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Which diode for duel beam headlights

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gfromleeds

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Discussion starter · #1 ·
Morning guys simple question for the person that knows the answer!
Ive got the aftermarket projector headlights with separate headlight and full beam!
I wasn't overly impressed with the light output so ive upgraded the bulbs to 100w hids and wow what an improvement (its passed 2 mots like this because they are in projector housings so maintains the correct beam pattern )
For safety/overloading reasons ive also rewired them with relays fed from the battery and all works well!
Except when i quickly flash my full beam (ie letting someone pull out) the nissan set up momenteraly turns off the headlights when the full beams are on, and the quick on/off/on/off/on upsets the headlight ballast and they just shut down! Leaving me with no lights at all!
So what im wanting to do is figure out a way of getting the headlights to stay on when i flash my high beam.
Im thinking just connet the output of my full beam relay to the trigger wire of my headlight relay and replace the headlight relay with a slow acting relay to allow for the split second changeover?
But in doing this,it would allow the headlight trigger power from the switch to bleed through to the output side of the fullbeam relay and light up my fullbeams! Unless theres a diode of sorts between them allowing power to only travel from the fullbeams to the headlights and not the otherway around.
Everyone following this? Good cos im struggling to explain it lol
So basically im looking for a link to the right diode i can put inline, bearing in mind its going into an engine bay environment! So would need to be tough and waterproof!

Unless anyone has a better idea?
 
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#3 · (Edited)
I would better use a relay in both headlights, that powers low beam when trigger high beam.
On each diode you will lose at least 0.6V (practically even 0.8V) and you will have to dissipate pretty much heat from 5 amps on each diode.

I'm thinking on doing this too, because the high beam alone is kinda bad joke.
Other option for good light at night drive is to open the headlights and install bixenon lens inside, but will have some taughts at anual car inspection.
 
#4 ·
After market HID's really don't like quick fire on/off. ( A diode won't make any difference)
This looks like your issue to me.
 
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Discussion starter · #5 · (Edited)
diydave said:
After market HID's really don't like quick fire on/off. ( A diode won't make any difference)
This looks like your issue to me.
https://www.youtube.com/watch?v=55z66zl1_Mo
Click to expand...
Yea this is exactly the problem but even doing it slowly it still sometimes does it
I was thinking a diode across the high to the trigger wire of the low beam relay so that when i flash up to high beam the diode would allow the low beams to stay lit up (bearing in mind i have afermarket projectors fitted so seperate bulbs for high and low beam)
Thus killing 2 birds with 1 stone
1 the low beam dont turn off so wouldnt get the ballast fault
2 more light on the road
 
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#6 ·
That diode will just mean the low beams always come on when you are on high beam, so that isn't right.

What would work is that you add in a timer on the low beam circuit that keeps the power on for a second or so when the low beams are switched off. I would suggest a timer relay.
 
Discussion starter · #8 ·
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#10 ·
I used this with my Bi xenon set up.

https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.co.uk/ulk/itm/282730909599

This works my lights fine.

For you you could use the hi beam shield switch to activate your hi beam relay. Probably what I would do to start.

Or you can use the Nissan high beam on the H4 connector to activate the high beam.

Eitherway by using this loom your head lights would always work correctly.
 
#11 · (Edited)
All sounds like a lot of faffing and £££ to me....

I drive at night quite happily on normal H4's. I keep the headlights clean.

Given I'm in a truck, I drive a fair bit slower than in some of the (very) hot cars I have had, as it really doesn't handle too well, so best to keep it modest.... And the V6 is hotter than a few of the cars my wife and I have owned ('cept the good ones)
 
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Discussion starter · #12 ·
freemansteve said:
All sounds like a lot of faffing and £££ to me....

I drive at night quite happily on normal H4's. I keep the headlights clean.

Given I'm in a truck, I drive a fair bit slower than in some of the (very) hot cars I have had, as it really doesn't handle too well, so best to keep it modest.... And the V6 is hotter than a few of the cars my wife and I have owned ('cept the good ones)
Click to expand...
Its not the brightness or speed that's the issue
my main issue its at night when i have my dipped beam on if i flash someone to say im giving way my dip beam seam to have a problem with it!
but i also wanting when im at the farm i would like to put both the low and high beam on at the same time for maximum light output so i know if im gonna drive over a pile of horse sh## or whatever else you find at a horse stable
 
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#13 ·
Maybe the solution is extra lighting units?
They seem popular on this forum, and seem an easy and cheap answer while keeping the headlights standard and entirely legal....
 
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#14 ·
Surely under normal Driving use the vehicle is wired so that the low beam is always illuminated and the high beam comes in on top. That is why I pointed you to the UK law . It seems you have done something that is stopping that .
 
Discussion starter · #15 · (Edited)
Just an update
I bought one of these
https://www.autoelectricsupplies.co.uk/mobile/product/848/category/123
Put it in a fuse holder and bridged the trigger wire of the head lights relay to the trigger wire of the fullbeam relay and it works a treat!
i drive on normal head lights but if i pull up full beam both headlights and fullbeam come on!
And whats more the hid ballast seam happy with it as they now stay on when i flash from headlight to full beam.
Ive since added another to the front fogs so they come on too (just because i can lol)
 
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#16 ·
I think I understand what you're trying to explain here.

You have used the diode to pass power back to the low beam whilst the natural switching of the vehicle momentarily directs current to the high beam during a "flash" pull of the stalk?
 
Discussion starter · #17 ·
mrw27 said:
I think I understand what you're trying to explain here.

You have used the diode to pass power back to the low beam whilst the natural switching of the vehicle momentarily directs current to the high beam during a "flash" pull of the stalk?
Click to expand...
Exactly!
 
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Discussion starter · #19 ·
i just ran the wire under the relays into the top of the sockets so its traped in place when the relay is pluged back in
A bit naughty i know but it worked
 
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