As part of a larger project, I needed to run photometric tests with different bulbs. All lamps and bulbs were run on the same goniophotometer, on the same power supply set to 13.5v. I can't share the entirety of the data, but here are some of the highlights from four bulbs tested in two new H4 headlamps.
Bulb "A"
Standard Philips H4 12v 60/55w (p/n 12342), made in Germany
Measured 73w high beam, 64w low beam at 13.5v, which calculates to:
60/53w at 12.0v
67/59w at 12.8v
70/62w at 13.2v
Bulb "B"
Osram Rallye/Hyper H4 12v 70/65w (p/n 64205), made in Germany
Measured 76w high beam, 68w low beam at 13.5v, which calculates to:
63/56w at 12.0v
70/62w at 12.8v
73/66w at 13.2v
Bulb "C"
Philips HB2 + H4 Xtreme Power 9003XP 12v 60/55w, made in Germany
Measured 73w high beam, 69w low beam at 13.5v,
which calculates to:
60/57w at 12.0v
67/63w at 12.8v
70/67w at 13.2v
Bulb "D"
Philips H4 12v Rallye 100/90w (p/n 12569), made in Germany
Measured 90w high beam, 82w low beam at 13.5v,
which calculates to:
75/68w at 12.0v
83/75w at 12.8v
87/79w at 13.2v
For frame of reference, the US standard for the "60/55w" HB2 (9003) is 72/65w max at 12.8v, and the UN/ECE standard for the "60/55w" H4 is 75/68w max at 13.2v. So bulbs A, B and C all meet both standards in terms of power draw. Luminous flux data (lumens) from these bulbs cannot be shared at this time.
Figures given below are peak intensity in candelas, peak intensity location in degrees from H-V, and beam flux content in lumens.
Headlamp #1, designed to conform to an old variant version of SAE photometrics:
Bulb "A"
High beam: 45,260 cd at (0.2° D, 1.2° R), 855 lumens
Low beam: 14,910 cd at (1.6° D, 1.2° R), 524 lumens
Bulb "B":
High beam: 43,860 cd at (0.2° D, 0.8° R), 976 lumens
Low beam: 22,060 cd at (1.6° D, 0.8° R), 650 lumens
Bulb "C":
High beam: 47,110 cd at (0.4° D, 1.4° R), 903 lumens
Low beam: 20,850 cd at (1.4° D, 1.4° R), 615 lumens
Bulb "D":
Not tested with this headlamp
Headlamp #2, designed to conform to UN/ECE Regulation 20:
Bulb "A"
High beam: 55,410 cd at (0.2° D, 0.6° R), 846 lumens
Low beam: 14,430 cd at (1.2° D, 1.8° R), 451 lumens
Bulb "B":
High beam: 55,810 cd at (0.2° D, 0.4° R), 979 lumens
Low beam: 19,490 cd at (1.2° D, 1.5° R), 545 lumens
Bulb "C":
High beam: 59,650 cd at (H, 0.4° R), 923 lumens
Low beam: 20,220 cd at (1.2° D, 1.6° R), 556 lumens
Bulb "D":
High beam: 69,680 cd at (2.8° D, 2.4° L), 1260 lumens
Low beam: 18,720 cd at (1.8° D, 1.6° L), 677 lumens
Before we go too far in drawing conclusions from these results, it must be stressed that only one sample of each bulb type was tested. That was adequate for the purposes of the larger project involved, but to avoid the possibility of an outlier bulb if these results I've posted were the end intention of the project, it would be preferable to run the tests with multiple samples of each bulb type. Nevertheless, the geometry of each bulb was checked and found to be within the specified tolerances, and nothing about the power draw measurements suggests an off-spec bulb.
Probably the most interesting thing to see here is the close similarity between the Osram 70/65w H4 and the Philips Xtreme Power H4 in both power draw and beam performance. The flux in beam differs by no more than 8% between the two, which is very close -- in fact it is well within the variance I would expect to see between two samples of the same bulb type (two of the 70/65w bulbs or two Xtremes, for example). The beam peak intensity difference between these two bulbs is likewise quite small, no more than 7%. Again, this is well within the range one would expect to see from two samples of the same bulb type, which is why it is an interesting result from two different bulbs from two different manufacturers. For all practical purposes, based on these tests the Osram "70/65w" and the Philips Xtreme Power "60/55w" bulb must be considered functionally the same. Further bolstering this conclusion is these two bulb types' very comparable lifetime ratings. (It is reasonable to assume the newer Philips Xtreme Vision would be in this same group of bulbs; I may or may not be able to get some data from at least one of these headlamps with the XV bulb before the project is over, but not at this time.)
We can also see the peak intensity moves around a little from bulb to bulb, but there's nothing here that is surprising or indicative of anything in particular; we expect to see this kind of movement even among samples of the same type of bulb. Also we have to remember that the peak intensity doesn't tell the whole story; it is just one tiny point within the larger high-intensity zone in the beam, and so we can't draw any headlamp performance or seeing distance conclusions by comparing the exact location of the peak intensity with one bulb versus another bulb.
Also interesting is the showing of the Philips 100/90w bulb. This is (by long experience) among the best of the 100/80 or 100/90 rated bulbs. Its actual power draw is less than advertised. This is not a surprise; the power ratings on off-road bulbs have long been mostly about selecting a round number somewhat above the actual power draw of the filaments. Flux in the beam is elevated compared to the other bulbs, but it's within 4% of the Xtreme Power and within 10% of the 70/65w on low beam in headlamp #1. But look at the peak intensity on low beam with the 100/90w bulb -- there's a surprise! It's lower than any other bulb except the standard Philips 60/55w. Bigger difference (benefit for the 100/90w) in flux and intensity on high beam, but now we do have a larger amount of movement in the location of the peak intensity. It's almost 3 degrees down and almost 2.5 degrees left-shifted relative to straight ahead with the 100/90w bulb, compared to the almost-centered location with the other three bulbs.
At the other end of the scale, we see that the 70/65w or the Xtreme bulb really does make a stout improvement over a standard bulb. 17% to 24% more low beam flux, 16% to 29% more high beam flux. 35% to 48% greater peak low beam intensity (in these specific headlamps) with practically identical high beam intensity. Given that the threshold of just-noticeable intensity difference is 15%, those low beam intensity boosts are pretty "juicy" and worth getting.
For quite a while when I have needed an H4 bulb for a frequently-driven vehicle, I have grabbed whatever comes to my hand first, an Osram 70/65w or a Philips Xtreme, never really forming a preference one way or the other. This set of data helps explain why; there's really no overall advantage to one versus the other, and they're both about equally better than a standard bulb.
Bulb "A"
Standard Philips H4 12v 60/55w (p/n 12342), made in Germany
Measured 73w high beam, 64w low beam at 13.5v, which calculates to:
60/53w at 12.0v
67/59w at 12.8v
70/62w at 13.2v
Bulb "B"
Osram Rallye/Hyper H4 12v 70/65w (p/n 64205), made in Germany
Measured 76w high beam, 68w low beam at 13.5v, which calculates to:
63/56w at 12.0v
70/62w at 12.8v
73/66w at 13.2v
Bulb "C"
Philips HB2 + H4 Xtreme Power 9003XP 12v 60/55w, made in Germany
Measured 73w high beam, 69w low beam at 13.5v,
which calculates to:
60/57w at 12.0v
67/63w at 12.8v
70/67w at 13.2v
Bulb "D"
Philips H4 12v Rallye 100/90w (p/n 12569), made in Germany
Measured 90w high beam, 82w low beam at 13.5v,
which calculates to:
75/68w at 12.0v
83/75w at 12.8v
87/79w at 13.2v
For frame of reference, the US standard for the "60/55w" HB2 (9003) is 72/65w max at 12.8v, and the UN/ECE standard for the "60/55w" H4 is 75/68w max at 13.2v. So bulbs A, B and C all meet both standards in terms of power draw. Luminous flux data (lumens) from these bulbs cannot be shared at this time.
Figures given below are peak intensity in candelas, peak intensity location in degrees from H-V, and beam flux content in lumens.
Headlamp #1, designed to conform to an old variant version of SAE photometrics:
Bulb "A"
High beam: 45,260 cd at (0.2° D, 1.2° R), 855 lumens
Low beam: 14,910 cd at (1.6° D, 1.2° R), 524 lumens
Bulb "B":
High beam: 43,860 cd at (0.2° D, 0.8° R), 976 lumens
Low beam: 22,060 cd at (1.6° D, 0.8° R), 650 lumens
Bulb "C":
High beam: 47,110 cd at (0.4° D, 1.4° R), 903 lumens
Low beam: 20,850 cd at (1.4° D, 1.4° R), 615 lumens
Bulb "D":
Not tested with this headlamp
Headlamp #2, designed to conform to UN/ECE Regulation 20:
Bulb "A"
High beam: 55,410 cd at (0.2° D, 0.6° R), 846 lumens
Low beam: 14,430 cd at (1.2° D, 1.8° R), 451 lumens
Bulb "B":
High beam: 55,810 cd at (0.2° D, 0.4° R), 979 lumens
Low beam: 19,490 cd at (1.2° D, 1.5° R), 545 lumens
Bulb "C":
High beam: 59,650 cd at (H, 0.4° R), 923 lumens
Low beam: 20,220 cd at (1.2° D, 1.6° R), 556 lumens
Bulb "D":
High beam: 69,680 cd at (2.8° D, 2.4° L), 1260 lumens
Low beam: 18,720 cd at (1.8° D, 1.6° L), 677 lumens
Before we go too far in drawing conclusions from these results, it must be stressed that only one sample of each bulb type was tested. That was adequate for the purposes of the larger project involved, but to avoid the possibility of an outlier bulb if these results I've posted were the end intention of the project, it would be preferable to run the tests with multiple samples of each bulb type. Nevertheless, the geometry of each bulb was checked and found to be within the specified tolerances, and nothing about the power draw measurements suggests an off-spec bulb.
Probably the most interesting thing to see here is the close similarity between the Osram 70/65w H4 and the Philips Xtreme Power H4 in both power draw and beam performance. The flux in beam differs by no more than 8% between the two, which is very close -- in fact it is well within the variance I would expect to see between two samples of the same bulb type (two of the 70/65w bulbs or two Xtremes, for example). The beam peak intensity difference between these two bulbs is likewise quite small, no more than 7%. Again, this is well within the range one would expect to see from two samples of the same bulb type, which is why it is an interesting result from two different bulbs from two different manufacturers. For all practical purposes, based on these tests the Osram "70/65w" and the Philips Xtreme Power "60/55w" bulb must be considered functionally the same. Further bolstering this conclusion is these two bulb types' very comparable lifetime ratings. (It is reasonable to assume the newer Philips Xtreme Vision would be in this same group of bulbs; I may or may not be able to get some data from at least one of these headlamps with the XV bulb before the project is over, but not at this time.)
We can also see the peak intensity moves around a little from bulb to bulb, but there's nothing here that is surprising or indicative of anything in particular; we expect to see this kind of movement even among samples of the same type of bulb. Also we have to remember that the peak intensity doesn't tell the whole story; it is just one tiny point within the larger high-intensity zone in the beam, and so we can't draw any headlamp performance or seeing distance conclusions by comparing the exact location of the peak intensity with one bulb versus another bulb.
Also interesting is the showing of the Philips 100/90w bulb. This is (by long experience) among the best of the 100/80 or 100/90 rated bulbs. Its actual power draw is less than advertised. This is not a surprise; the power ratings on off-road bulbs have long been mostly about selecting a round number somewhat above the actual power draw of the filaments. Flux in the beam is elevated compared to the other bulbs, but it's within 4% of the Xtreme Power and within 10% of the 70/65w on low beam in headlamp #1. But look at the peak intensity on low beam with the 100/90w bulb -- there's a surprise! It's lower than any other bulb except the standard Philips 60/55w. Bigger difference (benefit for the 100/90w) in flux and intensity on high beam, but now we do have a larger amount of movement in the location of the peak intensity. It's almost 3 degrees down and almost 2.5 degrees left-shifted relative to straight ahead with the 100/90w bulb, compared to the almost-centered location with the other three bulbs.
At the other end of the scale, we see that the 70/65w or the Xtreme bulb really does make a stout improvement over a standard bulb. 17% to 24% more low beam flux, 16% to 29% more high beam flux. 35% to 48% greater peak low beam intensity (in these specific headlamps) with practically identical high beam intensity. Given that the threshold of just-noticeable intensity difference is 15%, those low beam intensity boosts are pretty "juicy" and worth getting.
For quite a while when I have needed an H4 bulb for a frequently-driven vehicle, I have grabbed whatever comes to my hand first, an Osram 70/65w or a Philips Xtreme, never really forming a preference one way or the other. This set of data helps explain why; there's really no overall advantage to one versus the other, and they're both about equally better than a standard bulb.
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