I don’t, sadly.
Now, with modular balance leads
Have you done any long-term testing of the plastic under load? What have you seen?
I’ve done something similar but for just very small battery packs…2 to 6 cells for varying cell types. A problem I’ve run into with 3d printing polymers I’ve used is that they didn’t stand up well over time. After about 1 year or so, the plastic split between the cells due to the forces applied to assure each cell has a solid electrical connection. This usually caused loss of power from the pack. When I tried to “lock-down” the cells with less force to reduce the load on the polymer, the electrical connections began to show intermittency and overheat (I suspect) due to the less solid and perhaps lower-surface area connection with the cell contacts.
Do you have pics of the setup?
I am thinking of doing a pack for my ebike - your sets would be awesome for that.
How can I get some to test? I am already thinking of how to connect the separate modules to each other so that they don’t “wobble” around (on a bike I don’t have an enclosure that holds them - but the empty screw holes could be useful to somehow screw the individual modules together). On a bike I will probably need some rather complex structure to perfectly fit inside the frame. Vibrations will be low (impacts not so much though on a downhill bike).
Yeah would be nice to get more details about your setup and how it get wore out over time. what type of filament did you use and what’s your print setting? would be nice to see a model too.
As for long-term testing, I haven’t been able to find established research on 3d printed material aging under stress (please let me know if you find something). My understanding is PETG is a great material with very little drawback for our application. about 70C glass temp, Pliable, durable and good layer adhesion. Check this article out more about PETG.
I have addressed some concerns on stress due to over tensioning the parts. I have tuned a lot of dimensions so that everything would fit within reasonable tolerance for good compression while not putting too much stress on the 3d printed parts.
@Maxid thanks for you interest. I’m currently a little busy on school rn. I’ll make an update to reply to all interest maybe in a week or 2. Yeah, you have noticed it. those empty holes are great for a few reasons. I decided to leave them there so that you can chain holders together and attach to an additional piece that you would use to screw into your longboard deck like @mishrasubhransu’s for the NESE. (i have not CAD one out yet but it should be easy few hour job with testing)
A bit of 3D printing stuff in my experience, maybe not super applicable to these, as PETG may serve this purpose just fine.
I find myself not using PETG for eskate applications, most of the time. Contrary to a lot of articles on the internet, I’ve found PETG to be fairly brittle. It’s still strong and somewhat flexible, but if you are doing less than 10 layers or 6 walls on two sides, I find it can’t take a ton of stress. For these hardware compression cells, I think (with testing) it should be fine, as long as you aren’t compressing with too much force. PETG is great for larger parts though IME, parts that have a lot of extra mass to take flexing stress off smaller areas.
Nylon is king when it comes to strength, but I am afraid unless you find the right type of nylon that is extremely rigid, nylon might be a bit too flexible for these compression cells… but as long as your compression bolts are spaced evenly, you could torque these down a CRAP TON if they were made out of nylon and not have to worry about cracking. I’ve had only one part made out of nylon ever outright break on me, and it sheared across the whole part and not the layer lines. With PETG, i’ve had maybe a third of my parts just crack, like stress fractures, that I ended up just replacing those prints with the same parts made out of nylon.
Thanks for you input and saying sorry ahead of time if it sounds too defensive.
Yeah Nylon is definitely a great material with a lot of advantages over PETG. Personally I have not print with nylon before because it requires me to do numerous more upgrades to my cr-10 which is already very modified. (I’ll eventually get there, making this from a $300 machine to $600)
Petg is brittle if you compare it to nylon and I totally agree that nylon can be too flexible too. It’s all about finding the right material for the use case rather than the absolute optimal. There are also a lot more mix filaments that are great and available on the market: Pla-CF, PET, Nylon, Nylon-PLA, Nylon-CF. I definitely have a limited experience with filaments, but I find PETG reasonable for this application. it’s also widely used thus available at low cost. I will get to explore more material once we move on from 3d printing.
On a side note, I’ve heard about some self extinguishing plastics that’s also super interesting.
Are any plan to made a design for 20700 cells?
Basically I’m down for any request and then I’ll make that available for everyone.