To me the interesting part of this was how social media is sometimes absolutely amazing. Woz idly poses a question about the fuses in his car and has an engineer from the manufacturer write a detailed response in short order. That is incredible.
“Why does a car like the Tesla still have old-style fuses?”
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Re: “Why does a car like the Tesla still have old-style fuses?”
#22I've replaced most of the easily blown fuses in my car (accessories, etc.) with PTCs. Now I joke that turning the car off and then on again fixes the problem. However, I wouldn't do that with a vital system (starter motor, etc.) because a blown fuse generally informs you of a deeper problem, rather than being the problem itself.
http://en.wikipedia.org/wiki/Resettable_fuse They make these in automotive format, or you can go to Digikey, get a PTC of the current you like, and solder it onto a blown fuse.
PTCs have the advantage of being straight replacement, and if you want, you can add a Hall sensor to see if current is flowing without creating paths to ground or other problems.
Anyone knows how to add this answer to Woz's thread? The "awesome power of social networks" isn't that awesome, since I can't answer on the thread linked...
Re: “Why does a car like the Tesla still have old-style fuses?”
#23Well, amateur experimental aircraft have something like this available: http://verticalpower.com/ - but there's a lot of negative reactions to this kind of technology, because it introduces new failure modes where none previously existed before. But I think something that people forget is that generally, fuses are there to protect wiring and fixtures (switches, connectors, etc) from fire. Preventing the device on the…
On the point about building wiring codes, here in the UK we actually do have both central fuses/circuit-breakers and load specific fuses in the plug for each device.
After reading your comment it did make me wonder as I plugged our coffee machine this morning how the design substantial chunk of plastic and metal I was holding was influenced by the aftermath of WW2.
Re: “Why does a car like the Tesla still have old-style fuses?”
#24To me the interesting part of this was how social media is sometimes absolutely amazing. Woz idly poses a question about the fuses in his car and has an engineer from the manufacturer write a detailed response in short order. That is incredible.
That's less social media and more Woz asking a question.
Or rather, this is the internet at work, not social media. The only thing social media has done is reduce the time between question and answer. And that's impressive, but it's not the fundamental shift the internet itself was.
Re: “Why does a car like the Tesla still have old-style fuses?”
#25Because cars are not expected, under normal circumstances, to experience abnormal amounts of current on any given circuit. Unlike a house, where you can easily plug in something into the outlet that can overwhelm the circuit, in a car each circuit is designed specifically for a given maximum load.
When you blow a circuit in a house, you have most likely massed up and plugged too many things into one outlet, or your device is drawing too much power. You learn from your mistake, unplug the device, and reset the circuit. If a car blows a circuit, then there is something seriously wrong with some component of the car or the wiring. You don't want the user to be able to reset the circuit, you want someone who knows what they are doing to figure our what went wrong.
I fix all of my own cars, and never once have I ever had a blow fuse "just because." There always was an underlining cause which needed to be addressed. Except once, when a 10A fuse was used in a circuit that required a 25A fuse, on a window motor.
So, basically, in a well functioning and well designed car a fuse will not fail just because. So why bother replacing a part that costs less then a cent with a part that costs several dollars. I hate this attitude, just because something CAN be complex, does NOT mean it has to be complex.
Take car modules for instance. It used to be that back in the day (the 90s) your headlights were operated by a mechanical relay. This relay was expected to fail at some point (though they very rarely actually did fail) and as a result this relay was installed in an easily accessible place. If it did fail, it would cost $10-15 to replace it plus 5 minutes of labor.
New cars nowadays have solid state switching modules to operate headlights, and everything else in your car. These components are not expected to fail, even though they often do. Don't believe me, talk to any mechanic. However, because they are not expected to fail, they are often installed deep inside the car. So, now, if your headlight module fails, it costs $400 in parts, and several hours of labor to fix the same problem. Progress?
Stop making things needlessly complicated. Blade fuses are a fine solution to a problem.
Re: “Why does a car like the Tesla still have old-style fuses?”
#26Because cars are not expected, under normal circumstances, to experience abnormal amounts of current on any given circuit. Unlike a house, where you can easily plug in something into the outlet that can overwhelm the circuit, in a car each circuit is designed specifically for a given maximum load. When you blow a circuit in a house, you have most likely massed up and plugged too many things into one outlet, or your d…
Progress?
Yes. For the companies selling the parts and the repair services.
Re: “Why does a car like the Tesla still have old-style fuses?”
#27Well, amateur experimental aircraft have something like this available: http://verticalpower.com/ - but there's a lot of negative reactions to this kind of technology, because it introduces new failure modes where none previously existed before. But I think something that people forget is that generally, fuses are there to protect wiring and fixtures (switches, connectors, etc) from fire. Preventing the device on the…
On the point about building wiring codes, here in the UK we actually do have both central fuses/circuit-breakers and load specific fuses in the plug for each device. After reading your comment it did make me wonder as I plugged our coffee machine this morning how the design substantial chunk of plastic and metal I was holding was influenced by the aftermath of WW2.
The British plug is a marvel of good engineering. Other countries look on it with envy (except possibly Australia, which has a similar design of its own, IIRC).
Now of course it was "overengineered" by the standards of the time, to compensate for our ludicrous, dangerous, and still-legally-required "ring main" system, which as you say was due to aftermath-of-WW2 copper shortages. But the plug design is the part we got right.
Re: “Why does a car like the Tesla still have old-style fuses?”
#28Earlier quoted context omitted.
Having a fail-safe functionality (vs ... fail-deadly, I guess, with no fuse) is critically important (far more than just being a good idea), but there's no reason it can't be a circuit breaker with feedback to the computer system. Self-resetting would probably be a bad idea (if there's a short, you really do want it to stay off), and even having computer control of it would be questionable (although if the control sy…
On top of this, mechanical circuit breakers would have vibration issues when mounted in a moving vehicle. If it's too vibration-resistant, it might not trigger under overcurrent conditions. If it's not vibration-resistant enough, the car flakily breaks on bumpy roads. Solid-state circuit breakers do exist, and would solve the vibration problem, but some quick Googling didn't turn up anything that looked at all inexpe…
Sounds plausible, but if you Google "automotive circuit breaker" you'll find they exist and are quite cheap.
Re: “Why does a car like the Tesla still have old-style fuses?”
#29"What's the problem?"
"Car won't start."
"Did you try restarting it?"
Re: “Why does a car like the Tesla still have old-style fuses?”
#30Earlier quoted context omitted.
On the point about building wiring codes, here in the UK we actually do have both central fuses/circuit-breakers and load specific fuses in the plug for each device. After reading your comment it did make me wonder as I plugged our coffee machine this morning how the design substantial chunk of plastic and metal I was holding was influenced by the aftermath of WW2.
The British plug is a marvel of good engineering. Other countries look on it with envy (except possibly Australia, which has a similar design of its own, IIRC). Now of course it was "overengineered" by the standards of the time, to compensate for our ludicrous, dangerous, and still-legally-required "ring main" system, which as you say was due to aftermath-of-WW2 copper shortages. But the plug design is the part we go…
Australian plugs are good, but have the live pins at the top (so for example a dropped coin will balance across them and short when the plug is pulled out), the plug doesn’t have its own fuse and the socket isn’t shuttered with no plug inserted.