Red's electric apu thread

Discussion in 'Ask An Owner Operator' started by RedForeman, Jul 28, 2022.

  1. RedForeman

    RedForeman Momentum Conservationist

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    My install seems to be getting some interest where I've mentioned it here and there, to the point of hijacking or sidetracking some other really good custom cab hvac discussions. By request, I'll try stringing together something a bit more collected. Along the way, I'll try to keep up with questions best I can. I been doing a 4 day loop on the truck lately, with Monday-Wednesday being the worst part of it. Then hometime is more or less catching up on everything I didn't do while on the road last week, in one day or so.

    If you don't get a reply in a few days, don't take it personally. I just don't have the time to be on here like I have had in the past. I'll add pictures over time, as I did take a few throughout the install. Just not all at one time, so sometimes it takes a minute. Or, I don't mind focused shots of anything in particular. I really didn't document things very well. As this thread develops, I'll offer insights of why I made certain choices, or didn't do others. What's worked what hasn't. Hopefully another data point to guide someone else toward a better install than this.

    Here's the short version. My truck is a '22 Mack Anthem 70" sleeper. I already had a Giandel 2200W sine wave inverter installed, connected to the batteries with 2/0 cables. I installed a 120V, 9000 btu mini split heat pump. Then had an old set of really great Northstar (actually Batteries Plus X2Power branded) hybrid group 31's laying around, so swapped those in for the generic Mack AGM batteries. I added 480W of Rich Solar panels on the roof with their 40A mppt charge controller. I also have a '20 Anthem my son drives. I have the solar for it, but not installed yet. Same hvac and inverter, and the factory battery set.
     
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  3. RedForeman

    RedForeman Momentum Conservationist

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    It's ugly, but here it is. Their flexible kits are all increments of the 67.3" x 26.0" panels at 160W each. Flexible Solar Kits

    I actually got the 640W kit. I thought I was going to fit a 4th panel horizontal, between the spoiler and the other 3 panels. It measured out good, but the compound curve and seam right there was worse than I expected. That got ugly and messy and I elected to just get the 3 installed and run that for now. Panel 4 is still in the box. I'll figure it out eventually. Or not.

    My advice: DON'T use these big panels. Use more, smaller ones. These are really more suitable for a flat roof, like on a travel trailer. They flex, but not much, and really will only follow a single curve. They are stiff and absolutely won't lay flat on the typical compound curved roof of a sleeper truck. You can see where the side edges lifted off with mine. Gorilla tape is great stuff, but also not up to the task either as you can see. I have some 3" Endurabond tape and spray primer for it, just haven't had a chance to get up there and get-r-done.

    Also, the adhesive is some rubberized goop that you get one try with. If you don't have it perfect, it's too bad. You can see the gap between center and right. Center and left actually overlap about 1/8". The install was done laying in the bucket of a towable power lift. Long story short, that was the best solution to get up there, given location and time to get it done. Lining these things up is akin to sticking on a five and a half foot sheet of jello that sticks to everything it gets close to. I'm amazed I got it this straight. I already got the panels for the other truck, so will deal with it. If I ever do something like this again, I will not buy anything larger than 2' x 3' and just use more of them. Cleaner install at the expense of more wiring work.

    22-Anthem-solar-panels-front.jpg
     
  4. RedForeman

    RedForeman Momentum Conservationist

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    Mini split is a Pioneer 120V 9000btu heat pump. The one to get is their 22 SEER ultra high efficiency model. That's what's on my son's truck. When I ordered mine, they shipped a 20.5 SEER high efficiency (lesser model) by mistake and I didn't realize it until I was halfway through the install. Honestly the specs were the same in terms of battery consumption in cooling mode, with about 15% less maximum airflow. So I elected to take a credit for the lesser one and just finish it. It has not been a problem, and the unit cools beyond expectations. The main benefits to the higher efficiency unit is lower consumption in heat mode, and slightly more airflow as I mentioned.

    The outside mount I built out of 304 stainless. Legs attach under the cab at the bottom, flanges to the back of the cab up top. It's seriously over-built, so I expect the unit to dissolve into rust long before the bracket it sits on suffers any harm. Inside, I took out the top bunk since I don't use it. It's kind of big, so if you needed that bunk for storage, it could still work but would limit air circulation of course. I attached it to the back wall on the factory nuts that would normally have a cabinet mounted to them in a solo cab. There's a piece of 1/4" plywood attached to the wall, under the upholstery. The bracket the evap/fan mounts to is then screwed to that securely.

    Here's the inside and outside units.

    HVAC-frame-done-osr.jpg

    HVAC-frame-done-is.jpg

    ETA: this is actually the one on my son's truck. Same style install. The only way I could tell is the assortment of crap in the tray below the inside unit LOL. Both trucks are installed the same. The 20.5 SEER compressor unit is smaller on mine, so I had to improvise some 1-1/2 flat steel supports in the middle to mount it solid. I built my frame to the same dimensions I used on the first one. My first clue I had the wrong unit? When the compressor darn near fell through the hole in the middle when I went to set it up there.
     
  5. RedForeman

    RedForeman Momentum Conservationist

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    I'm starting to fade, but here's an important safety matter to know about these mini splits. They are designed to be installed in a house on utility power. You may ask "So what? Watts is watts."

    The important difference is: ac household wiring has a bonded neutral. That is, the neutral circuit is bonded to ground at only one point, usually at the service meter. All inverters sold in truck stops, and 99% of the ones that you will find in a truck, do NOT have a bonded neutral.

    Why is this important? A bonded neutral is required for the proper function of a ground fault circuit breaker. On the usual truck inverter, there isn't one. If you happen to get a short between hot (black) and neutral (white), chances are good you will end up with some energized parts on your truck that would hurt you if you touched them bare handed. A rare and unlikely situation to be sure, but without a bonded neutral it remains a possibility.

    How to fix this? Higher end inverters typically used in RV's have a bonded neutral and ground fault capability. You just have to buy a better one. Typically these style inverters are equipped with lugs for hardwiring circuits, versus the truck stop inverters that just have a couple outlets on the front.

    Of course, I learned this after the fact, so correcting this on my own to-do list.

    Disclaimer: I am not an electrician and will probably set myself on fire someday touching bare wires. Search the internet or pay a licensed electrician if you want more specifics about bonded neutral wiring and ground faults. I'm a poser with this stuff. Beyond my warning about this being potentially dangerous, you should trust specific advice from someone else.

    ETA: Those of you running portables or window units off an inverter should probably also pay attention to this. If you're using a genset, I think you're safe.
     
  6. The Crossword Trucker

    The Crossword Trucker Road Train Member

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    Thanks for taking the time to write this up for us
    This is exactly the kind of information sharing that forums do best and facebook could never do
     
  7. RedForeman

    RedForeman Momentum Conservationist

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    One more thing and I'll call it quits for tonight. Besides my inverter having a potentially deadly shock hazard, it happens to have inputs for solar too. At the time I bought it, I figured that's cool since I had considered doing that some day. Nice to have it built in. Digging deeper into the weeds figuring out what to buy, I discovered the built-in charge controller is crap. It works, but not ideal. Here's why.

    There are two types of solar charge controllers. Pulse Width Modulation (PWM) and Maximum Power Point Tracking (MPPT). Solar panel voltage is all over the place, depending on how many, how they're connected, and how much sun is hitting them. Truck batteries are 12V only, and float charge at 14V.

    The controller has to convert whatever comes in from the panels into useful, safe charge voltage. PWM just switches the input rapidly to achieve that voltage. It's not very efficient. MPPT dynamically adjusts the charge rate by monitoring input much more closely. Charge rate (amps) can be substantially greater with an MPPT controller instead of a PWM.

    Turns out, deep in the Giandell website, written in hard to read Chingrish, the built in controller in my inverter is PWM and capable of max 20V input, so really only capable of handling a single panel for a trickle charge.

    The controller that I got with my Rich Solar kit is a 100V/40A MPPT. That's 100V maximum panel voltage, 40A maximum charge rate. With the 480W 3 panel setup I have, voltage gets as high as 70V, charge rate as high as 35A in ideal sunlight. The built in deal would either limit charging severely, pop a fuse, or start a fire. Not sure since I never tried it.
     
  8. RedForeman

    RedForeman Momentum Conservationist

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    Thanks for that.

    I'm also trying to explain how not to do this where it matters. I must've logged a hundred hours reading internet posts, mostly from the RV people. As with anything else, most people like to brag about their successes but never mention the failures. hvac is pretty straight forward, but the solar stuff is too expensive and time consuming to make poor choices with. I also saw a lot of sketchy install stuff that I personally wouldn't do.

    That thing about bonded neutrals? I actually stumbled across that looking for something else. Some guy on an RV forum who is a retired EE wrote up a couple pages about it that my management degree just rolled it's eyes at. Good information is out there, but finding it is another matter.

    ETA: Facebook is an excellent source if you know where to look. Problem is that the good stuff is usually in members only groups, that won't show results in a site-wide search. The 9+ mpg group has a few interesting non-factory setups, as well as some interesting out of the box stuff if you have the money for it and trust the seller.
     
    Last edited: Jul 28, 2022
  9. 77fib77

    77fib77 Road Train Member

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    So did you add extra batteries. Or just swap them out?

    It's a good post you made pretty much an article.
     
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  10. skallagrime

    skallagrime Road Train Member

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    Got it, thats what i was worried about, ive got a kw midroof with no air dam, so im probably limited to 3 smaller panels (has a small but noticeable dip in the center of the sleeper), a 4th on the top of the cab if im ambitious

    Part of my problem has been which panels to get and what size. Getting to the point i may just have to build a flat surface air dam for up there and just mount to that (extra benefit, that would also give me an air gap so solar panel absorbed heat wouldnt end up transfered to the inside, extra downside, im sure its gonna whistle a LOT)
     
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  11. Ridgeline

    Ridgeline Road Train Member

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    Great write up

    the only thing I would change is going with LiFe batteries and get rid of the AGMs. You’ll get longer life out of batteries you can use under 50% SoC.
     
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