Monday, December 19, 2016

The problem with automatic headlights

Modern car design has an interesting issue when it comes to automatic headlights. Dashboards are increasingly electronic affairs. The days of laser-cut or die-cut plastic instruments with physical bulbs behind them are coming to an end and more and more cars are getting small LCD displays instead. In some cases, the entire instrument panel is replaced with a single giant LCD.
In the "good old days", an aide-memoir to know whether your headlights were on or not was to see if the instruments were lit up in front of you. If you couldn't see the instruments, chances were that your headlights were off. That doesn't hold true any more - the instrument panel is normally always illuminated now - and obviously if it's an LCD display, it's always on. Somewhere on the display there will be an indication that the headlights are on, but now you need to know what the icon is, where it is and what colour it is. Manufacturers haven't been able to come up with a universal icon for this. For example on my Range Rover, the symbol is a green headlight with three slanted lines - that means dipped beam, all lights on. But in my wife's Nissan Leaf, that same symbol means daytime running lights.
This problem is confounded by people's lack of understanding of how automatic headlights work.
With most new vehicles, in an increasing number of countries, even with the headlights turned to the "off" position, the vehicle shows daytime running lights. These are either LED lights or small bulbs in the headlights that are always on. Importantly, in this state, the rear lights are always OFF. This is bad because people become used to thinking their headlights are on all the time, (they're not - DRL's are not headlights), which means when you get into heavy rain, spray, bad visibility and poor weather, the drivers think they're lit up but from the rear, they're completely invisible.
The image below shows the problem. The top one is headlights off, but DRLs on. The bottom one is headlights on. At a quick glance, the dash looks no different. Look more closely and there's a little icon almost hidden by one of the needles that shows the headlight status:
With headlights in the ON position, it's what you'd expect - headlights and tail lights - but now you're relying on people manually turning their headlights on and off in varying weather conditions and at different times of day. This is something we all used to do without any problem but it seems nowadays people simply aren't capable of this simple function, and with the less-than-obvious dash readout for headlight status, it results in people driving around in the dark with a fully illuminated instrument cluster but no headlights turned on.
So automatic headlights seem like the obvious choice, right? I mean a light sensor turns the headlights and tail lights on when it's dark, and off when it's light. No fuss, no muss. Except that due to the design of these systems, they can ONLY see light and dark. This is fine for clear, dry weather, but again, once you get into fog, haze, heavy rain, spray and other bad weather conditions, the automatic function typically doesn't turn the lights on because the ambient brightness of light hitting the sensor is still high, so the system assumes that it's daytime. Which it might be, but you might be driving in near zero visibility spray on a wet motorway. These are conditions where you absolutely DO need all your lights on and now people seem to get into an utter state of confusion because they now have to contend with "OFF" which means "sort of on but not really", "AUTO" which means on when it's dark, but currently off because it's daylight even though it's pissing down with rain, and "ON" which means truly "ON".
And again, because there's no single, standard, agreed-upon icon on the dash that every manufacturer uses to denote that all the lights are actually on, drivers have no reliable, consistent indication of their headlight status.
You'd think this would be easy enough to fix but we're all still waiting .....

5 comments:

Paul Canciu said...

I drive with the lights on at all times (day/night, city/out-of-city). So I really don't have an issue with forgetting to have them on in the required conditions.
But I can see your point, especially regarding the confusion about daytime driving lights. Normally this comes down to people knowing how to operate their own vehicles. Which the majority do. One might get confused with a rental, though.

Silas Humphreys said...

I never touch the headlight switch in my car - they're always on, and go off when the ignition is turned off. For some reason, my ancient Volvo seems to need the help; people seem not to notice it.

Given how many jurisdictions in the US require headlights to be on when the wipers are on, I wonder sometimes why makers haven't yet taken to wiring the car and programming the computer such that whenever the wipers are in a persistent state (intermittent or continuous sweep, but not wash or single-sweep) the headlights are on regardless of whether the driver's had the wit to turn the switch.

Markus said...

Not to mention the problem of entering and leaving a tunnel. Some systems are keen on switching on an doff as soon as possible - be it necessary or not. Even a small tunnel of 150 ft makes cars turn on their lights automatically. Some shadowed areas under a tree - lights go on.

Other manufacturers avoid this unnecessary waste. The cheaper the car the cheaper the sensors ad the more primitive the programming.

David Mackintosh said...

In 1996 I bought a new Subaru Legacy. In this car, you had the standard three-way off-parking-on light configuration. However, when the headlights were on, and the ignition was not in the run position, the car turned the headlights off. This encouraged you to leave the headlights on all the time, since there was no danger of walking away leaving them on and running down the battery.

It baffles me that cars don't have this as a standard. In 1996 it wasn't even a new idea -- my father's 1980-something Saab 900 was similar.

My 2010 Mazda 3 has a "auto headlight" position which will turn the headlights on or off depending on what some sensor says how dark it is, but for me I think the Subaru's solution was superior for exactly the reason you say, in inclement weather your car is less visible.

And I don't know if my driving habits have changed, but it seems I see far more of these idiots driving around with daytime running lights illuminated at night -- like one or two per night, whereas in the past it was more like one or two per quarter.

I don't understand what this reluctance to run full headlights and parking lights all around all the time is. If your budget for operating a vehicle can't stand some $10 bulbs a couple times a decade -- frankly most people probably change leased vehicles more frequently than they change parking light bulbs -- you really can't afford to be driving anyways.

Paul said...

I like the auto-hedlights on my 2012 Charger. The DRLs are a setting, not a switch position as is the "lights on when it's raining" mode. The sensor works very well in that the lights are turned on when it's dim/dark enough to need them, whether for illumination or so others can see me.