Danger in 3D printing over a lithium ion battery

  • So I bought a Lulzbot Mini a couple months ago and finally downloaded Ultimaker's version of Cura... Boy... have I been missing out...

    One feature Ultimaker Cura implemented that I've been looking for is a "pause at z-height" feature ("post-processing tool"). I'm building prototypes of an electronics device, and creating two pieces that snap together looks a lot worse than printing a single piece. If I could pause my print, insert my electronics, and continue printing, my device would look a lot more professional (even if it took longer to make).

    My one concern is the lithium ion battery. Right now I'm printing in TPU. With a heated bed of 40 degrees Celsius, and a heated extruder at 240 degrees Celsius, there seems to be a significant risk that the lithium ion battery reaches a temperature above 60 degrees Celsius (damaging the cell, causing a potential explosion). Granted, I am not sure what "60 degrees Celsius" actually means. It could mean only one part of the packaging needs to reach this temperature, or it could mean the entire LiPo's internal temperature would need to reach this. In either case, the numbers don't look good.

    On the other hand, the heated bed surely doesn't need to remain heated beyond the first few layers? Additionally, I can create a "roof" for the LiIon battery that I can slip it under, providing some insulative TPU before the rest of the device. I think the print would happen safely like this, but obviously, an explosion would be really really bad. Like it would probably burn my house down, and I would be asleep when it happened.

    Does anyone have any experience doing this?
    Is there a way to turn off the heated bed mid-print? I guess I can insert a g-code line during the pause? Will this affect the remainder of the print you think?
    Am I being paranoid? Can the extruder actually pass heat through a 1–2 mm of insulation and cause an explosion?
    Anyone know how heat travels from the initial, liquid print material through the rest of the structure?

    Any more advice or things I should consider before pursuing this?

    A more specific pause type might be helpful, if anyone knows of any.

    Is wrapping the battery into something heat dissipating an option? Usually putting a battery next to a heater is a big no-no. You don't want to be close when it goes wrong, neither does your house.

    I'm not sure why you'd embed the battery like this either. It sounds like your construction will make it non-removable.

    @Mast Because no electronics manufacturer does that.

    One further drawback to this method of printed your part is that you are only able to produce the part when you have internal components on hand. If you design the part so that it can be printed without the internal components you can have parts created even without the internal components and perhaps improve speed of creation of additional "devices" by having a supply of this part that you just draw from.

    True, but for one or two very nice prototypes it could be okay.

    freeze the battery before printing, and print the layers next to the battery as fast+thick as possible. you can set temp in gcode or manually over-ride on the front panel.

    I'm going to note that if you choose to go this route, look into how to put out battery fires. I believe water will just make it worse..

  • There is an option to directly insert extra commands at a specific Z height, no need to enter them manually.

    That said, it is a bad idea to turn off the heated bed while printing, because this will often detach the object from the bed completely (that's kind of the point of having the heated bed in the first place: better adhesion while printing, and easier removal afterwards).

    I wouldn't print over a battery to enclose it, not just because it is likely to damage the battery, but also to keep the battery exchangeable. Enclosing the rest of the design in a case is possible, but normally it is easier to print two separate parts that can be screwed together through a hole in the PCB.

    So, experience: it's not worth it usually.

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Content dated before 7/24/2021 11:53 AM