Tesla 4680 Structural Pack Cement Like Foam

Munro and Associates have finally been able to safely remove the top cover of the Tesla 4680 battery pack from a Texas produced Model Y.

It reveals a cement like foam. The structural strength of the battery pack is very high.

The 4680 structural batteries and pack reduce weight of the vehicle by having the battery and its structure replace steel structures.

11 thoughts on “Tesla 4680 Structural Pack Cement Like Foam”

  1. Forget about flammability, focus on the toxicity of fumes created when exposed to high temps. Far more dangerous than fire

    • Foams, being mostly air, are deformable. Foams used in torsion box designs like this are not subject to point loads. The purpose of the foam is to prevent the skins from getting closer together or further apart as they would under torsion (twisting) or buckling (folding) of the pack. In both of those cases, the load is spread across the entire area of the foam and so a high PSI foam is unnecessary. It’s far more important that it is strongly adhered to both skins and completely fill the space between them.

  2. I’m using used Nissan Leaf batteries in my robotics hobby. I think it’s pretty clear that there’s no real prospect of switching to Tesla batteries.

    I guess that’s not really a slam against them, except from the perspective of end of life reuse.

  3. I wonder how flammable it is.

    Depending on composition, it could help with fire suppression or it could make fires worse.

    • It’s just an in situ foamed polyurethane.
      Dense – sure – but calling it cement is a stretch.

      As for flammability – it most likely ‘combustible, but does not sustain fire’ type material, however depending on additives you can make it nearly non-flammable (so it would just char, without producing flame).

    • Composition really doesn’t matter, so long as it is not an oxidizer.

      With the foam, the pack is effectively airtight meaning no oxygen or, more importantly with Li, water will reach the potential sources of ignition so the likelihood of fire is actually quite low.

      And with the torsion box design placed low in the structure makes a breach of the pack in typical accident scenarios very unlikely. Obviously something puncturing one of the skins is possible, but I wager accidents that could result in a puncture are a small minority.

      • Have you ever heard of an ICE vehicles Oil Sump being punctured by road debris? I will concede it is rare but usually happens at highway speeds and causes big problems for the engine. If the same were to happen to a structural battery you can pretty much kiss your new Tesla/EV good-bye. I’m not sure what safety systems are incorporated into the vehicle to alert the occupants they have a battery fire and must get out immediately but at least with an ICE vehicle you’re only repairing or replacing the engine in such an event. I personally have seen the damage caused by a suspension component on the road from another vehicle puncturing the sump of an engine. The driver did not see it and could not avoid it. I’m not Pro-ICE or Pro-EV I do believe there are suitable applications for both platforms and I agree City commuters should definitely be driving EV’s or Catch Electrified Public Transport. Here in Australia the electric charging network is very much in its infancy.

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