I have some ideas, but need to do some prototyping and testing.
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Well the module seems to stick pretty well now.
There’s a couple sheets of cardboard between the bottom of the battery module and the frame to provide some cushion/damping against vibration.
Stays on, or doesn’t fall off at least.
I’ll add a one or two more cross bars for extra support when I got more AL.profile
There’s a little bit of extra/unused space between charger and battery module, but I’m not planning on stuffing anything there. I think I’ll just leave a little bit of breathing room there, as the charger does heat up quite an amount when going full blast for hours, so I don’t want it to touch the pack.
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are those 3D printed brackets going to hold the entire weight of the battery bouncing on crappy pothole filled pavement and/or off road?
I would do a test with sandbags as weights and see what happens. Doesnt have suspension to soften the blows either
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That’s why I added some cardboard between the trailer frame and the battery frame to act as a shock absorber. Also it’s gonna be on pneumatic tires and they do act as a light suspension with the air inside them.
I’m gonna add a couple more cross braces under the battery, so it’s weight is better distributed over multiple brackets, but these brackets can be surprisingly sturdy, especially as they are bolted to the AL.profile and they are not long, so there isn’t any long moment arms really anywhere, which would break the printed brackets.
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This will also help reduce the trailer wiping around at the cost of a larger turning radius but that’s not a bad trade off for this application. Not sure what the board will do with the extra weight on the back trucks. Might change the steering characteristics.
Finally got the trailer hitch and bar attachment prototyped and iterated, not yet tested on the board with the trailer, so after I get the needed supplies I’ll be able to get some testing done to see if there is any problems with the mechanics.
The main attachment of the hitch to the hanger of the Trampa Vertigo trucks uses the opening available on the hanger itself to have 2 M10x100 bolts run through it. This then provides a solid mounting point to have a vertical bolt that runs up between the 2 bolts to a nut.
The gap between the bolts is small enough that the nut can’t escape out from between them, so it should be pretty safe, unless you get absolutely catastrophic failure where the whole block splits.
To make the attachment to the trailer bar more secure there’s gonna be 2 M5 bolts running through the AL.profile itself, one horizontal and one vertical.
In case you’re wondering where the PU bushings for the hitch attachment point came from, they were from a normal skateboard truck. This attachment allows free swing in the horizontal axis and the bushings should allow for any limited roll and pitch changes.
I also made a custom hand nut wrench, based on the one I use for my wheel nuts, so I can easily attach and detach the whole trailer hitch and the trailer with it, just unbolt the vertical bolt and the whole trailer is then detached and in reverse to attach it back to the board.
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Rebuilding the frame and slotting all the needed nuts into the AL.profile. Printer is gonna be running continuously for a while. The length of the tow bar is gonna be adjustable, but I think ideally it should be as short as possible, while still not letting anything rub between the trailer and the esk8.
The added downwards pulling weight at the tow hitch is pretty reasonable even with the battery pack and charger attached. I’d say it’s around ~10kg of added weight.
I’ll try switching the rims on the trailer wheels back to Trampa Superstars, as the current ones have the added -15mm offset and I don’t think I’ll be needing quite that much offset to clear the tarp on the trailer. The trailer is about 53cm wide at the wheels and the esk8 is 44cm atm, so I wouldn’t mind if the trailer was a bit narrower.
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Are those hubs for the board 3D printed?
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Yes, more on those and the ones that are on the trailer here:
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lol that is hardware dense part! looks complicated but actually so simple you just added another kingpin to the truck 
Carry a spare print! add a cable for failure more too?
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I had also thought that a safety wire would be a good idea as a failure backup. I’ll probably go for rope, as the weights and forces aren’t as big, as on a real car trailer though.
I have an idea for a simple solution for it.
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Here a couple more close-ups of the trailer hitch itself and how it’s put together.
Here’s the part that bolts onto the hanger of the truck.
It turns out that there are slight differences between old and new trampa trucks, specifically in the hanger itself. Brown is the old version, red is the new version with the end of the hangers being machined square on the new version.
The newer hanger has a slightly different hole size and shape. It took a couple hours to slightly tweak the hole-adapter design.
I went for the first field run with the trailer in tow today. No tarp or anything else attached to it yet, but just to test how it behaved behind the esk8 without any extra weight on it. Slightly bounce, due to it being so light, but it stayed behind for the whole ride, so success, although I did stop a couple times to check and tighten a couple of bolts.
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Such a cool project and adventure! Loving the build progress.
And I know your in kind of the opposite environment, but I’m really hoping the finished trailer comes out looking like this. 
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Have you considered putting something like a small 100w solar panel on the top of the trailer (looking at the dimensions it looks like it would be a great fit / roof) with the usual solar charge controller setup. Wouldn’t add too mich more weight.
Assuming some ok sunlight and typical esk8 efficiency…you might find you need to charge significantly less…
Afterthought, if you rode efficiently… I wonder how close you could get to not needing to charge at all 
Great project and work though! Looking forward to your journey 
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I’m not sure how possible this would be just based on the fact that pulling only 100W from a power source for ESK8 would be nearly impossible I think
It’s a good note though, it is possible you would need to charge significantly less.
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Lol you would run the solar controller into a boost converter into the bms into the battery and run it like a charger… Not run directly off it!
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Yeah I know how it works I’ve built solar stuff before
I meant net power usage
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Ahh got you. Can you explain what you mean though? Not sure I understand your point? (PM if you like, so we don’t derail @SimosMCmuffin beautiful thread! 
)
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Okay well to keep it on topic, my point was if he were to add 100w of solar charging, I think the main benefit would be that you might not have to charge as often.
You had mentioned earlier you wonder if riding efficiently could get you to the point where you didn’t need to charge. I think that is impossible with only 100W 
If he were to take a break though and it’s sunny, maybe he could get 1% or 2% charge
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Oh got you, agreed completely, but in theory you might be able to get more than 100w of panels and get close enough to make a huge difference!.. But agreed you’d probs need like 500w worth of panels tbf
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