Comment by kristjank
10 hours ago
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.
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.
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.
Pyrofuse will definitely blow on overcurrent.
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.
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.
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.