H7 Halogen to LED bulb upgrade

A lot of talk about colour and brightness but none about light spread or 'cut off'.

Low beam needs to be cut off from spreading high to the right so as not to dazzle oncoming drivers.

The pictures in the driveway seem to show a bright centre light with a flood of light going both left and right which seems wrong.

If you take a standard (legal) globe, light pattern, there is a definite line where light is not emitted to the right.

I'd be careful about using LED or any other globe that does not comply with Australian Design Regulations.

Regards

Mike

Technically it is illegal to change a halogen headlight to a LED without changing the reflector because the "upgrade" does blind oncoming traffic.
Sadly most don't worry to much about the oncoming cars because "they prefer the better light" and they never get flashed so it couldn't be to much of a problem[bighmmm]

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Originally Posted by Graeme

The conservation of energy principle states that energy gets converted from one form to another, in this situation electrical energy is converted to heat and light in differing ratios depending on the light-generating source. Watt is the unit of electrical energy (not of light though). The 25W of electrical energy consumed by the LED globe is converted to heat energy and light energy so if the same amount of light is produced as by a 55W halogen globe then the heat will be less than half of that from the halogen. However as the light produced by the LED is greater then the halogen, the heat component will be proportionally less again.

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Thanks for trying to explain Graeme. I'm still a bit confused by the science of the last sentence …. but that's OK. :-)

regarding cutoff lights
led's have the same position source and so the cut off is not changed.
with HID's the source can be different.

I have HIDs in my low beam and the cutoff is the same as Halogens.

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Originally Posted by Celtoid

Thanks for trying to explain Graeme. I'm still a bit confused by the science of the last sentence …. but that's OK. :-)

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Think of it this way :

An incandescent light source is just a heater. As you put more heat into it, the metal starts to glow just like steel does when you weld it or hit it with an oxy. A light bulb is just a heater that is optimised to attempt to put out more light.

If you have a 25W light bulb, it takes that electrical energy and converts it to some light and mostly heat. A LED does the same thing, it's just a 25W LED puts out more light and less heat than a 25W Halogen. As they both consume the same amount of electrical energy, if it's putting out more light, that is less power available to be converted into heat. So it's more efficient (we *want* light, the heat is just a side affect we need to deal with).

As for LED bulb conversions. While the light point source may be in the same position, the light characteristic and spread over the filament length is different and frankly neither the reflector or lens is designed to cater for that. You get inconsistent luminosity across the illuminated field and where the halogens are falling off (as designed to prevent glare to oncoming traffic) the LEDs do not. So the glare to the right side of the road is excessive compared to the designed and approved output, as is the glare and output at the horizontal cutoff (in the mirror of the poor sod in front of you). Yeah in the car it's a case of "Whoohoo look how awesome my new lights are", but to incoming traffic it's not that flash. Thus my question about being able to convert back, because if you get reported or defected you'll want to go back to the halogens to get it inspected.

If you want to be serious about it, grab a copy of "Australian Design Rule 46/00 Headlamps" and read it. Then be prepared to get funky with a flat space, blank wall, measurement instruments and a good light meter, and go to town. For those following along at home, start with Annex 6 "Measuring Screens" and start measuring. If you can comply with those from a geometric perspective (so all your cutoff angles and heights are correct), then move on to the glare and luminosity measurements. It's actually not hard to do the measurements and you don't need expensive gear to do it (although a better light meter helps with the glare measurements). The geometry can be done with post it notes and a good tape measure. The ADR is only ~250 pages, and you can get through it in a night.

As this is my first ever post on this specific topic, I'm going to hit and run and promise to also make it my last. I don't want an argument. If you want to argue, you'd better have the measurements and numbers to back it up and I'll happily take it off line. I've done enough tests locally on cars and bikes to know (and my local IGA now knows I'm the lunatic in the car park at 10pm sticking post-it notes on their wall, using a laser to measure the alignment and moving the tripod and light meter around taking glare measurements).

They are illegal for very good reason. If you want an upgrade your only legal option is to another factory supplied light source, or be prepared to explain to your local engineer your measurement results to demonstrate compliance with the ADRs.

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Originally Posted by Eevo

regarding cutoff lights
led's have the same position source and so the cut off is not changed.
with HID's the source can be different.

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[thumbsupbig]
This has been dealt with in many other threads on the LED headlight topic.
The good quality LED headlight bulbs act in the same manner to a halogen globe due to the shielding that should be provided around the led chips to direct the emission in the correct manner.

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Originally Posted by Celtoid

Thanks for trying to explain Graeme. I'm still a bit confused by the science of the last sentence …. but that's OK. :-)

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This is not how it works, but it's only to help understand Greame's comment.

lets say you have a light and it produces 100 points.
Some of those points will be distributed differently.
so we say that some points come out as heat, other points come out as light, other points come out as 'internal resistance' or losses or whatever.

with a halogen, it may produce 85 points of light, and 14.99 points as heat. 0.01 point is then the losses or whatever else happens.
They have to produce heat, as we experience this in normal usage. Touch a halogen globe a sec after it's been turned off and it burns your hand.

With an LED, it may produce 95 points of light, and only 4.9999 points of heat. and because it runs a much lower current it generates a 0.001 point loss.

So it always has to add up to 100 points; energy in to energy out. How the power comes out(ie. in what form) is the difference.

convert those points degrees Celsius now. if those 15 points = 15°C on the halogen, the LED then = 5°C
same principle applies to the point to lumen conversion.

In reality it's all different to the above, but the idea of it is what kind'a happens.

Funnily at my work.
I work in transport with perishable foods. We have docks that we back up to, and load the trucks, each dock has a large lamp on an arm, they're used to see into the fridge van.
Two docks still have the old 250w flood lights that many homes around the globe use for patio lighting. They produce a lot of heat.
Getting stuck loading the truck for 1+ hr wears you out when you're not used to it all the time. The one aspect I hate are fingers going numb, and jaw getting slow(due to the cold).
I use the old style halogens to warm up my fingers and jaw, as they produce a tone of heat, but compared to the LED docks, you can't see crap into the back(which is actually the front of) of the fridge van.
The LED dock lights produce basically zero heat at all at the globe side. They must produce something, you just feel nothing, just cold. The rear, where most of the heat probably is, is all covered up in an aluminium housing.

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Originally Posted by garrycol

I have HIDs in my low beam and the cutoff is the same as Halogens.

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i should of empathized the word "can".
ive got hids's in 2 of my car and they have a good cut off.never been flashed

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Originally Posted by Eevo

i should of empathized the word "can".
ive got hids's in 2 of my car and they have a good cut off.never been flashed

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When I first put them in on got flamed because every said I will blind every one - hasn't happened, cutoff is the same and the "light" zone of the HID globe is the same as the halogen - yep measured and compared the globes in detail.

I took them back out of Hi beam as the light up time was too long and if you needed hi beam light immediately it was not an option for a few seconds.

A lot of the issues are hearsay and rarely tested by formites who often rely on Mr Google for their "informed" opinion.

Garry

Thanks Graeme, BradC and AK83.

I was tripping over the concept of more light doesn't mean more heat .... because most people would think the reverse …. like when the sun rises, it gets hotter. I understand the concept of energy tranfer being absolute ... you have the same bag of beans at the end, just delivered or used differently. I also understand about losses and how all devices are not equal efficiency wise.

But I was wondering how a LED can produce more light with less heat either at the bright light end or the back end, where energy transfer occurs. That was the point of my original question …. well my original question was about wanting better lights and not damaging my car.

But I don't think I want to hear the answer anymore [bigrolf]