Punto (Mk2/2b) LED Headlight

AnteLo · Jan 27, 2019

Lightning said:
Hi !

I have recently bought these LED "bulbs" from aliexpress :

link (as of 2019-01-26) : https://fr.aliexpress.com/item/Super-H7-Led-lamp-h1-h3-h11-h27-hb3-hb4-H4-Led-auto-Bulbs-Car-Light/32820845291.html?spm=a2g0s.9042311.0.0.40696c37RROAVJ
for my Punto Sporting 2002.
(be aware that the "9000 lumen" mention on the box is for the two bulbs).

Each boxes contains 2 "bulbs" and is sold 15 euros, so I bought 2 boxes for 30 euros to get 4 "bulbs" for both low beam and high beam.
(Notice that on my 2002 Sporting, 1.2 16V, the format of the bulbs is H1, not H7)

There are two LED chip by "bulb".
Electrical power consumption is 32 watts for each "bulb" : that is coherent with the alleged 4500 lumen of luminous flux knowing that the efficiency of LEDs are commonly above 100 lumen/watt.

Installation is "finger is the nose" as long as you drop the front bumper (count an hour).
The cooling fan of each LED "bulb" is not too big to prevent the optical hood from closing, but it's just.

It lights up much better without dazzling other drivers and when in high beam, night vanishes (when in high beam, low beam "bulbs" stay on).

In France, we have no trouble with the law or with the "contrôle technique" (what you call "MOT").

Cheers and drive safe !

PS (note to G8RPI) : I don't understand your "dislike" but nevermind (the ********), I don't care ;-)

Thanks for recommending those blubs, my punto is also 2002 and it has H1 lightbulbs. Do they fit under headlights cover?

jimboy · Jan 27, 2019

Slightly off topic but still on illumination, personally its those cars with rear LED clusters that are overly bright that irritate me, behind a stationary vehicle with the driver sitting on his foot brake just does my head in. Some modern cars have the rear indicator & all the other lights merging into one very bright flash.

Does any one else come across motorists turning off either left or right & only seem to indicate as they are actually at the very point of turning, all merging into the already extremely bright red mass of LED bulbs. In some cases you cannot make out the amber indicator light until the last minute or not all.

That's my morning rant over....:devil: Apologies for the high jack.

Lightning · Jan 27, 2019

AnteLo said:
Thanks for recommending those blubs, my punto is also 2002 and it has H1 lightbulbs. Do they fit under headlights cover?

Yes, it's a matter of millimeters, but you can close the headlight covers.

AnteLo · Jan 27, 2019

Lightning said:
Yes, it's a matter of millimeters, but you can close the headlight covers.

What about light clip? How do you "lock them down"

Lightning · Jan 27, 2019

AnteLo said:
What about light clip? How do you "lock them down"

There is no problem because the bulbs are delivered with a plastic part that is fixed with the clip, then you insert the LED in the plastic part. It's fixed in a safe way because there are small nipples in the plastic part.

g8rpi · Jan 27, 2019

Lightning said:
Yes, it's a matter of millimeters, but you can close the headlight covers.

That will help the airflow from the fan - not.

Lightning · Jan 27, 2019

g8rpi said:
That will help the airflow from the fan - not.

The fact is the airflow is sufficient since I have checked the headlight covers temperature after an hour drive in city driving conditions...

g8rpi · Jan 27, 2019

Lightning said:
The fact is the airflow is sufficient since I have checked the headlight covers temperature after an hour drive in city driving conditions...

Another lack of understanding. It's the temperature of the LED chips that matters, not the headlight covers. Basic physics says for a given power dissipated inside the housing the average surface temperature of the housing will be the same regardless of the fans operation. The LED chips could be well over their maximum rated operating temperature due to poor fan airflow but you can't tell by measuring the lamp housing temperature. The design of the LED appears to suck air in at the rear and blow it out the circumference so flow will be restricted by a close cover near the inlet but this area will stay cool because the hot air outlet is not blowing on it.

Robert G8RPI.

Lightning · Jan 27, 2019

g8rpi said:
Another lack of understanding. It's the temperature of the LED chips that matters, not the headlight covers. Basic physics says for a given power dissipated inside the housing the average surface temperature of the housing will be the same regardless of the fans operation. The LED chips could be well over their maximum rated operating temperature due to poor fan airflow but you can't tell by measuring the lamp housing temperature. The design of the LED appears to suck air in at the rear and blow it out the circumference so flow will be restricted by a close cover near the inlet but this area will stay cool because the hot air outlet is not blowing on it.

Robert G8RPI.

You are wrong.
If the LED was too hot, the cover and the face of the headlight will show exceeding temperature.
This is not the case showing that there is no excessive heat.

g8rpi · Jan 27, 2019

So how many semiconductor cooling systems have you designed?

The power dissipated in the light housing is constant and the LED "chip" is tiny compared to the housing. A typical Cree 15W COB LED has a maximum operating temperature of 150 deg C. and a thermal resistance of 1.7 C/W so the absolute maximum temperature of the mounting base is 125C. For 2 chips and an ambient of 20C the thermal resistance of the "stem" would have to be less than 3.5 C/W This is pretty low and a more realistic 50 deg under bonnet temperatur it would have to be 2.5 just to keep it below absolute max temperature. A 3C/W finned aluminum heatsink might be 100mm x 50mm with 15mm fins.The thermal resistance to the headlight outer case is much higher so it is impossible to infer the LED temperature from the outer case temperature. Ambient temperature will have a much larger effect than the LED chip temperature.
I would have thought a physics teacher would have a better grasp of basic thermal theory.

Robert G8RPI.

Lightning · Jan 27, 2019

g8rpi said:
[...]
The design of the LED appears to suck air in at the rear and blow it out the circumference so flow will be restricted by a close cover near the inlet but this area will stay cool because the hot air outlet is not blowing on it.

I've missed this point...

Showing you are wrong again ;-)

The air flow is sucked from the LED chip and blowed at the rear of the blub :

So, contrary to what you believe, the headlight cover is not at the inlet side but outlet side of cooling air.

So when I test that the headlight cover temperature is 0K, I really test that the LED chip is properly cooled.

What will you invent now ? Just tell me, I will be glad to teach you

g8rpi · Jan 27, 2019

I'm not wrong, I said "The design of the LED appears to suck air in at the rear" the key word is "appears" the diagram is not clear, showing outward "flow" arrows in both positions. o have the LED so can tell what way the airflow actually is, but it is immaterial. If the clearance betwween the back of the LED fan and the headlamp cover is " it's a matter of millimeters," as you say it will reduce the airflow. Even if it is blowing hot air on the rear cover you cannot tell that the LED chips are not overheating by feeling the back of the headlight cover. To take it to the extreme if the was no airflow the LED hips could be well over 150 deg C with virtually no heat transfer to the rear cover.

I do this type of calculation as part of my day job on aircraft including airliners and am fully approved by EASA and the FAA to verify that they are correct and the aircraft is safe.
I'm not going to respond further as you are obviously in denial that you bought something that is illegal, produces incorrect light pattern and is probably overheating.

Robert G8RPI (CEng MRAeS)

Lightning · Jan 27, 2019

g8rpi said:
I'm not wrong, I said "The design of the LED appears to suck air in at the rear" the key word is "appears" the diagram is not clear, showing outward "flow" arrows in both positions. o have the LED so can tell what way the airflow actually is, but it is immaterial. If the clearance betwween the back of the LED fan and the headlamp cover is " it's a matter of millimeters," as you say it will reduce the airflow. Even if it is blowing hot air on the rear cover you cannot tell that the LED chips are not overheating by feeling the back of the headlight cover. To take it to the extreme if the was no airflow the LED hips could be well over 150 deg C with virtually no heat transfer to the rear cover.

I do this type of calculation as part of my day job on aircraft including airliners and am fully approved by EASA and the FAA to verify that they are correct and the aircraft is safe.
I'm not going to respond further as you are obviously in denial that you bought something that is illegal, produces incorrect light pattern and is probably overheating.

Robert G8RPI (CEng MRAeS)

You are wrong...

<end of troll>

Lightning · Jan 27, 2019

g8rpi said:
So how many semiconductor cooling systems have you designed?

"Argument d'autorité ?"
I have never designed a semiconductor cooling system.

So what ?
I don't need to be whatever "semiconductor cooling system" designer to know how heat should be dissipated (remember, I'm a physics teacher)

g8rpi said:
The power dissipated in the light housing is constant and the LED "chip" is tiny compared to the housing. A typical Cree 15W COB LED has a maximum operating temperature of 150 deg C. and a thermal resistance of 1.7 C/W so the absolute maximum temperature of the mounting base is 125C. For 2 chips and an ambient of 20C the thermal resistance of the "stem" would have to be less than 3.5 C/W This is pretty low and a more realistic 50 deg under bonnet temperatur it would have to be 2.5 just to keep it below absolute max temperature. A 3C/W finned aluminum heatsink might be 100mm x 50mm with 15mm fins.The thermal resistance to the headlight outer case is much higher so it is impossible to infer the LED temperature from the outer case temperature. Ambient temperature will have a much larger effect than the LED chip temperature.

I would have thought a physics teacher would have a better grasp of basic thermal theory.

Blah, blah, blah...

The fact is my Punto runs fine with the LED bulb I have installed.
The fact is I have checked that the temperature is OK.
The fact is the LED are still running 0K.
The fact is that crossing drivers are not blazzed.
The fact is that night vanishes on road conditions.

The fact is you can object any theories...

g8rpi · Jan 28, 2019

Lightning said:
"
<SNIP>
The fact is I have checked that the temperature is OK.
<SNIP>
.

So Mr Physics teacher, how do you know what headlight cover housing temperature is OK?

Calculate headlight cover temperature for a LED COB temperature of 150 degrees C at 25 degrees C ambient and 35W dissipation. Show your working out and sources for any material properties or other data used.

Talk is cheap, facts need proof or data to back them up.

Robert G8RPI.

Lightning · Jan 29, 2019

g8rpi said:
[TROLL DETECTED]

What word don't you understand in <end of troll> ?

g8rpi · Jan 29, 2019

Lightning said:
What word don't you understand in <end of troll> ?

You were the one who posted after your <end of troll>

I guess you have nothing to back up your "facts".

Robert G8RPI

dave · Jan 31, 2019

dave · Jan 31, 2019

The news said led lights are not as hot as standard so make sure you clear the frost off them.

g8rpi · Feb 2, 2019

Same applies to HIDs. So they need to be cleared off too. The low power ones without washers are worse, At least a decent screen wash will help with those with washers. Enen a lighr frost can render them useless.

They have had the same problem with aircraft approach lights (PAPI) when changing to LED even condensation on the lens was enough to affect accuracy, They have to fit heaters negating some of the energy savings.

Robert G8RPI.

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