How much wattage can stock headlight wiring support?

[jeremy93ls]

It's been a while since I had to drive my '78 in the dark. The stock sealed beam headlights had me squinting the whole way to work. As soon as I got there, I ordered some 9" glass headlight housings with replaceable H4 55/60 watt bulbs. After installation and alignment, they're only a little better.

I've upgraded a '95 Tacoma similarly and bought 80/100 watt bulbs for it. It was a great improvement. Can the 280 wiring handle 80/100 watt H4 bulbs?

 

 

[SteveJ]

Unless you have relays in the headlight circuit, the issue is that your voltage is too low. I have played around with different types of headlights. I have standard H4 lights at the moment, but the stock wiring is now controlling relays, and I have power for the lights going through the relays instead of the headlight switch. Just a couple of volts increase can make a world of difference in lighting. You'll find that you won't get much more light from the higher wattage bulbs until you address the voltage problem.

By the way, I hope that is a typo and you ordered 7" housings.

[madkaw]

Steve’s right on. You fixed the wrong thing first . Relays would make your headlights 10 times better . I upgraded to Cibie headlight lens , but also relays . Both are a great improvement , but relays are the biggest improvement and save you headlight combo switch and your fuse box too

[jeremy93ls]

Awesome. Thanks guys. I'll look into the relays.

And yes, 7" headlights 😉

[SteveJ]

There might be someone who lives in about an hour away from you who knows about installing relays.

[jeremy93ls]

☝️ This guy 🙂

Steve, you're a gentleman and a scholar.

Have LED bulbs not advanced enough to forgo adding relays and splicing into the wiring? I don't mind modifying the wiring, but can't help to think there's a better way these days. I was looking at this for my wife's ES350 since it didn't come with the HID lights, but haven't pulled the trigger yet. They carry an H4 version, too:
https://www.amazon.com/HIKARI-H7-Headlight-Brightness-Visibility/dp/B07XP1GG13/ref=sr_1_3_sspa?dchild=1&keywords=h7+led&qid=1602976309&s=automotive&sr=1-3-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyVkwyRURPV001UlIyJmVuY3J5cHRlZElkPUEwOTY2MTU4Mk5WUDI5RUZJWUkzUSZlbmNyeXB0ZWRBZElkPUEwOTgyMDg1Q09ETDc5QlBXVERMJndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==

 

[AK260]

My stock wiring with LED bulbs in H4 lenses...



1/3 current of halogens, no relays yet, transformed night time driving, ‘nuff said!

[jeremy93ls]

14 minutes ago, AK260 said:

My stock wiring with LED bulbs in H4 lenses...

Ohhhh... that's nice...

[SteveJ]

53 minutes ago, AK260 said:

My stock wiring with LED bulbs in H4 lenses...



1/3 current of halogens, no relays yet, transformed night time driving, ‘nuff said!

LED bulbs in H4 housings are next on my list to try. I have the bulbs. I have an extra set of H4 housings. I just have to move it up the priority list.

[SteveJ]

1 hour ago, jeremy93ls said:

☝️ This guy 🙂

Steve, you're a gentleman and a scholar.

Have LED bulbs not advanced enough to forgo adding relays and splicing into the wiring? I don't mind modifying the wiring, but can't help to think there's a better way these days. I was looking at this for my wife's ES350 since it didn't come with the HID lights, but haven't pulled the trigger yet. They carry an H4 version, too:
https://www.amazon.com/HIKARI-H7-Headlight-Brightness-Visibility/dp/B07XP1GG13/ref=sr_1_3_sspa?dchild=1&keywords=h7+led&qid=1602976309&s=automotive&sr=1-3-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyVkwyRURPV001UlIyJmVuY3J5cHRlZElkPUEwOTY2MTU4Mk5WUDI5RUZJWUkzUSZlbmNyeXB0ZWRBZElkPUEwOTgyMDg1Q09ETDc5QlBXVERMJndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==

 

The thing is with LEDs is that you MUST have relays. I have not come across an LED headlight that can use 2 negative wires and 1 positive wire. 

I actually did come up with a "no splice" method of integrating the relays for the 72 and 73. I did a proof of concept on a friend's car. It is similar to what Dave Irwin (@Zs-ondabrain) did in the kits sold by MSA. I just get the headlight power from the fuse box. I just need to inspect the wiring in person for a 70 and 71 to design those because some things aren't lining up in the wiring diagrams.

Now it's a different story for the 260Z and 280Z. I have laid out a general design, but the challenge is that with the 260Z, they switched the dash to engine harness plugs to a Yazaki design that I haven't been able to track down. @Captain Obvioushelped me some with developing my ideas in another thread. What doesn't help is that the only source I can find for Yazaki connectors and terminals is Eastern Beaver in Japan. (http://easternbeaver.com/Main/Elec__Products/Connectors/Sealed/YPC/ypc.html) I would need to back out the wires from the connectors at the dash-to-engine harnesses and do my re-wiring there. It is feasible, but I haven't done it, yet.

[AK260]

Fair comment, I’m not sure on the exact wiring differences between an early and later S30 but it worked out of the box on my ‘77.

I am very fussy and don’t like the headlight relay harnesses available and plan to make my own with relays inside the cabin. So LEDs was an easy win in the meanwhile (3 years ago!!). The light you see is with 11.8v at the headlight connector and 12.6v at the battery. They do get slightly brighter when you start the car, so even on LEDs the voltage matters, albeit marginally. The way forward is definitely relays and in in my books x5: one per side per beam, one for the rest of the lighting and in a discrete box under the dash near the heater motor.

That 0.8v drop is still quite a few Watts being dissipated in the car’s old electrics. In fact, I would wager that the wiring is still low impedance but it’s the connectors at the fuse box etc that need a good scrub! Which should be mandatory for us all given how much heat that can generate.

I looked very closely at those Yazu connectors but haven’t bought them yet: has anyone used these and happy with them?

Finally, if you do use the LEDs be sure to install them in the right orientation (it IS different to halogens, ask me how I know)! Halogens are up/down, LEDs are left/right. Most of them have a spinning head.



Good luck chap.

Ps. Mine are Vanssi branded cheapos (about ($60) from China as i was very unsure and it was only ever meant to be an experiment / stop gap, but touch wood in three years and a lot of night driving they haven’t let me down ... yet!

[Captain Obvious]

4 hours ago, AK260 said:

The way forward is definitely relays and in in my books x5: one per side per beam, one for the rest of the lighting and in a discrete box under the dash near the heater motor.

Agreed. I didn't put my relays in the interior (they are out in the engine compartment), but I used four relays. One per side per beam. Not only is it a more fault tolerant system, but it also minimizes the voltage drop in the switching system. Down sides are the obvious cost and complexity, but relays are cheap and the complexity is a once and done thing.

With the relays, I find my old original incandescent bulbs to be quite enjoyable on a dark road.