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heimlich 
VWNOS.com
Joined: November 20, 2016
Posts: 6622
Location: Houston, Texas
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Starbucket
Samba Member
Joined: April 30, 2007
Posts: 4026
Location: WA
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 Posted: Tue Jan 07, 2020 12:21 pm Post subject: Re: h4 Headlight Upgrade-- What relay do I need to get? |
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| Dake wrote: |
| DurocShark wrote: |
And now I feel dumb for dropping H4's on my busses... both my 73 and my 78 had them. No relays or any of that. Worked fine and the light pattern from the Hella lenses was WAY better than from any sealed beam garbage.
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I did the same thing in my 62 Beetle no problems yet.
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I ran 55/100s H4s in my 71 Westy no problems without relay and the extra wattage came in handy when someone failed to dim their brights. |
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H2OSB
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Joined: April 14, 2013
Posts: 1294
Location: Modesto, CA
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| Posted: Tue Jan 07, 2020 1:30 pm Post subject: Re: h4 Headlight Upgrade-- What relay do I need to get? |
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Bus Depot sells a kit with everything needed including relays, wiring, proper H4 lenses for Left hand drive and bulbs(it's been a while so bulbs MAY have been extra or options were available)...they didn't even mind that I don't have a bus.
I have considered upgrading to H4 retrofit L.E.D.s, however, for improved efficiency.
H2OSB
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(o\_i_/o) I'm not a vegetarian because I love animals, I'm a vegetarian because I hate plants. |
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robcy04
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Joined: August 29, 2018
Posts: 207
Location: FL
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| Posted: Tue Jan 07, 2020 2:29 pm Post subject: Re: h4 Headlight Upgrade-- What relay do I need to get? |
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I went with VC3500's and put them into economical flat lens H4 housings (economical is a better word than cheap). I have to tell you that not even on the darkest nights are the high beams needed. They use the stock wiring, and draw less power.
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H2OSB
Samba Member
Joined: April 14, 2013
Posts: 1294
Location: Modesto, CA
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| Posted: Tue Jan 07, 2020 4:31 pm Post subject: Re: h4 Headlight Upgrade-- What relay do I need to get? |
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| robcy04 wrote: |
I went with VC3500's and put them into economical flat lens H4 housings (economical is a better word than cheap). I have to tell you that not even on the darkest nights are the high beams needed. They use the stock wiring, and draw less power.
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Nice. That's what I think I'll do. Mind if I ask what those run per bulb?
H2OSB
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(o\_i_/o) I'm not a vegetarian because I love animals, I'm a vegetarian because I hate plants. |
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robcy04
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Location: FL
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herbie1200
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Joined: April 27, 2006
Posts: 833
Location: Rome - Italy
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| Posted: Fri Jan 17, 2020 1:03 am Post subject: Re: h4 Headlight Upgrade-- What relay do I need to get? |
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| bluebus86 wrote: |
| Boble wrote: |
| Starbucket wrote: |
| Buy a dual headlight relay at your local FLAPS (under $10). You use the existing car headlight wiring to the relay you mount under the hood and run a #8 or 10 wire from the pos. terminal of battery (put a inline fuse near battery incase the wire gets a short) to the relay, that way there is only a few amps through the car switches and relays and the bulbs get full power from battery. I ran 55-100 H-4 bulbs with this setup with no problems but a blinding glare to any driver coming at you with their high beams on when you blast them. |
Starbucket, I was planning to do this.
Question: Can you elaborate a little on where you place the relays, some details on the physical setup? |
I have used four relays, or two.
Using two main wires, say one hibeam, one lobeam from the battery will not leave you stranded with no lights should the main fuse trigger, youll have two circuits, each with own fuse.
I place them relays ahead of the dash, and use the existing wires from lights to fuses for my relay to light wires. I feed the relays power from the battery with a separate wire from battery to each relay(s) for hi beam and lo beam. Fuse them at the battery end, close to the battery. I use heavy wire for these two wires, and run them up to the relays.
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If you use four relays, the idea of using 2 wires from battery is good.
But I suggest to modify the wiring.
Instead to use 1 wire for low beam and 1 for high beam, use 1 wire for left side (lo and hi) and 1 wire for right side, this modification requires only a little rewiring in the relay zone.
Two advantages:
1) if one circuit fails, no risk to remain suddenly without lights on a dark road
2) the current from battery is always fed via two wires, so voltage drop (dissipation) is reduced by 50%. |
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ashman40
Samba Member
Joined: February 16, 2007
Posts: 15989
Location: North Florida, USA
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| Posted: Fri Jan 17, 2020 4:39 pm Post subject: Re: h4 Headlight Upgrade-- What relay do I need to get? |
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| herbie1200 wrote: |
But I suggest to modify the wiring.
Instead to use 1 wire for low beam and 1 for high beam, use 1 wire for left side (lo and hi) and 1 wire for right side, this modification requires only a little rewiring in the relay zone.
Two advantages:
1) if one circuit fails, no risk to remain suddenly without lights on a dark road
2) the current from battery is always fed via two wires, so voltage drop (dissipation) is reduced by 50%. |
Not trying to start an argument but here are my thoughts on this...
| Quote: |
| 1) if one circuit fails, no risk to remain suddenly without lights on a dark road |
This is actually not the primary motivation of the dual-relay circuit. Relays powered directly from the battery provide maximum current flow to higher wattage headlights. The reason for two relays is because the dimmer relay has two separate outputs that will trigger each relay. Ideally, only one relay will be powered at a time so as long as the wire is thick enough to power the HI beam relay it will be enough to power either relay while it is ON.
When running two relays, if one relay fails your only option is to use the remaining one. With a hi & low relay arrangement, when you loose the low relay (most often used so likely to fail 1st) you switch to running high beams (L & R high beams). Sure, it is annoying to the oncoming traffic but you still have TWO working headlights to get home on.
With left & right relays, when one relay or circuit fails you end up with a single working headlight (left OR right). Even if you could get BOTH filaments in the single headlight to work at the same time... it is better to have two working headlights rather than just one.
| Quote: |
| 2) the current from battery is always fed via two wires, so voltage drop (dissipation) is reduced by 50%. |
Consider that the stock headlights are powered off the single shared red #30 wire that comes from the battery/VR. This single wire carries the power for EVERYTHING hanging off the fuse box (the only thing NOT powered by the #30 wire is the rear window defroster). The stock headlights are competing against everything else for their portion of the current coming from this single wire.
By moving the headlights off this single shared circuit to their own set of relays on a dedicated power wire coming from the battery you have already separated the headlights from all the other devices vying for current passing thru that single #30 wire.
While I agree that two completely separate L/R headlight power sources each powered from the battery may minimize the voltage drop to the headlights... by running headlights that are powered directly from the battery you already drastically reduce the voltage drop from the stock arrangement. I'm not certain there is actually a NEED for the redundancy of two relays to each be powered independently from the battery. Unless there is a high risk of loosing both headlights powering them from their own battery power wire already improves their resiliency over stock. As long as you select the proper sized wire gauge to power the relays you could do with a single wire to power both relays and not worry about voltage loss. Especially if using NEW wire.
Heck, you could run EVERYTHING in the car on individual separate wires from the battery for max resiliency but that gets too expensive for no real benefit. You have to decide the right balance of risk vs. resiliency and cost. Consider that the stock headlight system had no resiliency up to the dimmer relay. It is only AFTER the dimmer relay that there are separate wires. The battery powered headlight relays are a big step up, do you really need 3 or 4 further steps up in resiliency? How much is too much for little or no gain.
If you are familiar enough with your wiring that you can add headlight relays... it also means in a pinch, you should also be able to jumper your fuse box to power your headlight fuses from one of the other fuses.
Keep a short length of jumper wire handy and when your headlight switch, dimmer relay or X circuit fail and your headlights go out, you go to the backside of your fuse box and add a jumper between the INPUT side of the #30 fuses (#8 or #9 depending on your model year) to your INPUT side of the low (or hi) beam fuses to directly power them. This will usually get you home on a dark rainy night. 
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AshMan40
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'67 Beetle #1 {project car that never made it to the road  }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!} |
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