Home Forums General Technical Help Halogen Headlights

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  • #15263
    brianw
    Participant
    Club Member

    Hi .. I see the part SKU: LL14 which takes a modern bulb… Is it a direct replacement for the Sealed Beam unit ? With the same curve as the Sealed Beam . Does it have the same “window” to allow the sidelight shine through? It looks like it takes the same connector.?

    #34643
    Ken B
    Moderator
    Club Member

    if you actually click on the item. You will see a second picture which shows the back and you can clearly see the side light is built into the unit. They also have the same curve on the front as the description suggests. The main connector for the halogen bulb is the same, but you may have to put two spade connectors on for the side light connections.

    I have similar H4 conversion on my Corsair, they are very good.

    Sealed beams have not been available new for some time now, but if they still work dont bin them, as the Land Rover boys that go wading mud plugging want them as they dont fill with water.

    #34688
    brianw
    Participant
    Club Member

    Fitted the Halogen lights & they are great, Perhaps the brighter light means other drivers can see me coming & seem to dip their headlights sooner.

    Between the battery live & lights there are a lot of connectors & 2 switches. I found a spade on the back of the light on/off switch running hot & changing that improved the voltage at the light by 0.3V. But how big a volt drop between battery live & light terminal is acceptable ? Has anyone found a benefit fitting relays so the dashboard switches only have to handle a small current ?

    #34689
    JAN
    Participant

    I’ve fitted relays, but voltage drops aren’t the reason. There are six halogen lights on the Prefect and all come on with main beam. That’s a current draw of around 30A, which would be a bit heavy for the standard switches and cables.

    Personally, I doubt the voltage drop on the length of and cross-section of the cables involved would be significant.

    #34691
    Ken B
    Moderator
    Club Member

    Anglia light switches are well known for getting warm. Personally I’d fit a relay if your that worried and also a fuse on the supply side. Having had a short on the lighting side, it all gets a bit exciting when your going along and smoke suddenly appears from behind the dash!!
    Having said that, on my Corsair I have 7″ Lucas halogens and I’ve retained the original switch with no relay (it has a fuse now though), but the switch is a much better design than the Anglia one and doesn’t get all dirty and tarnished up which i think is the primary cause of the Anglia ones getting warm.

    #34694
    brianw
    Participant
    Club Member

    Thanks,,, JAN, that should light the road up like a film set !!. KenB , you are right the lack of fuses is a worry.. So far my switch seems cool. There is a join in the wiring as it crosses the inner wing
    Are these Bullet connectors than can be unplugged , cleaned & put back or just inline crimps that need to be cut?

    #34695
    Confused
    Admin
    Club Member

    The light output from a halogen headlight is rated at around 14.4v

    A 10% drop in voltage equates to about a 25% drop in light output!

    With any car, especially an old one with old wiring, the very best thing you can do to improve the headlights is to run a nice thick (fused) wire directly from the battery, as short as is practical, to a relay, and switch the relay on using the original wiring. This prevents a lot of current being drawn both through the wiring and the switch.

    Don’t forget to put a good earth back in from the bulbs, too.

    Website Administrator

    #34697
    JAN
    Participant

    The resistance of a cable is proportional to its length and inversely proportional to its cross-sectional area. Even at only 12V, the length of the cabling in a car is not a significant factor, especially as the cable diameters in vehicles of this age is far greater than that used today for the same purpose. The resistance through the switch contacts is different issue, though.

    The output voltage of an alternator is 14.2+/-0.2V, so 14.4V is right at the top of the tolerance range. The voltage output is dependent amongst other things on the engine rpm and would normally fall somewhat at idle speeds, at least if the headlights were on. So if there were a 25% decrease at 12.6V, even at a somewhat higher voltage at tick-over but below 14V, a dimming of the lights at that rpm and brightening up when the throttle is pressed could be expected. I haven’t noticed this.

    #34698
    Confused
    Admin
    Club Member

    It seems that I mis-remembered the voltage drop percentages – they are actually much worse than I said a above!

    The following page provides well written explanations and also provides wiring diagrams for installation of relays and better wiring.

    http://www.danielsternlighting.com/tech/relays/relays.html

    You may be one of the lucky ones who has good wiring and connections that haven’t degraded with time, and therefore have not experienced the lighting drops. I’ve done this on two of my own vehicles, and have instantly noticed improvements (with the same lamp units and bulbs, so not an effect of fitting new bulbs)

    Maybe with a more modern car, or one with additional electrical items (radio, heated screen from 105speed etc) pulling more power from the battery and alternator, the effect is more noticed.

    For an hour or so’s work, it’s well worth doing this if you are experiencing issues with light output, to at the very least eliminate this as a cause :)

    Website Administrator

    #34700
    brianw
    Participant
    Club Member

    Thanks.. It sounds like Relays are worth the effort.. The new Halogen lights passed the MOT, (with the engine at tickover) which is half the battle.

    #34707
    JAN
    Participant

    I’d say you have a point, Mr Confused, that the resistances are more likely to occur in the connections than the cables themselves. I split all these and cleaned the bullets and replaced them where necessary and, mostly, replaced the sleeves, giving the bullets a coat of Copperslip before remaking the joints. The point about good earths is equally valid. I used the genuine metal bullets which should be soldered in place rather the crimped type with the plastic coated extensions. Not only is crimping – well, sort of – cheating, but I suspect that the quality of the connection leaves a lot to be desired. They look awful as well.

    #77452
    brianw
    Participant
    Club Member

    4 years On the improvement the H4 bulbs I installed seemed to have faded… ,,,,I measured a 1.5v & 2V volt drop between the battery & the bullet connector on the inner wing & a warm headlight switch, with both dip & beam.

    so I just now installed relays as suggested … Now good & bright again & switch cool… …. The “4.7mm Lucas type connectors” make it a reversible plug in mod.

    Thanks for the advice ….

    The relays also allows me to add a ” head light flash switch” connecting into the Beam wire near the steering column ( switching the Dip Power through both the ” beam relay off ” & ” dip relay on” contacts insures I don’t power both elements in the bulb together)

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