Auxiliary light wiring question

I just purchased 2 new auxiliary lights for my vehicle. They're 100w each. The wiring harness I have in the truck for my previous lights is 12g from battery to light, power and ground. I'm stumped because the new lights are wired in 16g. They're a bipin type of bulb.

Will I be ok to add a connector to the 16g light wires and attach it to the 12g harness? I'd like to get full voltage to the lights, of course and maintains safety.

Any insight or advice is appreciated.

Thank you.

dylans said:

I just purchased 2 new auxiliary lights for my vehicle. They're 100w each. The wiring harness I have in the truck for my previous lights is 12g from battery to light, power and ground. I'm stumped because the new lights are wired in 16g. They're a bipin type of bulb.

Will I be ok to add a connector to the 16g light wires and attach it to the 12g harness? I'd like to get full voltage to the lights, of course and maintains safety.

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What auxiliary lamps are they that they're 100W each? What bulb is this?

16ga wire is fine if the run is very short (it can handle 5A to about 15ft, so a 6" or so pigtail is fine), but make sure you use good connectors (not those 'ScotchLok' fold-and-crimp connectors, rather one of the Posi-Products connectors).

Look for the 12-18ga Posi-Tap® No Crimp In Line Tap.

Thank you for the reply.
They're Lightforce 240 Blitz lights, with the bulb that came with it. I believe they're the same as a Philips 7724, but not sure. I've looked around to narrow down a cheaper and maybe better replacement since theirs are about $8 each.

The 16g run will be about 1ft each, since my 12 harness is already a certain length from my previous light installation. I've got to add some 16 to the lights themselves to reach.

I've used weather pack connectors before in a couple of other little projects on my vehicle, and plan to use them again.

dylans said:

The 16g run will be about 1ft each, since my 12 harness is already a certain length from my previous light installation. I've got to add some 16 to the lights themselves to reach.

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If you're going to add extra wire to the lamps themselves, make it 12ga right away. Every additional connector already adds resistance so you want to at least minimize wire resistance. Remember, you're carrying current in both directions so keep the wire gauge as large as you can for as long as you can.

Alaric Darconville said:

If you're going to add extra wire to the lamps themselves, make it 12ga right away. Every additional connector already adds resistance so you want to at least minimize wire resistance. Remember, you're carrying current in both directions so keep the wire gauge as large as you can for as long as you can.

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Got it. I read your recommendation for the posi tap connectors,and I've used them before, however, I'm going to be putting split loom around the exposed wires and connections (other than the weather pack connectors of course). The wires from and near the lights live in a harsh environment being on a full steel bull bar. Shaking and elements and what not. Those taps won't work in split loom, any inline suggestions like butt connectors?

dylans said:

Got it. I read your recommendation for the posi tap connectors,and I've used them before, however, I'm going to be putting split loom around the exposed wires and connections (other than the weather pack connectors of course). The wires from and near the lights live in a harsh environment being on a full steel bull bar. Shaking and elements and what not. Those taps won't work in split loom, any inline suggestions like butt connectors?

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That's the Posi-Lock connector, but a single one isn't designed for such a difference in wire gauge. You can always just wrap it with friction tape or use a larger diameter split loom to accommodate it.

And the bulb is an osram 64623 hlx

Alaric Darconville said:

That's the Posi-Lock connector, but a single one isn't designed for such a difference in wire gauge. You can always just wrap it with friction tape or use a larger diameter split loom to accommodate it.

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I found some step down butt connectors from anchor. They state they accommodate 12-10 to 16-14 wire connections. They're insulated and have adhesive shrink.

dylans said:

I found some step down butt connectors from anchor. They state they accommodate 12-10 to 16-14 wire connections. They're insulated and have adhesive shrink.

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Those Ancor connectors look like they do a crimp instead of the threaded fitting, so be sure to crimp them very carefully so it forms a good mechanical weld. They should work OK if you do it right. (The Posi-Products are great because they are practically foolproof and reusable.)

Alaric Darconville said:

Those Ancor connectors look like they do a crimp instead of the threaded fitting, so be sure to crimp them very carefully so it forms a good mechanical weld. They should work OK if you do it right. (The Posi-Products are great because they are practically foolproof and reusable.)

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Thanks for the input, I'll check out both options.

Alaric Darconville said:

Those Ancor connectors look like they do a crimp instead of the threaded fitting, so be sure to crimp them very carefully so it forms a good mechanical weld. They should work OK if you do it right. (The Posi-Products are great because they are practically foolproof and reusable.)

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I ordered both types of connectors. I went ahead and mocked up the wiring to first find which wire is power and which is ground, coming from the light housing. And to check voltage drop with my current harness and the 8 or so inches of 16g connected together. I read .27V at each light.

I've run into an issue that has made me question the harness I've made. I'm seeing about .6V of drop on the power side and .2V on the ground. The bulbs are bipin and I've never used that type before.

I bought a Hella harness (87199) and replaced the 16g wire with 12g. Battery to relay (15A fused) is 12g now, power from relay to lights is 12g, and 12g from lights to ground. The length of the run from relay to lights is around 5ft at the farthest.

A single 12g wire comes from the relay and splits to 2, to feed each light. I used Anchor step down butt connectors to splice the 2 to 1. I used posi taps at first but the final assembly was too bulky for the space I have unfortunately.

I used weather pack connectors. The lights themselves came wired in 16g but I'm unable to change it.

If you could advise me as to what may be wrong, I'd appreciate it. I'd like to have full power to the lights of course, and have something that is safe and long lasting. The fuse holder gets extremely hot very quickly...

Thanks!

dylans said:

A single 12g wire comes from the relay and splits to 2, to feed each light.

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Take the 12GA wire from the relay output and run it close to the 16ga wires so you can tap into it. Don't make a Y out of it, make an F. (I'll try to come up with a picture of some kind to clarify that.)

Also, at 12.8V, 200W is 15.6A, so you're running the risk of the fuse blowing most of the time.

Alaric Darconville said:

Take the 12GA wire from the relay output and run it close to the 16ga wires so you can tap into it. Don't make a Y out of it, make an F. (I'll try to come up with a picture of some kind to clarify that.)

Also, at 12.8V, 200W is 15.6A, so you're running the risk of the fuse blowing most of the time.

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Thanks for the input again. A picture would be great!

Here is a picture of the lights connector I made. The 16g is very short, I brought the 12g all the way to it.

https://photos.app.goo.gl/Ydte2qba9a7V2owd7

I couldn't seem to upload the photo so I linked it. I hope it works!

I should be using a 20A fuse?

If I understand what you mean by F... I should run a 12g wire straight from the relay output to a light, maybe the furthest one, and also tap into it with a posi tap to power the other light? Same configuration for the ground?

Would a dual output relay be even better? Each light would get its own power wire and each ground could just run straight back to battery. The way it was wired when I got the harness had one ground coming from each light spliced into 3 grounds. So 2 wires to 3. Of those 3, one went straight to battery, one went to the switch in the cabin and one went to the relay.

If I run each light ground back to battery, could I just tap one to tie the switch and relay ground in?

Another option on connections: Sometimes I just solder the connection and slip heat-shrink tubing over it, especially if I have to splice mismatched wires. A typical driving light relay is good for 30 amps, but dual relays will do no harm. You can even fuse each relay, so one lamp shorting out will not take out both. I probably still have some unused dual relays on one of my shelves. **** Cepek sold them, and they could be used as separate relays or in parallel. But they were non-standard, both in size and in needing their own proprietary fuses.

Hamilton Felix said:

Another option on connections: Sometimes I just solder the connection and slip heat-shrink tubing over it, especially if I have to splice mismatched wires. A typical driving light relay is good for 30 amps, but dual relays will do no harm. You can even fuse each relay, so one lamp shorting out will not take out both. I probably still have some unused dual relays on one of my shelves. **** Cepek sold them, and they could be used as separate relays or in parallel. But they were non-standard, both in size and in needing their own proprietary fuses.

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I thought of soldering, the harness came soldered from Hella. I was under the impression that soldering wasn't great for automotive applications, at least in the engine bay, due to constant vibrations and high heat.

I'm interested in a 5 pin dual output relay setup as that seems like it would provide the most direct and un tampered with way to power each lamp. I bought a new fuse kit as well, since I'll need a new one for this project and for future stuff. Standard ATC type.

I purchased a dual output relay, new wire and used a 20A fuse in a new 10g fuse holder for power from battery to relay. I also ran each light ground back to the battery and tapped one for the switch ground and the relay ground, I used one posi lock for the fuse holder to relay and and one posi tap for the 2 small grounds from relay and switch.

Both lights are getting full power now, with a voltage drop of around .2!

The lights are very bright and have a really good reach, I tested them on an off-road drive for 3 hours.

The bulb is an osram 64623 hlx, is there a sutible brighter bulb I could play around with? The osram 64625 hlx?