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Comment by Workaccount2 | Hacker News Reader

The author did a great job actually building the project, doing a layout and custom design rather than just stitching together off the shelf modules. Good work.

That being said, in 20 years of riding motorcycles and being an ATGATT (all the gear, all the time) kind of rider, I'm mixed on the need for this. It's something I have thought about doing with a direct hardwire to the throttle, but I can't come up with a situation where I genuinely think it will stop a crash. Maybe if someone is tailgating you, but you should be readily letting them pass rather than relying on their reaction skills anyway. Anything that is sudden and requires a large -dv/dt, you are going to hit your brakes. Engine braking alone is usually used in situations where the road/conditions dictates it, so other drivers are naturally slowing down too.

But I suppose it is also an "it can only help" type product.

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EV's with regen braking and manual transmission vehicles are in the same boat: unless they light up when slowing, following drivers will be surprised. The bare standard IMO for all vehicles should not be to light up when brakes are applied but instead any time the vehicle begins decelerating. Adding flashing for a strong stop ~~ >0.75g would be a bonus. Given all the sensors and compute hardware on vehicles -- even bikes -- these days it should just be a software touch.

The Technology Connections YT guy has a whole piece analyzing tail lights and I agree with him.

> Adding flashing for a strong stop ~~ >0.75g would be a bonus.

Is that a good idea? A flashing brake light could appear as if the brake was let go, which is the exact opposite of the message you would want to send in that case.

Or maybe we are talking about flashing between two different illuminated states?

Hard braking on modern cars activate the hazards lights, which are the blinkers.

Quick flashing or high/low would be the way, but quick flashing is very attention getting (with led)

It’s a common (mandatory?) feature in Europe. Brake lights flash under very hard / emergency brake conditions. The flashing is very rapid, definitely gets your attention, and couldn’t be confused for “letting go” of the brake.

For cars at last I thought it were the warning lights that were going off. Mostly because this is a common way to inform others that there are problems ahead (and a bed to quickly brake)

Regarding EVs: That's already implemented that way. Once EVs start braking more than "expected from roll resistance" the braking lights come on.

I think there were also bugs on some Hyundais where they wouldn't stop or start or whatever, but I think that was sorted. With my Skoda I can see the braking lights go on when I change a higher regeneration step.

You’d only be surprised if you were absolutely on someones ass. Engine braking is not quite that effective.

In fact this will make traffic worse due to stop n go effect from brakelights triggering more brakelights instead of coasting.

For what it's worth, I've driven a manual for the past 25 years in the US and I haven't noticed any significant increase in tailgated even when I decelerate. I'm definitely the kind of stick driver who avoids braking and pushes in the clutch and lets the vehicle cruise to a lower speed when possible.

Granted, it's also a red (small) pick-up truck, so pretty visible.

Many automatic transmission cars already turn on their brake lights when losing speed regardless of whether the brakes are pressed or whether not enough throttle is being applied to maintain speed.

I also believe some more recent cars turn on their hazards when brake speeds exceed a certain threshold (I still do that manually).

I guess those situations where you are engine braking and a non-tailgating driver doesn't realize he's closing to an unsafe distance. Then one of a couple of things could cause a collision from this preventably-dangerous situation.

Def not a daily event but not unheard of.

If you drive a manual in a hilly area, or a city with poorly-coordinated traffic lights, it can be an extremely frequent event.

Not that trying to shed tailgaters or trigger-happy brake lights are foolproof. A couple decades ago, my car was totaled by a rear-end collision. I was stopped and stuck in the traffic at a red light. The at-fault driver popped over a little hill with her nose stuck in a map - failing to notice me, the other vehicles, or the red light, in time.

Tbh I find my manual gearbox car not able to slow very hard at all with engine braking. However it's admittedly not a Diesel engine.

Having driven (and engine braked) both diesel and gas manuals - yes, a diesel is much better at slowing "very hard". Beware of doing that if someone is close or inattentive behind you.

With either one, any need-to-brake situation gets more complex - you need to decide "brake pedal, engine, or both?". But I'm not driving manuals because I want driving to be super-simple.

Interesting. I found my diesel Mercedes to not have much engine braking at all (which I attributed to the lack of a throttle plate or any throttling of airflow) as compared to similar size and weight gas cars (which have a throttle plate in the intake).

Supposedly, the engine controls in my VW diesel (90HP 4-cylinder "TDI" engine) cut off all fuel when the driver was engine breaking (no throttle, RPM's above current desired idle speed). Perhaps they made other adjustments. It could brake pretty hard that way.

I'd guess the engine controls in your Mercedes handled that situation rather differently, for "Mercedes customers will expect..." reasons.

I drove a manual with a 4.6l v8 as my daily driver for 8-10 years.

After taking a motorcycle safety course (in which they teach applying the brake to trigger the lights when engine braking to alert cars behind you )

I did some anecdotal testing / started triggering the brake lights when engine braking in the car. While not effective for everyone behind me, triggering the brake lights did seem to increase the distance people began to slow at, and also their following distance increased.

I was once rear ended, while I was completely stopped, with a train going by in front of me. Since it was a flat level surface I had let me foot off the brake.

I do wonder if I had still had the brake applied if the person would have noticed. (However, this is a poor example as the driver who rear ended me was an unlicensed 16 year old driving illegally ).

While on my motorcycle, I try to always trigger my brake lights. I will trigger them rapidly in scenarios where I have sufficient stopping distance but I would be doing a more aggressive stop in a car as the flashing does seem to get more attention.

I like a brake you can choose to tap without engaging proper brakes just to flash your lights backwards, instead of worrying about more smarts in the vehicle that can stop working or whatever.

In best cases this brake gives a bit of feedback when it engages the light but not yet engage the actual brake.

You are free to use this technique to signal "back off" whenever you're engine braking or before you brake or even when you're not even braking but don't like the tailgater

I’ve found this to be true of most cars- where you can very lightly touch the brake where the light will turn on before the actual brakes engage / engage in a noticeable way. It’s a great tool.

Especially important when engine braking down large hills, as I notice people don’t always seem to realize how rapidly they are approaching you if they don’t receive a braking signal.

I agree with you - situational awareness is what keeps us safe, and not engaging with poor drivers but rather creating distance.

for braking, I use engine braking at stop lights, and can easily slow down almost all of the way without any brakes applied. Motorcyclists should definitely be taught to drag the rear brake when engine braking to let others know. Most people are unaware of how quickly a bike can slow down, or rather, how so little mass reacts much differently to situations (ex. even going downhill, unless in 5th/6th gear, bikes generally don't pick up speed coasting but rather slow down).

You're making an assumption that someone tailgating you wants to pass. That isn't really true. A decent percentage of drivers just want to tailgate someone.

Well then they can tailgate someone else.

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