shooftie

A late Xmas present made from 3/8″ X 1.5″ steel ( 3/8″ is admittedly overkill). Padlock goes through the hole in the removable bar.

The design is a direct copy of one I saw on the net ( I think made by a German vanagon owner). There are a few variations on the pedal lock theme, I chose this one as it seemed to be the simplest.

It’s a provincial holiday here today, Family Day, and what better use of my free time is there but to dick around with the H4 leds some more. 

One thing I haven’t mentioned before is my puzzlement with what the data sheet says. It states, and it does not specify if this is for the pair or a single, “input power L/25W H/25W”.

Ok then, let’s see if we can make any sense of that. On low beam only the cup shrouded led elements are powered up. That’s half of the available elements on the bulb. And on high beam all the led elements are powered. So how come the wattage figures remain the same?

I hooked a bulb up to a power source and ammeter. The current draw varied with input voltage. At 14V the current  measured 1.20A. At 10V the current measured 1.10A. But curiously, at 11.5V the current measured 1.47A. My power source only goes up to 15.5V, at that setting the current was 1.10A.

That was for high beam, low beam values very similar.

So a couple of things strike me. One is that the current draw had a peak at 11.5V and dropped of on either side of that voltage. Must be something to do with the power regulating circuits in the bulb, I bet it’s obvious to those with a bit of electronic knowledge. The second things is that the current draw was pretty well the same for both high beam and low beam. So that goes a little way in explaining how the spec sheet claims 25w for both high and low beam.
But do my measured values even come close to the spec sheet values? Let’s take the 14V reading, 1.20A. 

(1.20A)(14.0V)= 16.8W

That’s a fair bit from 25 isn’t it? 

Again it’s not clear if the spec sheet is for one bulb or two. If it’s for two then doubling measured value for one bulb would give 33.6W. Closer to 25W but come on…

At this point I get the feeling that either I’m missing something damned obvious or else the spec sheet is inaccurate. 

As I had one of the led bulbs in hand I thought I’d try comparing it to a 55/60W halogen in a couple of 6.5″ e code H4 lamps. These are nice German made Hella lamps, new old stock, unused, meant for the Iltis military vehicle. I thought I’d shine the lamps onto a bit of black card and see what the beam pattern looks like at a very short projection distance.

The lamp(s)

The super sophisticated experimental set up.

Low beam, 55W halogen. Oh I have to add that the batteryused as power source wasn’t at full charge, it’s at 12V. And for some reason the halogen low beam is lass bright than expected. But it’s beam pattern I’m interested in.

Now low beam with the led bulb.

A little different but certainly comparable. More light down low on the led don’t you think?

And now high beam, 60W halogen.

I draw your attention to the defined beam pattern outline, and compare to next, high beam led.

I’d say, and certainly feel free to disagree, that the led beam pattern is slightly less defined. But both quite comparable.

You know it all comes down to the placement of the light emitting elements in the lamp housing. And to how the light disperses from the elements. I think that the led placement is fairly good, but I think (and talking completely without any direct proof) that how the light comes out of the led, how it radiates from the surface mounted elements, differs from how the light emits from a tungsten filament. It’s not an outlandish assertion, the halogen filament is held in space and radiates all around, 360 degrees. The led elements are constrained by being placed on a surface and the best they can do is radiate 360 degrees minus the amount the led back plane interferes ( and that’s assuming that the led elements alone radiate 180 degrees, and I’m not sure that they do).

Ok enough of this for now. I think the thing that will put this exercise to rest will be the side by side comparison with the halogen lights on good friend Simon’s van.

I’ve been trying out the led bulbs since I first posted about them. I still have the same opinion, low beams good, high beams meh. In rain, and in snow, I’m not seeing a much of a drop in the high beam performance though. 

I took a little time tonight to take some pics with a 80/100W bulb in right hand side lamp and the led in the left hand side lamp. I couldn’t find a good wall close to home, I apologize for using that corrugated metal structure.

Ok, here we go, first up is both low beams on. Left is led, right is 80W halogen. Notice the halogen has more of the angled kick, better defined. The led not so much and there is a stray beam at a higher angle.

Now it’s low beam left, led, only. You can see more of the angled beam kick now, not masked by the halogen. That stray angled beam shows up better too.

And now low beam right, 80W halogen. Nice beam definition eh?

On to high beams, first is both high beams on. Not really much to say about this except it’s a blast of light.

This is the 100W halogen alone. 

And the led high beam. Oh boy that corrugated steel is not making things easy is it?

Just as in the original post about the led bulbs I have to say again that pictures don’t capture the compete picture 🙂

Ok now to a gently sloping downhill dirt road. Same drill, same comparison. You be the judge.

So what do I think? I want to like them, I really do. But I’d give them a 7.5/10. I’d like them to be brighter. And I also have the suspicion that the led element placement that I showed in the original post is not quite right (as compared to the filament position in the halogen bulb). I might take the time to play around with a spare lamp and and bulb, on the bench, and see if some adjustment to the bulb projection into the lamp has any effect. 

Update, January 17 2017. I need to clarify a couple of things about this experiment. First, the led bulbs were tried in my Hella 7″ e-code (e 4 to be precise) lamps. The lamps are in good shape, no hazing on the lens and the reflectors are in great shape. They do however have stick on impact protection film applied. The beam pattern, specifically the low beam cut off, appears to be very similar whether it’s led or halogen bulb. But yes I should document that, and if I can find a suitable wall close by I will.

Second, I am having a hard time quantifying or even describing clearly my perception that the high beam distance projection seems less with the led bulb. I think you’ll just have to take my opinion on this for what it’s worth.

Oh and one more thing. The radio interference from these bulbs annoys me greatly. I have a fair bit of pwm regulated led interior lighting and have not noticed any interference from those. I have noticed a little interference from my “built into the bumper ” led back up lights, that should have been a warning I guess. Hindsight is so very very clear isn’t it? The interference effect now cautions me with another pwm project I have on the bench. I will test it in the van before going any further.

Ok, before you say anything, I know. I know the arguments about replacing the halogen bulb in H4 lamps with an led unit. And I agree with them. But, I had to try this.

What got me trying was reading a positive report about a Philips led bulb replacement. What was new to me with the Philips was the location of the led elements on the bulb. It mimicked the location of the high and low filaments of the halogen bulb and also had the little shield on the low beam elements similar to what is on the halogen bulb.

I think the Philips led units, and forgive me for not linking to a source, are around Ca$150 a pair. A bit steep for me but then I found what look to be close copies listed on Banggood. And, unlike other led drop-ins, these are passively cooled via a finned heat sink. Others have fans in the heat sink and for some reason I didn’t like that.

So for around Ca$45 bucks I bought a pair, and they arrived on the slow boat last week.

You can see the led element layout in that pic. Just to be clear they are double sided. And you can see the little shield or shade over the distal elements. Just to be pedantic, here it is compared with a halogen bulb.

I didn’t try to do any measurements comparing the led element positions with the halogen filaments but you can see they are approximately in the same location.

Another view of the led bulb.

It doesn’t look like those little shields on each side line up perfectly does it?

Installating in the lamp is a breeze. The three prong adapter ring is a twist fit on the bulb. You remove that and install the ring on the lamp and clip down the wire bail as you would with normal bulb. This pic shows the led bulb with the adapter ring removed.

And adapter ring installed.

And the bulb goes in with a push and twist lock. It didn’t seem like a very tight twist and lock, not pleased with that. Oh, and the bulb can be inserted in two orientations, 180 degrees apart. You have to be careful to get it right, to have the little shields/shades in the same orientation as the original halogen.

And there you go, lamp goes back into the van. I did this during daylight so a comparison picture ain’t that special. Mind you, taking any kind of picture of lighting is more or less folly. The pictures never seem to tell the same story your eyes do. But I did take a picture with one lamp having the led bulb and the other lamp with a 80/100 halogen. Both are on low beam, cam you feel the difference?

Yup, driver’s side has the led. Seems pretty bright eh? And with all high K value leds it makes incandescent lights appear more amber.

And what about when it was dark? Didn’t take any shots of the lights but I did do some driving. The low beams are nice, like the whiter light on the pavement. But the high beams are not so pleasing. As an aside, I bet most of you know this already, the colour value of the light seems to make a big difference in how you perceive the light. On high beams I was underwhelmed by the projection of the light. It’s hard to put in words, and I honestly can’t explain the effect, but the high beams just don’t seem as strong as the 100W halogens. Well, yes, I am comparing them to 100W so I have to add a grain of salt. What is very noticeable is how bright the reflective roadside signs appear under the led light. 

Once I got onto truly dark roads the lights appeared to project further. Boy this is hard to explain, all so subjective, but cut me some slack I am trying.

Tonight I lined the van up beside my friends Ducato van. Stock lights on that van and it was raining. Once again I’ll say pictures are really not very good at reproducing the actual lighting as I perceived it but here we go.

First pic is my van with led lights, low beam ( my van is on the right hand side of the driveway in all the pics so there will be a light bias towards the right of the driveway due to the low and right nature of the lamp aiming). 

And now low beams from the Ducato. See how amber the halogen appear

And high beams from the Ducato.

And high beams led.

Even though the pics don’t give a true representation of the lights, I think they do show that on high beams the halogens seem to shine further , or at least reflect back from a further distance. But then again it’s not super distinct.

Oh, one thing to note, the sharp cut off on the E code lamps on my van is still maintained with the led bulbs.

But here is the deal breaker. And it shouldn’t have been as much if a surprise as it was. The damn leds create radio interference. It’s only really bad on weak signals, but it’s very annoying. I bet the Philips bulbs do not do this, I bet it’s a result of the cheap price of the units I bought.

So what now? I’ll run them for a while and try to decide if they are worthwhile. I’m not sure of the things I like about them;

low current draw, the quality of the low beam illumination, immediate on/off high/low switching

Is enough to overcome the things I don’t like;

radio interference, long range reach in high beams, no heat on front of lamp to melt ice and snow.