[lazide]

Fuses are not items that should be replaced normally - they are self-destroying emergency protections for the electrical system.

If it is protecting that end users can plug arbitrary loads into, that is one thing - but this doesn’t sound like that?

Why did that fuse blow? Because if that is not addressed, it’s likely to just blow again.

[jacquesm]

I think the people that replace fuses are aware of the potential issues around them. The article - which I'm sure you've read so don't take this as commentary on your comment - details that in other electric vehicles, for instance Tesla this is handled quite differently:

"While Tesla’s pyrofuse costs €11 and the BMS reset is around 50€, allowing the car to be safely restored, BMW’s approach borders on illogical engineering, with no benefit to safety, no benefit to anti-theft protection — the only outcome is the generation of billable labour hours and massive amounts of needless electronic/lithium waste."

It's not a choice between 'ridiculously inaccessible with the potential to create more damage than your car is worth' and 'push to reset'. There are many options in between, some of which would be a happy medium between the two that protect both safety, the environment and the customers' wallet. Which BMW's solution clearly isn't.

[bradfa]

This fuse blows because a crash was detected and it is to protect the people inside the car and rescuers. The article argument is that it can blow even for small crashes where no damage to the battery occurs but rehabilitating the vehicle still incurs an outrageous cost. This is not a simple over current protection fuse.

$1000 for the module with the fuse seems ok to me. Another $3000 to link the module to the vehicle is the outrageous part.

[jinzo]

They are not only linking it to the vehicle, they are doing a LOT of other checks on the battery - that it's not damaged in non-obvious ways. For that you need trained people (it's really high voltage and amperage stuff), tooling AND you really need to be sure you guarantee everything is OK.

Even the basic mechanical disconnect and lowering of the battery is far from simple (and requires A LOT more expensive tools than changing a wet belt - not because they are greedy, but because a lift that can lower such hevy battery costs a lot of money, mostly in materials), and that's not even opening it, making sure you don't get electrocuted when you work on it ect.

[20after4]

The lift costs about as much as one of their repair bills. That can hardly justify the cost.

[taneq]

Yep, might be there was a known issue that was addressed, at which put in a new one. But just replacing a fuse (or, simultaneously worse and better, just resetting a breaker) without further investigation is just kicking a very spicy can down the road.

I had a doozy of a trip issue on one project, a motor would occasionally (not always, no real pattern, hot/cold/etc. didn’t matter) trip the breaker, requiring a sparky to come out and open up the panel to reset it. We tried a bunch of things, megger-ing the motor, testing peak startup current on each phase with a fancy meter, checking phase-to-neutral current (Larger than you’d think! But this was normal, apparently.)

Everything was normal. In the end all we could think something was weird about the contactor. They took it out (I was off site at the time) and took it down to the substation to test it out.

With three phases connected to the contactor (and nothing connected on the other side) they energised the coil, and with an almighty bang it tripped the main incomer and took the entire sub offline.

Turns out there was a manufacturing defect in the contactor and sometimes for a millisecond, if the phase of the moon was right, it dead shorted two phases.

So there, even when you know everything, you don’t know everything.

[11mariom]

> Fuses are not items that should be replaced normally - they are self-destroying emergency protections for the electrical system.

Next time when the fuse switch in my home I'll buy new home. I shouldn't normally switch on auto-fuse again!

Fuse blows, so you know something went wrong, you check corresponding part, fix it, and enable/change fuse. Nothing special. In home perspective - it could be plugging too many energy needy receivers into one outlet.

[lazide]

That is literally exactly what I’m saying.

In that situation, if you bypassed the fuse, or just kept replacing them without figuring out why it blew (too much load on a specific circuit), you very well might burn your house down by catching the wiring inside your walls on fire.

If it’s something that it is easy to connect loads too, then that is probably not super unusual and easy to fix, because people do that all the time, and you know what is happening and how to fix it. But you do need to fix it.

If it isn’t, then that is very concerning, because something caused that overload, and without that fuse your wires would have caught on fire instead of the fuse blowing. Inside your walls.

Either way, fuses are an emergency measure to stop the wires from destroying themselves from overload. They are destroyed in the process of saving your wires.

And if you are doing this all the time? You’ve got a very big problem brewing.

[torginus]

Ladies and gentlemen - behold the perfect consumer

[potato3732842]

Then why name it a goddamn fuse then?

[prepend]

The article gave examples for why the fuse blows - it falsely thinks the vehicle was in an accident and trips. Hitting a pothole or a rabbit.

It is unlikely to blow again under normal use.

[kristjank]

Fuses are necessary on any electrical system, and especially in a car, which is an electrical shitshow (floating ground, high-voltage and high-frequency interference), fuses blow all the time. Granted, usually on a well-maintained and new car it happens very rarely, but saying that it's a catastrophic and concerning event is dumb.

[jinzo]

This is a pyrofuse, it does not blow with overcurrent as regular fuse, but blows in the same way airbags blow - when detecting a crash. We can debate if they blow too quick, but if you are designing this system - where and truly lives can be in danger, you would probably err on the side of caution too.

[LorenPechtel]

The problem is not that the pyrofuse blows. Safer to be paranoid when it's the the battery pack. The insanity is what it takes to replace it, including throwing away perfectly good parts because of the anti-theft protections.

[idiotsecant]

Pyrofuse will definitely blow on overcurrent.

[jacquesm]

Usually not by itself though, and if it does that makes it a hybrid fuse, one that has both a pyrotechnical disconnector and a thermal/overcurrent one.

[lazide]

What sort of cars do you drive?

I’ve never had a fuse blow on a car less than 20 years old, and then it was due to shorts due to damaged insulation and bad grounds due to corrosion, which are legit problems that need to be corrected.

Also, unlike breakers, fuses are generally immune to issues with HF interference and the like - they work through basic thermoelectric effects which iron out all but the most extreme issues. If you’re moving multiple amps in a situation described as ‘RF’, or ‘high frequency’ in a DC system that’s not just noise!

That’s a real problem that needs fixing!

Not fixing the underlying problem behind a blown fuse (or constantly tripping breaker) is how your car (or house or whatever) burns to the ground.

Or you have a Lucas, in which case my condolences.

[kristjank]

I'll grant you that, I had a lot of beaters. A typical thing was that a lock solenoid pulled too much current in cold weather and consistently blew the central locking fuse.