I see what you mean. Looks like there’s what, 1? 2? struts holding it up and secured? Yeah, a few more for the final thing, help keep it from flexing.
I do like that simple, long and cheap hinge setup. No way that’ll come apart, and if it is everything else if flying around in the tornado anyway, so it’s the least of your concerns.
Those struts are borderline unworkable. There are three of them, but they’re a royal pain to get up and take down, so we’re going to replace them with an overcenter elbow sort of setup (think “folding table”). They’re fine for prototype work, but if you’re not careful, it’s too easy to punch one through the back of a panel for a production model.
That long hinge will probably stay, though can skip all the bearing blocks on it…
Yeah, probably can just leave it with a rough tube welded on (or welded to a bolt connector) in which the rod can turn. Even if it’s slightly loose, I doubt the wind can get enough movement to put much force into it, although that is one advantage the bearing blocks would have. But, the bearings are one more thing to fail. Then again, the bearings are sealed I presume, which means something less prone to rusting together. Unless you use aluminum for the rod & tubes for the hinges.
The bearings were there because I figured with the weight we’d want something to take the load over the plain bearing surface of the welded brackets there. Turns out 6 3" wide 1" aluminum hinges slides over that hinge pin quite nicely by itself!
Also a great success to design and weld, if I do say so myself.
Fun though the aluminum hinges were to tig together they themselves are a bit of a vestigial design choice left from an earlier iteration of panel-rack. V2 will have hinge pin replaced with a piece of box tube and a line of weld-on bullet hinges down the inside instead.
900W golf cart charger installed and hooked to the 120V inlet - and tested with my office generator, though not under full load (my generator is fine with 900W and the battery bank is exceedingly full, stuffed to the gills and then some).
Tonight should be… hopefully very boring. The trailer is getting used to host a movie night in a park without any other power. Capacity as measured in the morning a couple days ago is… oh, hopefully will work, but is a bit on the “Eeeennnhhhh…” side. Capacity with warm batteries, which I’ll have today, should be a lot better (an extra ~1.5kWh by the datasheet), but draw may be slightly heavier, which will impact capacity. If it’s looking iffy, I light the generator and dump 900W in, which is more than enough to extend our runtime very significantly (I’m hoping for ~1.3kW load, wouldn’t have a problem with ~1.5, around ~2kW things are increasingly iffy with runtime).
But I’ll report back!
Well, that went absolutely as well as could be hoped for! Total and complete success, and we could have gone another few hours!
The Volt tows the trailer fine. Energy consumption is up by about 50% from rolling around empty, which is actually not nearly as bad as I’d feared for putting a large box behind a fairly aerodynamic car. It tucks very nearly behind the car.
With the small fan, which struggles a bit to get the screen up but can do it eventually, the whole setup, running the movie, pulls about 20A off the batteries (so right around 1000W), with spikes up to 25A or so during bass rumble. I expect something like The Greatest Showman might have pulled a good bit more power, but I also fully expect the system to have the required power to accomplish feats of blowing subs, should you ask it to.
It ran the movie perfectly, and we used 42Ah out of the battery bank. I’d tested it (on cold batteries) to 140Ah (to low voltage cutoff - whoops… wasn’t quite planning to go that far), and warm batteries leave another good bit of capacity - another 30-40Ah, so we probably had 180-200Ah real capacity to play with. So, total success! I could have been charging the car during the movie at 120V and been fine too!
That’s a beaut! I’ve been designing a trailer in the opposite direction: bicycle towed, but for “working from the park” instead of working from home. It would only need one panel and battery. The real problem is no (good) connectivity except for cell phone.
Alternate thoughts: If you’ve already got a hybrid, how hard would it be to parallel a roof mounted solar panel to that system? From what I’ve read, you just need to put the key into the ignition and put it into neutral (to trick it to stay “running”) and then it’ll automatically spin up the engine when the draw is too great / the battery gets low.
And on the pure EV front, I’ve heard that the Tesla has a traction-to-12v dc-dc converter in the 2000W range. Caveat, the Tesla warranty prohibits this, but I’d be curious to see if it would hold up vs “the Magnuson-Moss Warranty Act of 1975 that states a dealer must prove that after-market equipment caused the need for repairs before it can deny warranty coverage. (See Edmunds.com article: What Voids your Vehicle’s Warranty?)” from EV Extend - Inverter Kit for 2016-2019 Chevrolet Volt
Yes, I’m waiting for V2G, as I’m urban and only need emergency battery backup once or twice a year.
Why not just put a medium size lithium battery and inverter in your backpack? A 500Wh battery would run a laptop for quite a few hours.
It really, really depends on the car and system. Older Priuses don’t seem to really care about anything but voltage, so they’d tolerate it just fine. Newer stuff, to include the Volt, probably won’t like you messing around on the high voltage rails doing stuff it doesn’t believe should be happening. That’s deeper into car hacking than I care to go, though - that’s “I have a Volt, disassembled on my office bench” sort of hacking.
If you’ve got a 2kW DC-DC converter, hanging a 1000-1500W inverter on that shouldn’t be a problem for home backup. I would expect if you fry your 12V battery or DC-DC converter, you’d be out of pocket, but isn’t yours out of warranty anyway?
I wanted a chair, a desktop surface, shade (summer was mostly 80F), food, drink, etc. At a stretch, perhaps bring my 4k monitor too. At some point in the future, if I ever get my hands on a Starlink dish (that’s the current blocker to enable the trailer or work-from-state-park-campsite), it’ll need (just one!) solar panel to keep it running for a full day. Yes, other options include using the existing chair and table surfaces at the park, but I really don’t want to sit that close to unknown people. I’d rather sit by myself in the middle of the baseball field (i.e. 50 yards from the nearest cement walkway). Yes, that’s a downside to urban life. The nearest park is only 5 blocks from my house; I could practically walk the trailer there. Other options include 5 parks within 5 miles (hence the bicycle plan).
The largest Li pack I currently have is 3S@20 AHr (on my bicycle coincidentally), or about 200 WHr. Many high end commercial ebikes come with one or two 400-500 WHr packs! The only other batteries I have are SLA for my APC SmartUPS at the house.
I don’t yet own a hybrid or EV yet, but in our next round of car purchases in the next 5 yrs will be at least one EV. They’re both 2014, and we usually get about 10 yrs of life out of them, though the pandemic will stretch that a bit. In particular, I am watching Aptera. The concept of a car with 1000 mi range by making the vehicle more efficient (aerodynamic) makes me happy. But the EV market is evolving rapidly, so they might fold (again) or something else amazing and new might come out.
Hm, some cars already come from the factory with giant 120 VAC inverters; Hyundai Ioniq “V2L”; 3.6kW. Ford F150 Lightning 9.5kW! My (diesel) car came with a tiny 150W accessory inverter, enough for a laptop, but that requires the engine to be running. Ah, found a reference that the Volt has a 200 A DC-DC inverter to power the 12V systems from the traction pack; no need for a custom inverter running off 300 VDC (or whatever they run at).
Challenge I see with you saying you’ll need just 1 solar panel, what size do you mean? 30W? 50W? 100W? If you’re talking about the fold down ones, sure they’re more compact, but you’re still going to have a fair amount of bulk for meaningful production. And you’ll need to haul the appropriate charger for lithium, which means not the small cheapo PWM, but something bigger/more. And then the battery separate, as well as separate inverter (unless you’re doing DC-DC direct to your laptop).
Honestly, I’d get something like EcoFlow RIVER + Extra Battery Bundle, >%00Wh, small and compact, high power rated output at need with 12v/12v solar panel input for charging. They do have a 1100Wh with more capabilities.
The official folding solar panels they sell are crazy expensive IMO, as long as you go for standard 12v panels it’ll handle it fine, mine (without the extra battery slice) does. Just remember you may not get as much power as you think from the solar panel unless it’s in optimum conditions. I plan on 50% rated wattage, just to be extra pessimistic. That’s with actually being in the sun, by and large, no shade from trees or anything. That can really cut into the power generated from even partial shading.
This made me think of you guys. 
Just bring a panel to charge it? I have a little 60W folding panel (this one)Amazon.com that was 120 (so $2/w)
Remember, I planned to dual purpose the panel for shade, so tiny panels won’t do much more than shade my forehead.
The V1 starlink consumes 100W continuous, so yeah, a old 200-300W panel is probably in the right range.
Craigslist (SF Bay Area) has used panels for around $100 each, which would work just fine for me. There’s a business in Arizona that sells new and used panels too. A few years back, one of my coworkers figured out that hauling panels from there was still cheaper than buying new! of course, that’s only true if you consider your time free 8>
Now that I am looking at craigslist, they have solar powered trailers for $12-14k! I just don’t do all that much off grid stuff; I live in the middle of the SF Bay Area. Nothing is all that far away unless I decide I want to go out to a state park or something (Pinnacles comes to mind)
@kjw I thought you said bicycle towed…
I mean yeah, an old house panel 200-300W will work just fine. They’re big and heavy though. I suppose you could put it on a bike trailer, although you might have to have it vertical (warning, big wind sail to have the trailer tip over!), might be too wide have it horizontally. I actually found the couple of panels I have on CraigsList locally, someone who was selling off his old house panels. Got them CHEAP. Although it’s 56v VoC I think. Somewhere thereabouts. House panels are higher voltages and with multiple strings in serial to have high DC voltage to handle the wattage, so you don’t need giant wiring to handle the amps.
Or are you referring to a motorcycle? Yeah, if a motorcycle, I’m sure you can DIY an old house panel onto a motorcycle trailer, although you’ll definitely need an MPPT charger that can handle the input voltage to bring it down for your battery pack if you’re using a “12v” LiFePO4 battery pack. You’ll probably need one anyway, one that knows/understands Lithium well enough, as well as a proper BMS battery pack, even if you use a DC-DC buck to bring it down to 12v for running stuff.
Thanks for that, lot of neat ideas in that setup! Those air cylinders are fun to watch.
I’m a bit lost now. Bicycle pulled trailer doesn’t imply particularly large, and certainly not “more than one house panel.”
I’d rather have a long drive than spend time consuming entertainment, especially if I can turn a profit on panels. 
Oh man. Those are the DC Solar bankruptcy auction trailers. Look them up if you want an awfully good yarn ending in a literal Ponzi scheme and jail time. They’re probably fine, but if they’re under 8k, I’d be very surprised. Not too many people have the trucks to move a heavy double axle trailer, and I think they’re actually comically underpaneled for what they are.
Whaaaat? You mean to tell me you think the lend/lease/venture-capital/ponzi scheme scam company skimped on their engineering costs!?
The Mercury News: One-time owner of Bay Area solar company sentenced to 30 years in prison for billion-dollar Ponzi scheme. Benicia: One-time DC Solar owner gets 30 years in Ponzi scheme
Excellent…
The small set of batteries in the trailer may have looked like it was rather rattling around in a cavernous trailer - and, in fact, it was. The designed set of batteries for it, which was largely unobtanium for a year, is now present in the trailer, awaiting a bit of welding on the hold downs. The process involved an engine lift, a 2x4, and eight Trojan SPRE 06 415s, at 118 lb each.
Those should hold loads for an awful lot longer, and the trailer has a busy summer lined up ahead of it, with a range of places it’s likely to be working.
Now to get the website finished.
