I designed a simple 3D-printed solderless battery pack design.

Mazzz

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Jan 20, 2019
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Hello there, this is my first post but I've been interested in building battery packs from used batteries for quite a while. I wasn't happy with the current solutions of spotwelding where expensive machines are required, or soldering which damages cells.
Another major problem is that they are pretty permanent. When a cell dies then the whole battery back has to be dissasembled and reassembled, and it is pretty hard to isolate which battery is under preforming.

I've designed a simple 3-d printed enclosure that is made up of only plastic and nickel strips. Here are some pictures:


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Basically two nickel strips are inserted into the bottom and the top of the enclosure and then screwed on with the plastic cap to keep them in contact with the battery, simple. At any point you can remove the nickel strip to access the cells and get them out!

Please suggest any improvement or any possible issues that you can see. If people want to use this design themselves I am happy toupload the 3D file.
 
Interesting idea and design.

The only negative side is, that if a cell in the middle of the pack needs replacement, you have to undo every holder cap in the row to get that one out.

Perhaps a revision would be to make it so the strip runs along the side of the holder, and an L shaped tab is in the holder making contact between the bus strip and the cell(?)
 
Korishan said:
Interesting idea and design.

The only negative side is, that if a cell in the middle of the pack needs replacement, you have to undo every holder cap in the row to get that one out.

Perhaps a revision would be to make it so the strip runs along the side of the holder, and an L shaped tab is in the holder making contact between the bus strip and the cell(?)

Nice idea, havent thought of that actually. That would probably be great in applications where batteries would need to be swapped reguarly like a mass charger or when the nickel strips on either side aren't able to move. I'm trying to build an Ebike so cells will rarely be changed and I'm trying make it as simple as possible.
 
Nice,
The thing that I have noticed about similar 3D printed designs is that they trap a lot of heat.
But most Ebikes batteries are made that way because of the environment they are in.

Another mod avoiding using the L shape or threading the nickle strip.... run the strip directly across as you currently are but cut out the threading so when the caps are removed the nickle strip lifts right out. You might have to place more plastic for the threading that is left as re-enforcement.
 
Bubba said:
Nice,
The thing that I have noticed about similar 3D printed designs is that they trap a lot of heat.
But most Ebikes batteries are made that way because of the environment they are in.

Another mod avoiding using the L shape or threading the nickle strip.... run the strip directly across as you currently are but cut out the threading so when the caps are removed the nickle strip lifts right out. You might have to place more plastic for the threading that is left as re-enforcement.

That too is a pretty neat idea. I might do just that accually. At first I planed to put holes in the end of the nickel strip and bolt it down to connect strips instead of soldering. Now I'm not really sure haha. I'll try printing the design and see if its strong enough
 
Although this design may not be perfect for all applications, do not be deterred by critics who talk it down. This is a good design that is very useful for many people. Well done!
 
This is pretty cool, any plans to release the STL?
I think it would be really great for smaller packs like 1s or 2s!
 
Such a solution can be good in many situations, but it will not work on things that have exact space requirements (like many power tools packs). The plastic tube and a spring would generally suffice for many projects. Good thing you have the printer to create them.
 
That is a really grate idea. Perhaps you can solder cell-level-fuses to the nicel-strip and then to bus-bars? that way you can de-solder the fuse in order to extract the cell. I would also consider to make the design "connectable" so you can stack them up and have a sturdy connection. For a better ventilation, you can add some slots. I know it depends on the cells, the environment and the use-case but I would not like my cells to heat up when in use. I have some 1300mAh 45C 12V Lipos here, that will get warm during use, but I do not expect them to live more than 500 cycles at all.
I am definitely interested in the .STL!
 
There are several parallel technologies that deal with similar packaging constrants of positioning a group of Cylinders as close together as possible. If we start to list these out we may be able to steal some good ideas

For example in this design the driver for maximum density is the cap since cap is larger then the cylinder base

How would a spin and lock work were a rotation of 45 degrees is all that is need to lock. This could open up room for buss bar to drop in. You can also package the features for locking in the available dead zones at 2 5 7 and 9 ocklock 5 . Think about the large head size of product we can not name. Why should head size drive our design.
 
Or you know, just put it a small nickel plated copper strip instead.

That would be much simpler.
 
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