Not all knowing, but this is one area where I work on the other side of the fence. When you design electronics for an automotive environment you do so knowing that you're working with an extremely variable environment, where lots of things go wrong with the supply on a regular basis.
Electronics in cars aren't "sensitive". They're hardened. They have to deal with operating temperature swings of hundreds of degrees over the course of a few minutes. Constantly variable voltages. High frequency noise from the ignition system. Batteries go bad. Connections go bad. Diodes go bad. Voltage regulators go bad. If cars suffered damage to the electronics every time something like that happened it would cost the manufacturers a FORTUNE in warranty costs. A car will take a direct lightning strike and keep running!
You know what you've been taught, and that's fine, but I know the design requirements that have to be met for an electronic module to be approved for use on a car because I've been working in that arena for the last 10 years. You can throw out all the courses you like, but I can guarantee you that none of those guys have any damned idea what's behind the design process for the electronics and the requirements that have to be met.
So settle down and stop ranting because someone doesn't subscribe to the same bunch of old mechanics tales that are repeated with no basis all over the internet. You can continue to repeat that crap, or you can stop and think about if for a few minutes and you'll know I'm telling you the truth.
The notion that stuff on a car is going to start blowing up because you disconnect the battery is just absurd.
First off, I never said things would blow up, but if you want me to tell you what operation has the highest degree of potential blow up in the engine bay, it's disconnecting a battery. Surely you know that.
Second of all, you think disconnecting the battery, while a car is running, is less of an old mechanics tale, than me saying it's not the right thing to do? Well I disagree, and that's not just because I was taught something, it's because I did work on cars, most of my life. And I still do, shops call me to solve their electrical gremlins, and I solve them. The fact that you know more about resistors than I do does not mean you have more practical experience repairing them.
I agree that mfg's try very hard to mitigate failures, but that doesn't mean abuse is the right thing to do. BMW doesn't even want you to jump start their cars. And I've had failures with reverse polarity, bad grounds, and even welding. All preventable!
I've never had a failure due to disconnecting the battery while the vehicle is running. Know why? Because I've never done it, and I never will.
My post said "please don't do that", you made your electrical engineer statement, who is really ranting?
We've disagreed before, when you were an electrical engineer designing solar inverters, we'll disagree again, but I won't quote you ever again, since what I say is "crap" according to you. I'll keep my opinion of what you say to myself.
Good day sir
