Hacker News Reader

Comment by BenjiWiebe | Hacker News Reader

Your car will come to a stop on it's own when there's no electrical power left. ICE cars can run with a dead battery only as long as the alternator is working and producing electrical power.

When your alternator dies, the car runs until the battery is dead, and then the whole car stops.

Much older vehicles could run without electrical power but now with electronically-controlled engines you've gotta have electrical power.

View on HN

> Your car will come to a stop on it's own when there's no electrical power left.

Newton's laws would disagree. "An object in motions stays in motion..."

GP is asking "what happens if the alternator dies, and the battery runs flat while you're driving?" This may sound like an outlandish scenario, but my uncle had something similar happen to him not too long ago.

And not all cars can run solely off the alternator when the battery is dead. Several years ago, my mom's Grand Caravan wouldn't start when she was out. She called AAA, and they jumped the car, and it started just fine. But as soon as the AAA guys disconnected their jumper pack, the van died. They tried it several times and weren't able to get it to stay running.

If your brakes require a fully-functional electrical system to apply any force at all, that seems like an unacceptable failure scenario.

To be a real emergency, it would have to also happen when you were planning on braking very soon. At least with my driving patterns most of the time I'm driving I'd be able to safely coast to the shoulder. The failure would have to coincide with a stoplight turning red or something. Hmmm, even the horn wouldn't be working without electrical power...

All older cars the brakes work 100% of the time, whether or not you have gas or electrical.

How old are we talking about here? If you have power brakes then when the engine shuts off the brakes don't work at 100%. At that point you're needing to push the hydraulic fluid without assistance and you'll find it's really not easy to stop. Also no power steering. A windy mountain road is not a good place to be...

At that point, engine brake with the clutch.

Unless you're driving an automatic.

I'm pretty sure my old car's owner's manual specifically said that engine braking effect can be increased by downshifting the automatic gearbox to a lower gear in the manual mode. Current car's owner's manual says to release the accelerator when approaching red lights to "take advantage of engine braking" and since it's a hybrid, it also does regen.

There's also quite a few different ways to make an automatic gearbox, such as double-clutch gearboxes.

That's what my car's manual said, too. But the "lower gear" in Drive mode was electronic. It didn't have a dedicated "low" or "2" or whatever position. On my dad's Toyota it's even worse, the "gearshift" is fully electronic.

There's always the handbrake.

Let’s face it though

Without ABS the ability for a layperson to brake is greatly diminished

People aren’t going to remember to pump the brakes in an emergency, heck most people don’t even know rhythmically pumping the brakes is a thing

You should never pump your brakes, even if you have no ABS. What you should instead be doing is "threshold braking", so you should have as much brake pressure as you can without locking up the tires, and if you lock up, you release as much as you need until you're not locked up anymore. If you just pump the brakes in rhythm, you'll have longer a stopping distance as you're just alternating between no braking and too much braking.

Thankfully most cars on the road at this point are going to have ABS, which just allows you to stand on the brake pedal in an emergency.

> Without ABS the ability for a layperson to brake is greatly diminished

> People aren’t going to remember to pump the brakes in an emergency, heck most people don’t even know rhythmically pumping the brakes is a thing

I don't think looking at the extremes is the right approach here.

I've brought my car to a stop thousands of times, yet I've never once required the assistance of the ABS, in fact, I have no empirical evidence that it actually works at all.

Needing to brake and stop isn't an emergency situation, it's a very typical situation, and it would only become an emergency if you _can't_ stop.

If you happen to be having an emergency at the same time you lose electrical braking, you're shit out of luck.

Reply on news.ycombinator.com