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Comment by StillBored | Hacker News Reader

I think the larger concern should be fire safety. Normal 3d printer filaments don't have the fire retardants required by UL/etc for power electronics. I've experienced power supply and battery failures that were contained by their enclosures enough times in my life to take this very seriously. Had any of those cases been wrapped in common PLA/PTEG/ABS from a 3d printer, i'm sure it would have been much worse.

So, if your printing anything that has a likelyhood of catching fire you should probably be doing it with something like: https://www.3dxtech.com/flame-retardant-filaments/firewire-f... or just wrapping that part of the design in sheet metal.

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You also have to realize things like this have to take scale into consideration. No one is going to do mass manufacturing of battery and electronics enclosures with 3D printing, this is a prototyping and hobby level manufacturing system. So the odds of injury and damage are a lot less with this as you automatically self-select down to a tiny fraction of the market share, and only a tiny fraction yet of those will ever experience an explosive outcome from a battery.

Also I'm sure that most of this market violates someones IP so again, this ensures that this type of thing (custom making battery enclosures) will never reach a critical mass where worrying about the world burning down due to non-fireretardent plastics is something to be concerned about.

But if a person is very concerned about this issue then certainly there are options out there.

How does this flame retardant ABS work in the event of a lithium battery fire? Are there flame retardant PETG? Are they any better than just printing with normal filament and spraying flame retardant on it?

I've been hesitant to use lithium batteries in home robotics projects, but I can't find charging and power mux boards for NiMH, so that has been a huge blocker in making robots that charge and operate at the same time.

Also I wonder if it is possible to put mini pressurized CO2 balls inside the battery enclosure such that if a fire happens they explode and release CO2, putting out the fire?

I suspect to have the right answer you will need to read the relevant standards/cert and understand how it interacts with your design.

But the general theory as I understand it generally is not that the plastic may not burn, only that they are self extinguishing. V-0 like that filament means it will extinguish itself within a maximum of 10 seconds after the ignition source is removed.

Regular filament acts more like an accelerant, put a flame near it and it burns quite vigorously, and for a long time. Meaning anything near it that can burn will likely catch fire too.

> Also I wonder if it is possible to put mini pressurized CO2 balls inside the battery enclosure such that if a fire happens they explode and release CO2, putting out the fire?

No, that may momentarily put out the flames but as long as the thermal runaway condition is still present it will reignite. The only way to stop a battery fire, which is actually a metal fire, is to permanently suffocate it - usually by dumping heaps of salt, cement or salt on it which melts and so removes oxygen from the fault area - and then, at least for electric cars, to dump the car in a container full of water and keep it there until dismantling, so that the water acts as a thermal buffer to prevent reignition.

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