Building the tongue mount frame for HVAC and electrical

I first had to weld some risers to clear the electric brake box and other wiring on the tongue.  On the bottom of the risers is 2" plate pieces for U-Bolts which will hold the whole assembly down on the tongue.

Here is the welded box assembly which was then welded to the risers.

The completed tongue assembly

Turned over for painting.

The HVAC compressor mounted.

Ready to install on the tongue!

Mounting the HVAC and electrical system on the tongue

After welding and painting the frame for the tongue, I mounted the HVAC unit. 

Then set it on the tongue.

Then added the batteries (in battery boxes) and the inverter assembly is mounted in the plastic toolbox on top of the frame.

The whole unit is bolted to the tongue with heavy U-bolts.

Battery and Inverter Installation

The two batteries mentioned in the previous post were mounted on the tongue and wired in parallel with AWG 1/0 welding cable.  The inverter is wired with a 500 amp fuse between the battery bank and the inverter, and I added a master shutoff switch between the battery bank and inverter.  On the 110V AC side, the HVAC was wired into the primary output and is the only thing on that circuit.  The cooking and electricity in the trailer is all run from a separate GFI protected plug.

I then dropped the whole assembly into a plastic toolbox made for the back of a pickup.  This assembly is mounted on the tongue above the HVAC unit.

Youtube Video Now Live

Finally got around to making a video of the completed trailer.  See it here.

Back From Winter "Shutdown" and All Electric RV Update

Had to shut down work on the trailer because of too much work and too much winter.  I did do a week-long test run of the battery system in October with the batteries not permanently mounted to see if my inverter and battery setup worked as expected, and it did.  I slept in the trailer, heated water, ran the microwave, even plugged in a small ceramic heater to take the chill off a couple of cold mornings, and it worked perfectly.

Next step is to build the battery system permanent mount for the tongue, then install the mini-split heat pump and finish it off.  More blog posts coming on that, but I wanted to pass along an article that makes me think more than ever that the all-electric RV is coming and soon!

Tesla Powerwall for All-Electric RV?

As I've built my project, I've been planning carefully to maximize my system based on 2 large deep-cycle conventional marine batteries.  Its working, but its heavy and limited.   Now Tesla has announced their new Powerwall and I am totally jazzed - this is the direction that battery technology is going and I could easily see how this could be in the all-electric RV of the future.  Read up on it and I'll be doing more research on the Powerwall and comparing it to my current battery setup in future blogs.  

Ok, Lets Talk About Toilets

This is nobody's favorite topic, but we need to plan for our toilet facilities.  A pet peeve of mine is the conventional RV Flush Toilet that makes no sense to me except that the manufacturers wanted to make it seem like you're in your home bathroom.  For any kind of self-contained camping,  it doesn't make sense to carry the extra gallons and weight in fresh water, and store gallons of black water you flushed in another tank.  Heck, we're trying to get our toilets at home to use less water so why are we doing this with our campers?!  I'm convinced the RV of the Future is going to leverage either composting toilet technology or ultra low volume cassette-type toilets to save water, weight, and hassle.

Cassette Toilets

You're starting to see more RV's go to a cassette-type system where the toilet and holding tank are one connected system. They use little water and the holding tank has wheels and a retractable handle so you just pop it out and dump it in a toilet or dump station.




Thetford makes the most popular ones and you often see these combined with a shower enclosure for very effective RV space utilization.

Composting Toilets
The off-grid movements started using composting toilets over 20 years ago and they have gotten progressively better and more popular. They are a self-contained toilet that works by evaporating liquids and composting solids. You don't need water, city sewer hookups, or a septic system. They're great for vacation homes and any water conservation application.  Sun-Mar are one of the original and most popular manufacturers.

Unfortunately these haven't been produced in a size and price range that was good for RV's though, until recently. Now there's a composting toilet design for marine use manufactured by Natures' Head that I think would be ideal for an RV.




The GearBox Toilet Choice
As I was designing my trailer I got carried away and I had a bathroom in it at one time.  When I scale it back to the current size, I really didn't have room for a separate bathroom.  If I was going to put in a bathroom, the marine composting toilet is very intriguing.  But in the end I'd probably go with the cassette toilet and combine it with a shower in the same space.  

For the GearBox, I'm going simple and space efficient, so I went with Thetford's Curve which is a higher end portable toilet.



These are a big step up from the tiny, square porta-potties, and its easy to separate the tank and dump in my home toilet. Amazon to the rescue again. 

Inverters

Because of the growth of solar and other alternative energy solutions, there's been a lot of innovation in the DC power to 120V AC inverter industry.  I wanted a combo inverter / charger which converts 12V DC into 120V AC when you're travelling and not plugged in, and when plugged in to normal household current, it will convert 120V AC to 12V DC and charge the battery system. These modern electronically controlled inverters automatically sense if you're plugged in or not and will transfer over nearly instantly.  And they protect your battery bank with over / under voltage sensing 

Pure vs. Modified Sine

You will come across "Pure" versus "Modified" sine wave inverters when shopping.  Modified sine wave inverters have gotten much better in recent years and they cost quite a bit less, but one of the reasons they cost less is that they are not quite a perfect sine wave AC cycle like you would have with household current.  For some applications this is just fine, but for sensitive electronics and other types of applications they are not.  In applications where modified sine wave inverters are not suited for, they heat up and certain electronics don't function.  When I hear heat and functional problems, I hear inefficiency and from my dreaming about amps post that is the last thing I want.  So I narrowed my search to pure sine wave inverters.

There's quite a range of prices in the pure sine wave inverter field.  The best ones with the highest efficiency in the 2-3K Watt size were anywhere from $1200-$2400.   You can find very cheap ones on eBay for $500 but I would stay clear of those like the plague.   Do your research and I found both the Inverter Store and Inverters R Us to be good dealers who responded well to support and sales questions. 

As I was estimating my appliance power draw, unless I turn everything on it once at full blast, I really should be able to get by with a 2000 W inverter.  But that leaves little margin, I also happened to find a good deal on a 3000 W inverter with solar charge controller on eBay, in case I want to add solar panels later.  In talking with dealers I came across the Aims brand which seemed to be a decent compromise on quality and affordability, and is an established brand.  My GearBox inverter is an Aims 3000 Watt Low Frequency Pure Sine Solar Inverter Charger.  Amazon also has a similar one without the Solar Controller.