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Old 11-22-2017, 12:17 AM   #1
LifeByDesign
 
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Default OFF GRID battery powered AC/Heat. Fully functional.

OFF GRID AC & HEAT. Is it possible?? The short answer is YES it is very possible. The complicated answer is that it takes work and a specific design to pull it off. What will follow is my attempt to document what work was done through a series of attached photos and description but if you are impatient you can cut to the chase and view all photos on our IG @ourlibertyvan account. This will be my attempt in getting the information consolidated in one space. The challenge was simple, design a system that allowed off grid heat and cooling operating on battery power completely and have it all fit into a nice package installed in our 2016 170 3500 4x4. Sounds simple but unfortunately nobody is doing it so I didn’t have anyone to copy. First challenge is selecting a unit that will fit our needs. We needed something that could deliver climate control from freezing temps to super uncomfortable humid heat. Regular RV systems fail in this regard because they can only handle heating operations from 40F and above and the efficiency of the AC system is poor. I also didn’t want to incur the expense of having two separate systems (ie: propane or diesel heat) plus a separate AC system. That left me with an option to go with a residential heat pump system. What I found was the super efficient systems operated on split phase 240VAC. (1st large challenge as most RV electrical systems will produce 120VAC). What was designed was an electrical system with battery storage of 10.6kw, produced 4000w of inverted power and could operate a Fujitsu 9kbtu Halycon heat pump assembly that can produce heat all the way down to -5F and also produce AC. This is the 33.3 SEER unit which is the most efficient heat pump on the market. If there was any system that was going to work electrically this was the deal. What follows is the work to get it functioning in a van.
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Old 11-22-2017, 12:29 AM   #2
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Default Re: OFF GRID battery powered AC/Heat. Fully functional.

To handle the first challenge of powering a residential heat pump assembly it required thinking outside the box at residential inverter systems because they had the ability to produce split phase 240VAC at 60hz. What I went with was with components through Schneider Electric which is Conext (also known as Xantrex). The inverter is the Conext 4024 which stands for 4000w at 24v system. I went with the MPPT 150v 60amp solar Controller and two Tesla S battery modules wired in parallel to store the energy maintaining the 24v system. The batteries are rated at 5.3kw each and 232ah. So when they are run in parallel they have 10.6kw and 464ah. That can be a little confusing for people who are used to 12v ratings so to put it in perspective it is around 883ah at 12v.
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Old 11-22-2017, 12:34 AM   #3
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Default Re: OFF GRID battery powered AC/Heat. Fully functional.

To be able to convert power you must first generate power and that will be handled in these next couple posts. With a 170 there is some pretty decent real estate available on the roof IF you don’t plan on placing a roof mounted AC unit. I had one goal, maximize solar capture and also have space to have a MaxxFan unit for ventilation. What was used was (3) Grape Solar 265W home panels mounted to a VanTech roof rack. (If I did it again I would just make my own rack assembly with 8020 but hindsight is always clearer) that gives me in theory 795W available (even though I have had it produce 852W prior)
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Old 11-22-2017, 12:40 AM   #4
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Default Re: OFF GRID battery powered AC/Heat. Fully functional.

Solar is great but it has its limitations. What needs to happen is to be able to convert vehicle alternator generated power while engine is running to house battery available power. So a little history on how my van was originally constructed. It had the optional 220amp alternator and the Aux 100ah AGM battery located in the engine compartment. The issue comes from vehicle power is 12v and my house battery system is 24v. You can’t just connect up my house battery to the vehicle electrical system because they are not compatible voltages. I could have opted to install a 24v additional alternator but I’m not sure it is necessary at this point. What I did was work around it by extracting power from the vehicle Aux. battery circuit and converting it into 120VAC through a 1000W Xantrex inverter. This unit was mounted under the passenger seat and is remote controlled so I can turn it on or off when needed. Basically 2awg wire was run from drivers seat base to passengers seat base and then the output from inverter was then fed back to the Conext inverter/charger. System thinks I am just plugging it into shore power and gladly accepts the power and can even accept all of the solar power I throw at it so in theory I can have upwards of 1700w charging the battery while driving down the road on a sunny day. Since I can adjust the amount of current draw from shore power I adjust it to pull 8-9 amps which translates to approx 900-1000w which is the continuous rating of the inverter. Now the battery has a way of getting replenished even when the sun is down and engine is running.
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Old 11-22-2017, 12:44 AM   #5
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Default Re: OFF GRID battery powered AC/Heat. Fully functional.

So a little lesson on AC & Heat Pumps So you understand what is needed to fit this system into a mobile vehicle. There are two main components. The outside condenser unit that is the large box you normally see outside of someone’s house and it has the condenser coil, fan and the compressor assembly. Then you have the inside evaporator/fan assembly. This inside unit has the job of either delivering heat or cooling and extraction of humidity. This is the unit that is mounted on the wall near the ceiling in a home. If you have central AC these items may look foreign to you. The image shown here is the outside condenser unit with one cover removed. First challenge was “where in the world do I put this thing so it can do its job?” First off it needed to be mounted on the outside of the van AND it needed to be mounted vertically. That is because the system has refrigerant oil that helps the compressor and if you just install it on its side then the compressor won’t have the proper oil flow. I decided that I did not want to install that unit on the back of the van because 1) it’s ugly and 2) I wanted the ability to install a bike rack on the rear. So what I did was take all of the components (everything black and shiny copper) out of the outside unit so it could be installed horizontally in the area where the spare tire used to sit.
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Old 11-22-2017, 12:49 AM   #6
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Default Re: OFF GRID battery powered AC/Heat. Fully functional.

What you see here is all of the heat pump “guts” that were cut out of the outside unit and then remounted on a plywood frame that then got installed in the garage area over the wheel well. ( I will be doing further modifications to this setup to better isolate any noises coming from compressor and if you take on something like this DM me and I will explain what steps are needed) doing this allowed the weight of the outside unit to be dramatically reduced and the compressor to remain in correct orientation. How the compressor was joined to the outside unit was special flexible refrigerant lines which are basically stainless wrapped rubber 800psi lines
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Old 11-22-2017, 01:01 AM   #7
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Default Re: OFF GRID battery powered AC/Heat. Fully functional.

Once the internals were removed that left the condenser coil and the fan unit left. There was some work done on the electrical harness to extend all of the wiring approx. 6 feet. The support for the outside unit was accomplished with SuperStrut and 1/2” threaded rod. Also there was a section of the outside unit that needed to be sealed up where the electrical housing entered into the fan area. 1" rigid foam was used so when closed up the fan would have maximum pull through the condenser coil. Also any holes that were previously used for bottom drainage was sealed up with HVAC aluminum tape to ensure maximum pull with the fan.
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Old 11-22-2017, 01:15 AM   #8
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Default Re: OFF GRID battery powered AC/Heat. Fully functional.

Very interesting, thanks!

Did you consider mounting the condenser and fan on the roof rather than under the van? I'm concerned about mud/snow/road debris affecting performance, although a roof mount would have other issues.
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Old 11-22-2017, 01:17 AM   #9
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Default Re: OFF GRID battery powered AC/Heat. Fully functional.

I debated for awhile on where to place this unit. I first started out thinking I would do a bumper mounted storage box and somehow custom design the box to hold the condenser coil and fan unit but that was quickly scrapped when I realized that I could make some basic modifications to the bottom side of the van where the spare was mounted. There are two hang down brackets that the front of the spare tire frame attaches to. Those two brackets were moved upwards with the persuasion of a BFH so they were parallel with the van floor. That then gave me a surface that I could hang the unit from and have proper clearances. The unit was hung using the 1/2” threaded rod and double nutted top and bottom so not only does it hang in proper place but also to prevent vertical movement of unit when hitting bumps. Air circulation is key so what was accomplished was 5" of clearance between van floor and condenser intake on top and over 7" clearance to area on back bumper. By using the threaded rod like I did it restricts movement up or down ensuring that when a bump is hit the unit won't move upwards and crush the case. The two rear rods were just straight and the two front were bent to give a 90 degree end that allowed me to insert into factory holes and then double nut it tight so it couldn't work its way out. Finished ground clearance is 12" and actually now closer to 13" now that I upgraded my tires to 235/85/16.
The ends of the threaded rod and the bracket overhangs still need to be chopped off and the unit painted a flat black so it won't be visible.
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Old 11-22-2017, 01:22 AM   #10
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Default Re: OFF GRID battery powered AC/Heat. Fully functional.

Everything in a van is a compromise. If I mounted it on the roof then I was giving up some of my solar panel real estate and it would then be in direct sunlight which is not the ideal situation for maximum efficiency for cooling. Also you need airflow on both sides of the condenser so by the time you have it elevated it becomes a height hazard. My feeling is there will be some residual road grime and filth that accumulates on the condenser coil. My plan is to have a 1/4" copper pipe "wash hose" that I connect up to my onboard hot water heater so I can wash it down every so often when I see it filthy with pressurized/heated hot water. The unit is designed to be in adverse conditions so it has special coating on the coil for salt air environments.
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