.

Last edited by Jewbacca1; 03-17-15 at 12:43 AM.

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