The active fuse

[Matias]

Does anyone know what about that fuse costs 10k?

Tesla's profit.

 

[LetsGoFast]

So, it is all about precision. They're taking the old simple dumb fuse that blows at approximately 1300A within a few hundred ms of that limit being hit, and replacing it with a smart fuse that blows at exactly 1500A, within a defined +/- Amperage and time tolerance. With that precision in place, they can then push the limits more in other parts of the system..

Traditional fuses just aren't that precise. they have a certain tolerance which changes with ambient temperature and with age of the fuse (fuses fatigue with repeated exposure to current near their rated limits). Because blowing the fuse is problematic, you can't run right up to the rated limit on a regular basis.

 

[miimura]

Does anyone know what about that fuse costs 10k? And why is refitting it to a P85D only half as expensive as ordering it right from the factory? One should think it would be the other way round.

The $10k price includes not only the Smart Fuse, but also the Inconel Contactor. The rest is profit and the price is really derived from the perceived value of Ludicrous Mode, not the actual costs. The reduced pricing for retrofit is a promotion in appreciation of the early P85D buyers.

 

[Ingineer]

On the dual motor cars they add in 2 extra fuses outside the battery pack (under the rear seat). I suspect the E-Fuse(s) replace these, and there is still a conventional slow-blow thermal fuse in the pack as before.

 

[wk057]

On the dual motor cars they add in 2 extra fuses outside the battery pack (under the rear seat). I suspect the E-Fuse(s) replace these, and there is still a conventional slow-blow thermal fuse in the pack as before.

Hmm... this doesn't fit with the info I've gotten so far that points to the main pack fuse and the contactors being the items up for replacement.

 

[EarlyAdopter]

Does anyone know what about that fuse costs 10k?

NRE + low volume custom part.

In time we may find these become standard parts for all packs.

 

[RDoc]

I imagine the computer hardware and software in this active fuse is pretty simple. It's basically going to be running a tiny infinite loop going: while(forever) { if(current > 1500A) explode(); }.

At that level it's certainly machine language and the first literal implementation of the HCF instruction I'm aware of.

 

[sorka]

I'm still trying to figure this out. On the face, Elon says it the fuse moves from 1300 to 1500 amps. But nowhere near 1300 amps is passing through the current fuse. Will it it also be that the e-fuse maintains the same margin or are we talking about a 1300 amp fuse that has to have a very high margin vs a 1500 amp fuse which can be run at *exactly* 1500 amps. If the latter, then the increase in KW (hence hp) would be more than 200 amps...maybe a lot more.