Headlights on all day, and Safespeed
Discussion
motco said:
The simple fact is, though, that nowt's for now't and fuel consumption suffers due to the added electrical load. Multiply a few percent over millions of cars and a whole field full of wind turbines bite the dust, so to speak.
I was under the impression that most alternators are more than capable of producing enough 'leccy to power the sparks, lights and entire electrical system of the car in normal operation, i.e. unless the battery is a bit flat and needs charging, there's power going to waste all the time?
pdV6 said:
I was under the impression that most alternators are more than capable of producing enough 'leccy to power the sparks, lights and entire electrical system of the car in normal operation, i.e. unless the battery is a bit flat and needs charging, there's power going to waste all the time?
please return to school, gcse physics, do not pass go, do not collect £200. once running the car doesnt need the battery, it just an energy store. so where does the power to drive the lights come from? /petrol
see my first post. i estimate this proposal will use 1/2 to 1 million litres of fuel a day across europe.
Given how many halfwits drive with no lights in the winter gloom or use side lights which are just as bad & are practically invisable in the spray of a motorway, (even bikes- whats wrong with these halfwits?) ive long been a fan of a compulsory 'when the clocks go back the lights go on' idea, so when BST comes around switch 'em off.
Not perfect I admit, & the bikes being less noticable point does have merit, but Im for the idea.
Not perfect I admit, & the bikes being less noticable point does have merit, but Im for the idea.
pdV6 said:
The simple fact is, though, that nowt's for now't and fuel consumption suffers due to the added electrical load. Multiply a few percent over millions of cars and a whole field full of wind turbines bite the dust, so to speak.
I was under the impression that most alternators are more than capable of producing enough 'leccy to power the sparks, lights and entire electrical system of the car in normal operation, i.e. unless the battery is a bit flat and needs charging, there's power going to waste all the time?
No, the alternator has a regulator in it so it reduces the alternator output to match the load rather than wasting power. You only get the situation you describe on things like old bikes which have a Zener diode to dump excess power instead of a proper regulator.
pdV6 said:
The simple fact is, though, that nowt's for now't and fuel consumption suffers due to the added electrical load. Multiply a few percent over millions of cars and a whole field full of wind turbines bite the dust, so to speak.
I was under the impression that most alternators are more than capable of producing enough 'leccy to power the sparks, lights and entire electrical system of the car in normal operation, i.e. unless the battery is a bit flat and needs charging, there's power going to waste all the time?
The amount of torque required to turn any generator, alternator or dynamo, is directly proportional to the electrical power being derived from it. Why do you think alternator drive belts screech when cars first start if they're a bit loose? It's because the alternator is busy putting back the energy taken from the battery used to start the car. Once the first heavy current drain is past, they stop slipping normally.
motco said:
Why do you think alternator drive belts screech when cars first start if they're a bit loose? It's because the alternator is busy putting back the energy taken from the battery used to start the car. Once the first heavy current drain is past, they stop slipping normally.
The real reason is that the alternator pulley is much smaller than the crank pulley and it takes some doing to get them up to speed, give it half a chance and it will slip until it catches up.
It takes several minutes to put back the current needed to crank/start a car, not seconds.
The human brain only sees what it is expecting to see. A driver waiting for a break in traffic to join a main road from a side road will not immediately see a driver without headlights on if everyone else has theirs on. It's a similar story with overtaking.
It is exactly the same problem with motorbikes not being seen by car drivers.
The moral of this tedious tale is - make sure you are at least as visible as everone else!
It is exactly the same problem with motorbikes not being seen by car drivers.
The moral of this tedious tale is - make sure you are at least as visible as everone else!
Ribol said:
Why do you think alternator drive belts screech when cars first start if they're a bit loose? It's because the alternator is busy putting back the energy taken from the battery used to start the car. Once the first heavy current drain is past, they stop slipping normally.
The real reason is that the alternator pulley is much smaller than the crank pulley and it takes some doing to get them up to speed, give it half a chance and it will slip until it catches up.
It takes several minutes to put back the current needed to crank/start a car, not seconds.
With respect Ribol, that's not necessarily so. Yes it is significant that the pulley is small but it happens because the initial load is very high and while it doesn't put it back in seconds, it does taper off exponentially in seconds. Try turning the headlights on and you will often start the screeching all over again by tipping the scales just enough to break the grip on the pulley.
motco said:
Try turning the headlights on and you will often start the screeching all over again by tipping the scales just enough to break the grip on the pulley.
The only way turning the headlights will make a belt screech is if it is too loose/slipping in the first place. If you want to add on the hrw and a flat battery then you may stand half a chance with that argument but again if everything is up to scratch that shouldn't do it either.
Ribol, Here's what I said in my first post on this
I was merely trying to illustrate why running with lights on costs you extra in fuel by adding load to the alternator and making it harder to turn. I had no intention to get into an argument about the various causes of fan belt slip! Of course, you're right, a properly adjusted drive belt should not slip at all, or not audibly at least. Now, can we stow the cannons?
motco said:
Why do you think alternator drive belts screech when cars first start if they're a bit loose? It's because the alternator is busy putting back the energy taken from the battery used to start the car. Once the first heavy current drain is past, they stop slipping, normally.
I was merely trying to illustrate why running with lights on costs you extra in fuel by adding load to the alternator and making it harder to turn. I had no intention to get into an argument about the various causes of fan belt slip! Of course, you're right, a properly adjusted drive belt should not slip at all, or not audibly at least. Now, can we stow the cannons?
In some part of the US, whenever you have your windscreen wipers on you are required to have your headlamps on as well. IINM, US versions of some cars have the headlamps come on automatically whenever the wipers are operating.
In that the big concern seems to be that sometimes in the middle of the day one's visibility is obscured because of rain and the darkness that tends to accompany it, why not follow this example from the States?
Wet weather visibility must be the greatest risk. The idea of every car on the road having its headlamps lit during a sunny afternoon in August is ridiculous.
In that the big concern seems to be that sometimes in the middle of the day one's visibility is obscured because of rain and the darkness that tends to accompany it, why not follow this example from the States?
Wet weather visibility must be the greatest risk. The idea of every car on the road having its headlamps lit during a sunny afternoon in August is ridiculous.
I'm a lights on guy. Dublin tried to implement a "lights on" policy a few years ago. A couple of signs went up and that was it (I think they're gone now). I switched on then and have left them on since. I think safety to the driver/cyclist/pedesterian is more important than a bit more petrol. Too many people forget their lights in the rain, permanent lights fix this at least.
up-the-dubs said:
I'm a lights on guy. Dublin tried to implement a "lights on" policy a few years ago. A couple of signs went up and that was it (I think they're gone now). I switched on then and have left them on since. I think safety to the driver/cyclist/pedesterian is more important than a bit more petrol. Too many people forget their lights in the rain, permanent lights fix this at least.
yeah but you driving along with your lights on obscures the cylist/motorcyclist doing the same.
francisb said:
Having your lights on when all about you have none is a bit like standing up in the cinema to get a better view. It works as long as you are the only one doing it. As soon as everyone else does it you're back where you started.
LOL nice analogy
Which is fine by me. When everyone else starts doing it, I will have to think of something else!
james_j said:
This is typical of an idea which seems good in theory, until you think about the reality.
It'll make all other elements which the driver should take into account, like motorcyclists, stupid pedestrians not looking, partially-obscured side turnings and so on less visible.
The human eye, like the eyes of most creatures, will "close up" when presented with bright lights, thus rendering things that are not so bright, darker.
A good pal of mine was killed when a lady drove out of a side road into the path of his motorcycle. He was wearing bright yellow gear and had his headlight on. ( court witness statement)
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