Pair of excellent Philips H4 bulbs

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Way2go
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Re: Pair of excellent Philips H4 bulbs

Post by Way2go »

mds141 wrote:Very illuminating thread. :)
Gives you a kind of glow, doesn't it? :wink:
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Re: Pair of excellent Philips H4 bulbs

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MULLEY wrote:Sorry, bit confused, so what would i lose with a simple set up?
Sorry if I went in a bit deeply there! With a simple relay set-up you would lose the dim-dip facility i.e. when you put sidelights on with the ignition the headlights wouldn't come on at half brightness. That may not bother you at all.

If you mean what voltage would be lost with a simple set up, the answer is pretty much the same as with my more complicated arrangement - very little. I get around 0.3 V drop over the wiring from the battery to each bulb, getting on for 0.4 V on main beam which are 100 watts rather than the usual 60. If your voltage drop isn't significantly more than this, there's little benefit to fitting relays.

I found something on the web showing the drop in output with voltage; a small drop makes quite a big difference:

10.5 V - 510 lumens
11.0 V - 597 lumens
11.5 V - 695 lumens
12.0 V - 803 lumens
12.5 V - 923 lumens
12.8 V - 1000 lumens (rated output voltage)
13.0 V - 1054 lumens
13.5 V - 1198 lumens
14.0 V - 1356 lumens
14.5 V - 1528 lumens
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Re: Pair of excellent Philips H4 bulbs

Post by Way2go »

mat_fenwick wrote:
MULLEY wrote:Sorry, bit confused, so what would i lose with a simple set up?
Sorry if I went in a bit deeply there! With a simple relay set-up you would lose the dim-dip facility i.e. when you put sidelights on with the ignition the headlights wouldn't come on at half brightness. That may not bother you at all.
Um :? , now I'm confused. Surely, if you made a simple set-up on a relay with a pair of contacts (DPDT) you could use one side n/o contacts to switch the heavier new feed in parallel to main beam and the other sides n/c contacts to switch the original feed to main beam. This should ensure that it operates without unwanted lock-on when energised from the main beam switch and that the dim dip will still work when on sidelights. :D

Or am I missing something? :?
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mat_fenwick
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Re: Pair of excellent Philips H4 bulbs

Post by mat_fenwick »

Or I might be...let me have a think about it when my brain is fresher. My thoughts on a simple relay system would be one relay to switch on each filament, but if you were using the feed to the dipped beam from the headlight connector as a trigger, the tiny current (to operate the relay coil) passing through the dim-dip resistor would cause very little voltage drop over the resistor, and hence the relay coil would see nearly 12 V and hence turn on. SO you'd have to unplug the resistor unless you wanted dipped beam always with sidelights and ignition.

I'd have to draw out your method to get my head around it but if you reckon it'd work I believe you!
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Re: Pair of excellent Philips H4 bulbs

Post by Way2go »

Ah, my solution above was just bolstering main beam and leaving dip to be fed conventionally. Maybe a second relay can be used in the same way and as the second n/c contact could lift the original feed after the resistor, this might be ok too. Definitely too late now to give it further investigation & thought so will get back to it at another time. :)
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Re: Pair of excellent Philips H4 bulbs

Post by white exec »

My recall of BX headlights (from 25 years back - our '89 19RD) was that they were optically really rather good. We ran ours with 100/80 halogen H4s, with relays on both dip and main, to get the load off the lengthy and meagre wiring, and the lighting switch. Well worth doing.

Since then, a S2 XM has brought with it stupendous main beam (4 x H1 in total) but very indifferent dip beam (2 x H1), thanks to the not-so-wonderful shallow light unit design, and some internal fresnels. Xantia suffered similarly.

For XM, the saving grace has been either Osram Nightbreakers (standard wattage, and white (not the blue versions)), or Philips X-treme - a similar spec and performance.

These lamps have hugely improved (dip) light output on the XM, to the point where it's not a subject for angst any longer. They should also provide BX with a superb light output, and it's now on my list of jobs to do on the 'new' BX acquired this week.

Having used both the Osram and Philips lamps on the XM for some years now, lamp life seems pretty much the same as standard H1s, so no complaint there. Just be aware that there are fake versions of both; Amazon have the genuine hologram-marked articles, but beware of any seriously cheap offers.
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