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Comment by giarc | Hacker News Reader

>It will even do things like full field the alternator up to 18+ volts to slam the windows shut super fast in the event of a rollover.

I imagine this breaks the window mechanisms. However, you've been in a rollover, probably doesn't matter anymore.

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How is this of benefit? All I can see it doing is chopping off my arm if I've got it hanging outside the window.

If it prevents a child from being ejected, it will likely save their life.

How does a secured child get ejected from a vehicle? Sorry, that just doesn't compute..

E.g. my six year old is in one of these https://www.britax.com.au/car-seats/britax-safe-n-sound-enco...

childen go through glass. Its about keeping arms restrained.

As someone who frequently drives with my arm out the window, that would certainly be concerning. I can see some considerable safety benefits to containing unrestrained people in the vehicle (rollovers tend to result in ejections, which have a high mortality rate), but at least from a management perspective, I'd much rather let a negligent person be ejected 50 times than keep 49 of them in the vehicle and have 1 sue us because we cut their arm off.

As long as their sensors correctly identify a rollover vs. another kind of accident, I think it's an acceptable risk. If you're in a rollover situation you're likely to have both hands on the wheel already. If your arm is out the window during the rollover it's not likely to fare well anyway.

Which hand signal (brake, left, right) do you most often give when having your arm out the window? Do you mean it, and follow through, or is this the old-fashioned equivalent of leaving your turn signal on?

Note: hand signals are still legal, still tested on driver exams, and (as I saw a few weeks ago) still actually used for real.

Why isn't the middle finger an option?

Your concern should be for the safety of your customers, not for whether a measure that drastically increases safety might lead to a suit in rare cases.

If your arm gets flung out the window when that side of the car is facing up then it could get crushed when that side rolls over.

If you're in a rollover you won't have great control over your arms in the first place, so if your windows are open there's a good chance they'll be going out the window at some point. If you watch professional drivers in accidents, they attempt to cross their arms across their chest to keep them from flopping around.

If your arm is hanging outside the window and the vehicle is actively rolling, you're likely going to lose that arm.

Otherwise, based on all the other logic described, the decision to roll the windows up probably takes into account if there's an obstruction (just like auto-up windows do).

I'm not sure of the official reason, but I'd imagine it prevents ejections (or worse, partial ejections) from the vehicle.

I was the first person on the scene of a rollover where a woman was pinned underneath the car (fortunately only suffering broken bones) because she was partially ejected through the open window.

After extensive testing it was found that a clean amputation provides a quicker recovery than a degloved, torn up limb. There were more amputations that would be ideal, but net morbidity was reduced.

Source or sarcasm tag. Needs one or the other.

Come on, it's completely obvious that it's the second.

It will help keep your head from bobbing outside the vehicle as it rolls, preventing your death from a crushed skull.

Edited to add:

"partial ejection" are the magic google words. Here's an example:

"It was found that, in standard impact tests on high containment barriers, partial ejection of the head through the side windows occurs systematically"

from: https://trid.trb.org/view.aspx?id=750825

"Keep your arms and legs inside the vehicle at all times."

It sounds like it also may cause damage to other electronic components. They essentially switch the alternator into different mode that doesn't limit the output voltage in order to generate as much energy as possible.

I can't imagine them running a separate wire in the harness only for this one feature. It makes more sense to simply increase the voltage of the 'mains' 12V power inside the car, dump as much energy into it as possible, and design all critical components to handle the event gracefully. Sacrificing the less important electronics sounds like a viable option during a rollover event.

Automotive components are already designed to be very robust to input voltage transients.

Here's an interesting paper on the conditions automotive electronics are exposed to, including very high voltages during a load dump: http://www.ti.com/lit/an/snva681a/snva681a.pdf

Anybody that's accidentally dumped a capacitor into the car's electrical system when trying to install a subwoofer can attest to this. I was genuinely shocked anything worked in my car when I did it.

Motor & gear mechanisms usually have a lifetime that decreases at something like voltage^3. So you can double the voltage and get 1/8 the life. Since they have to be rated for thousands of cycles normally, you can overpower them a lot for a single cycle.

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