The goal of this project is to design/build an aesthetically pleasing, elegant solution to carry a pack of LiPo batteries on my back. I've been playing around with using PVC fence posts to hold lipo batteries for a little while (see the Kona build link in my signature) and have found this to be a durable building material, but I've struggled with how to make nice end caps and power/monitoring connection hook-ups. Enter the 3D plastic printer! This build thread will document, hopefully, the process of bringing this concept to reality.
I'll be starting with standard 4" PVC fence posts I get from Home Depot. They measure approx 95mm inside diameter which gives ample clearance to place the 5s 8000mah packs I've been using inside with room for padding and wiring. At this point in time, I'm thinking I'll be using just clean cut, square ends as opposed to the angle cuts I've used on the Kona triangle build.
The tubes:
Moving on to the end cap design, it's been a bit of trial and error. I started with the bottom end cap since I plan for this one to be boring and flat with no connectors. Here's the sketchup file:
To test fit, I printed the different components to fine tune fitment and save time and plastic. The entire bottom cap takes about 1.5 hours to print. I first designed the inner support structure and printed it to make sure it would fit snugly inside the PVC tube. After this print, I simplified the bracing from 8 to 4 cross pieces- it's plenty strong.
Then I needed to check that the outer most aspect of the end cap would sit flush with the outside diameter of the PVC tube.
Once I was satisfied with the dimensions, I printed the full bottom end cap.
Now on to the slightly more complicated top cap. Here's the proposed sketchup design:
Here's a connector hole test print. I use 4 anderson connectors (2x2 stack of postive and negative) which allow me to connect this pack as 10s2p or 20s1p by changing the external connection from parallel to series. The trapezoidal hole is for a DB25 connector I use to connect the balance leads.
View attachment 1
I spent too much time tinkering with the anderson connector portion of this end cap- I should have just made it so I glue it in place. But that's the fun of playing with the 3d printer; you can make it as complicated as your imagination/skill level allows. This is the first iteration I tried. I was trying to print the tight tolerance 0.5mm grooves to slide the anderson housing into, but this is not possible with my home built rig- the edges are just a little too round to make the tight friction fit necessary.
The little nubs from the prior design were effective, however, so I used that as the main "keeper" portion of the the current design. Here's the sketchup file:
The 4-pack anderson stack clicks nicely in place and then a zip tie will run around the outside (in the groove) to keep it secure as well as allow it to be replaced easily if necessary without printing another top cap.
The top cap is a 3+ hour print.
I'll be starting with standard 4" PVC fence posts I get from Home Depot. They measure approx 95mm inside diameter which gives ample clearance to place the 5s 8000mah packs I've been using inside with room for padding and wiring. At this point in time, I'm thinking I'll be using just clean cut, square ends as opposed to the angle cuts I've used on the Kona triangle build.
The tubes:
Moving on to the end cap design, it's been a bit of trial and error. I started with the bottom end cap since I plan for this one to be boring and flat with no connectors. Here's the sketchup file:
To test fit, I printed the different components to fine tune fitment and save time and plastic. The entire bottom cap takes about 1.5 hours to print. I first designed the inner support structure and printed it to make sure it would fit snugly inside the PVC tube. After this print, I simplified the bracing from 8 to 4 cross pieces- it's plenty strong.
Then I needed to check that the outer most aspect of the end cap would sit flush with the outside diameter of the PVC tube.
Once I was satisfied with the dimensions, I printed the full bottom end cap.
Now on to the slightly more complicated top cap. Here's the proposed sketchup design:
Here's a connector hole test print. I use 4 anderson connectors (2x2 stack of postive and negative) which allow me to connect this pack as 10s2p or 20s1p by changing the external connection from parallel to series. The trapezoidal hole is for a DB25 connector I use to connect the balance leads.
View attachment 1
I spent too much time tinkering with the anderson connector portion of this end cap- I should have just made it so I glue it in place. But that's the fun of playing with the 3d printer; you can make it as complicated as your imagination/skill level allows. This is the first iteration I tried. I was trying to print the tight tolerance 0.5mm grooves to slide the anderson housing into, but this is not possible with my home built rig- the edges are just a little too round to make the tight friction fit necessary.
The little nubs from the prior design were effective, however, so I used that as the main "keeper" portion of the the current design. Here's the sketchup file:
The 4-pack anderson stack clicks nicely in place and then a zip tie will run around the outside (in the groove) to keep it secure as well as allow it to be replaced easily if necessary without printing another top cap.
The top cap is a 3+ hour print.
- but it held and felt solid).
) in a side-by-side configuration. The four pack tube is just long enough to be inconvenient; it won't fit in any normal MTB triangle and it looks a bit out of place being carried on the back. More to come when I have pics of my progress.
) where these was going to end up as a backpack!
