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  1. E

    My "Mark 2" solar trailer

    Thanks, but yeah rigid panels are too heavy for my application. Solbian SP36Q flexible panels would be perfect, but they're ~800€ each and would be hard to source in New Zealand. I'll probably go down that path if I can't find any better options though.
  2. E

    My "Mark 2" solar trailer

    Unfortunately I had a wee oopsie while on tour recently, and one of the panels hit the ground. There's visible damage to one of the cells where the supporting honeycomb structure deformed under it. With the two panels under the same illumination, the damaged panel had a Vmpp of ~17.9V and the...
  3. E

    My "Mark 2" solar trailer

    It's been a long time since I've posted on here, figured I should give an update on this project. I ended up solving the torsional stiffness problem basically just like this - some horizontal "spreaders" and cables making triangles. I'd previously tried this sort of thing, but what ended up...
  4. E

    Breaking spokes on GMAC laced in 20" cargo bike wheel

    Thanks for your thoughts everyone. After buying some Polyax nipples and trying them in my U663 rim: yes, that's absolutely the case here. The hole diameter (really eyelet ID) combined with rim thickness limits the possible angles the nipple can exit the rim at. Even with the rounded Polyax...
  5. E

    Breaking spokes on GMAC laced in 20" cargo bike wheel

    Your observation is correct. That sounds like a plausible explanation for sure, but it'd be pretty hard to prove/disprove. I'm running CA3-13v2S firmware on my CA, which only supports engaging regen via pulling the brake lever and then using the throttle to control regen strength. That results...
  6. E

    Breaking spokes on GMAC laced in 20" cargo bike wheel

    Yeah given we live at the bottom of the world and sourcing weird bike parts isn't easy, maybe that's a good idea! The Ryde Andra 40 isn't particularly costly either. Maybe I should also keep enough spare spokes on hand to do a rebuild, given I have to get those from overseas too (single butted...
  7. E

    Breaking spokes on GMAC laced in 20" cargo bike wheel

    Yeah the ~75° spoke angle isn't ideal and is causing spokes to be a bit bent. I'm keen to do something about it. Would bending around the holes like that leave the eyelets intact? They look pretty thin, maybe they'd pop out if I bent the aluminium they're sitting on? I'd be reluctant to...
  8. E

    Breaking spokes on GMAC laced in 20" cargo bike wheel

    OK, well if we laced it that way (elbows out on both sides) the spoke calc says that'd lead to 45:55 tension ratio. That's still an improvement over 40:60 and it'd mean all of the spokes are snug against the flange. Seems like we'd be addressing two possible causes that way instead of just one...
  9. E

    Breaking spokes on GMAC laced in 20" cargo bike wheel

    OK, thanks, we'll rebuild it with the elbows around the other way - outside on drive side and inside on non-drive-side. Calc says that'll give us a 50:50 tension ratio instead of the 40:60 ratio it had before. Noted. I assume he used the normal squeezing-of-pairs method for stress relief when...
  10. E

    Breaking spokes on GMAC laced in 20" cargo bike wheel

    No - he used the standard Sapim Strong nipples (14mm long). Neither of us knew about the Polyax nipples. They don't seem to be available from the NZ Sapim distributor (neither are Sapim Strong 13g-14g single butted spokes - we have to get those from Grin). That seems like a good idea though...
  11. E

    Breaking spokes on GMAC laced in 20" cargo bike wheel

    Hi all, I have a Yuba Sweet Curry longtail cargo bike. It has a 20" rear and 26" front wheel. I converted it with a GMAC (taken from another bike) in the rear wheel, laced into a DT Swiss U 663 rim and Sapim Strong single butted spokes (13g-14g; 115mm long as per Grin spoke calculator). It's...
  12. E

    My "Mark 2" solar trailer

    It's been quite a while since I've posted here, figured I owed you all a progress update. I've gone ahead and mostly built the trailer now. All the pieces fit together perfectly first go (all those hours in CAD paid off) and it looks basically just like the aluminium prototype did, but with...
  13. E

    My "Mark 2" solar trailer

    I've also made some progress on the light sensors - I actually designed and assembled these a couple months ago, but hadn't got around to posting. They consist of a PCB with a small STM32 μC, 4 OP950 photodiodes 90° apart (chosen because they have a viewing angle close to 90° and reverse light...
  14. E

    My "Mark 2" solar trailer

    I've finally found some time today to work on this prototype. I've built a full-sized prototype as discussed above, using 25.4mm ID * 1.35mm wall thickness aluminium tube with 4 slits roughly cut on each end with a hacksaw. I made some timber plugs to insert into the DragonPlate connectors and...
  15. E

    My "Mark 2" solar trailer

    Maybe I'd get away with a rigid attachment and a nice wide tyre on the trailer, I'm not sure. It was easy enough to include the suspension in the design though, it's not very heavy/costly, and my chosen air shock has a negative pressure chamber for light-load applications. So I'm hopeful it'll...
  16. E

    My "Mark 2" solar trailer

    Yeah I've used MyUS.com quite a bit for having things shipped to NZ, but the cost does still add up. They add a bunch of fees to each parcel that you might not know about if you only look at the "shipping calculator" section. Still, they often end up significantly cheaper than many US-based...
  17. E

    My "Mark 2" solar trailer

    No worries, you don't owe us anything :) Interesting results though. I'd have expected the Genasun to be a little better steady-state too, figured they'd have better MOSFETs than the CTK-EV-300. I guess the additional cost still gets you a very robust, well-engineered unit with excellent MPPT...
  18. E

    My "Mark 2" solar trailer

    Okay, so after spending several hours in Fusion 360, I've updated the model to lower the panels. I managed to get the panel height above ground (assuming panels are parallel to the ground), down from ~775mm to 690mm. I achieved that by reducing the distance between the top and bottom booms by...
  19. E

    My "Mark 2" solar trailer

    Yes, it's very productive! I should have posted my Fusion360 model weeks ago, it seems to have prompted a fair bit of discussion. I think I could cope with adding a layer or two of 45° braid to the OD of an existing tube (though yeah, it'd be all new for me!). Exterior would be stronger too of...
  20. E

    My "Mark 2" solar trailer

    Another thought I had overnight - why not just add a key to the connector faces? i.e. mill a slot, say 3mm deep and 6mm wide, into the faces of the relevant connectors. Then press in a piece of, say, 6x6mm key steel, with some retaining compound to hold it if needed. I couldn't mill the slots...
  21. E

    My "Mark 2" solar trailer

    No worries. They're great panels. It's hard to find semi-flexible Chinese panels that actually meet their specifications, but these ones seem to (though I don't have the insolation meter necessary to prove it). I'm guessing that someone in Australia has bought a few container-loads of these...
  22. E

    My "Mark 2" solar trailer

    Thanks! Though I was thinking that maybe congratulations should be withheld until I've actually built the thing and proven it works :LOL: Good to hear you've got some positive experience with this connector system. I thought it was a little suspicious that I haven't come across anyone else...
  23. E

    My "Mark 2" solar trailer

    Thanks, and I appreciate the consult. This design (bespoke single-wheel CF) certainly seems like it'll be harder to get right, but the weight savings will be very noticeable. I promise I won't blame you for the inevitable failures before I get it right! I did a tour over the summer with the...
  24. E

    My "Mark 2" solar trailer

    Thanks for your thoughts. I'm definitely concerned about torsional flexing down the length. It was pretty easy to add bracing to help with the 'vertical' rigidity. On the Mark 1 trailer, 'vertical' flex down the length was a problem so perhaps I've gone overboard with 'vertical' bracing on the...
  25. E

    My "Mark 2" solar trailer

    Thought I'd better offer a progress report on this project. I've spent a lot of time learning enough Fusion360 to design the trailer in CAD, so that I could calculate the carbon fibre tube lengths and avoid any expensive screw-ups. I'll need to use quite a few DragonPlate CF tube connectors...
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