The Stovebolt Site Forums The Shop Area The Electrical Bay 6 Volt headlight relays

This is one of those questions I feel the need to apologize for asking...That said, I have relays and pigtails in hand to upgrade the headlights. The question is what if any real advantage would I see by running to the battery vs just tying into the 8 ga. wire I've already ran from the 60 amp alternator to the battery?

In theory, I can see the battery acting as a buffer by eliminating voltage surges from the alternator causing the lights to get brighter/dimmer. But I do realize I tend to overthink things.

Thanks, Ron

The best way will be to use a junction block. They are found on many chevys all trough the 70,s 80,s. Are you running a 6 volt alt.?

Yes, 6 volt alternator. Since the 8 ga. runs from the alternator under the radiator to the starter the (current) plan is to tap it near each of the two headlights with a couple of small kearneys.

That is unless there's a compelling reason to run to the battery which was my initial plan.

Ron, There is no reason to run to the battery. AS long as you fuse the line that you're tapping into the battery feed. Tapping into the battery feed twice is not necessary.

Just tap the Feed once and jumper the relay feed to the other relay. Use one relay for normal lights and the other relay for Brights.

My thoughts exactly- - - - -I've been told electrons move at close to the speed of light (186,000 miles per second). A few feet of #8 wire from the battery to the relays won't make a measureable difference with any sort of test equipment I can imagine!
Jerry

If you mean 'kerneys' or 'split-bolts'', I would reread what Wrenchbender had to say. I think split-bolts would be prone to failure in your application.

Absolutely nothing makes a better, lower-resistance splice than the wrapped connection known as a "Western Union" splice. About 2" of insulation is stripped off the main conductor, and the wire that taps off of it is applied around it with 10-15 TIGHT wraps. It gives more copper-to-copper contact area than any sort of butt splice or other connection method. The connection can be insulated with shrink tubing, self-vulcanizing rubber tape, or plain old electrician's tape. Soldering the joint if desired is a bit of overkill, but it strengthens the connection.
Jerry

Thanks all. Wrenchbender and beltfed, thanks to your comments I've been checking junction blocks and I do like what I'm finding. The reason I've considered a kearney (split bolt) is a reluctance to cut the 8ga wire. Every cut and resulting splice/connection is a potential voltage drop point.

A junction block does make it easy, and I can fuse both the high and low beam leads. Theory being if a fuse blows, hit the dimmer switch and still have headlights.

Jerry and Julian, thanks for the confirmation. Looks like I gave to much credence to the battery acting as a buffer.

Now to get busy.

Shoot, guess I should finish a post quicker or check for replies before posting!

I like the "Western Union" splice. I've used it in the past, just didn't know what it was called. I believe there's a formula for calculating voltage drop due mechanical splices in a circuit. I'm an old pipeliner and know little of such things. I do know that my cathodic protection, control and measurement techs would get all worked up over this type detail.

That name came from the method wires were joined back when the telegraph was the state of the art method of long distance communication. Since most telegraph lines were single-conductor solid wire, the tightly twisted splice made a low-resistance connection that was mechanically stronger than the wire itself. Put a hard pull on a properly-wrapped WU splice, and the wire will break before the splice unwraps itself. The same type of joint is very effective when stringing long runs of barbed wire fencing.

https://cdn.instructables.com/F1R/7USF/IRLQLLP6/F1R7USFIRLQLLP6.MEDIUM.jpg

To simply tap a connection off a long run of wire, just strip the insulation off without cutting the wire and wrap the branch circuit tightly around the main conductor.
Jerry

WooooHooooo, just got back from a test drive with the relays in play. Man, the differance is even better than I'd hoped. The wife commented on how bright the lights were as I came through the front gate.

Well worth the app. $30.00 for two 40 amp 6v relays and two fuse holders.

The 6v alternator puts out 7.5 volts and getting full voltage to the lights is the reason for the now bright lights. The replacement wiring harness on the truck when I bought it is sized for 12 volts. The headlight harness wire was 18 ga. What were they thinking?

New wire is 10 ga. from the power source to the relay pigtails, then 12 ga. to the lights.

Thanks Jerry (Hotrod Lincoln) for pushing my button a while back to do this.