Anybody know what the amperage draw on the headlights is?

[ThisGuyUKnow]

I have copper blocks at different locations that are all 10ga wired back to the neg. terminal of the battery. In a perfect world a ground is a ground, in a CJ a ground can be an illusive thing.

Just personal preference I guess I am lucky cause i havent had ground issues in my 2 cjs i have owned, but if I did I would probably invest my time in figuring out why ive lost ground to that body panel.

 

[IOPort51]

Just personal preference I guess I am lucky cause i havent had ground issues in my 2 cjs i have owned, but if I did I would probably invest my time in figuring out why ive lost ground to that body panel.

I like to fix problems rather than treat symptoms.

 

[Peanut Butter]

I'm going to chime back in here and defend my opinion. First we were not talking about building wiring harnesses for other. I believe the point was to upgrade the headlight wiring and add a couple of relays in. Why add relays if you are going to use 16g or 14g wire. It is just not needed. My suggestion of 10g wire would prevent there from ever being a problem. Lets consider a couple of other things with this project. First wire degrades when exposed to heat. Engine compartment equals lots of heat. The larger the wire the less the amount of degrade from heat (also considering the type of wire is important here). Second, any draw of current through a wire is increased with resistance which is heat. The larger the wire the less resistance to a certain extent. So the use of 10g or even 12g over 14g and 16g is well worth the expense in my opinion for a one time job. As ordinary halogen lights degrade the have a tendency to draw more power. Not a lot but some. This is again countered by a larger wire. In the near future I will be rebuilding my wire harness as opposed to buying one. I plan on using larger wire than necessary, because I don't plan on ever doing it again. I will use relays alot, wrap all of it in wire loom, and that wire that lays next to the engine will be wrapped in a heat protector. Over kill? Sure! But I've seen engine compartments and the whole vehicle burn up from a shorted wire. Doesn't happen very often, but boy those small wires will burn like a canon fuse when shorted. Again just my reasoning IMHO. Rod

 

[ThisGuyUKnow]

I'm going to chime back in here and defend my opinion. First we were not talking about building wiring harnesses for other. I believe the point was to upgrade the headlight wiring and add a couple of relays in. Why add relays if you are going to use 16g or 14g wire. It is just not needed. My suggestion of 10g wire would prevent there from ever being a problem. Lets consider a couple of other things with this project. First wire degrades when exposed to heat. Engine compartment equals lots of heat. The larger the wire the less the amount of degrade from heat (also considering the type of wire is important here). Second, any draw of current through a wire is increased with resistance which is heat. The larger the wire the less resistance to a certain extent. So the use of 10g or even 12g over 14g and 16g is well worth the expense in my opinion for a one time job. As ordinary halogen lights degrade the have a tendency to draw more power. Not a lot but some. This is again countered by a larger wire. In the near future I will be rebuilding my wire harness as opposed to buying one. I plan on using larger wire than necessary, because I don't plan on ever doing it again. I will use relays alot, wrap all of it in wire loom, and that wire that lays next to the engine will be wrapped in a heat protector. Over kill? Sure! But I've seen engine compartments and the whole vehicle burn up from a shorted wire. Doesn't happen very often, but boy those small wires will burn like a canon fuse when shorted. Again just my reasoning IMHO. Rod

Because all the power for the headlamps runs through the headlamp switch which over time gets rust, dirt, dust, and other debris in between the contacts, which causes resistance (heat) in the switch and can cause it to burn up. That also causes the loss of voltage that Jimbo was talking about. Relaying the lights regardless of the gauge lowers the resistance in the ckt and allows the lights to get a full 12v and draw its max amps allowing them to burn brighter.

If you use wire that is too light duty it could burn up like you said. I think you should always make a ckt able to withstand slightly more than what you will be pushing through it. However you dont need to bring a howitzer to a fist fight. I started the thread because I wanted to know how many amps the ckt drew so I could figure out what the min wire needed to handle the load at the distance and then go one size larger. Which 16 ga is the minimum needed to handle the current so I'm going to build the CKT with 14 guage becuase 14guage can handle much more than the 10-11 amps. 12ga would be able to handle a heck of alot more than the demand.

10ga would be nuking the ckt, yes it would handle the without a question handle the ckt forever and ever but using your logic 12ga would meet your criteria. if you are worried about engine fires, I would go through your factory harness and replace all the crimped connections with soldered connections.

 

[IOPort51]

one question, two points

Do you think you could do something like this with 10 or even 12ga wire?
not and remain sane.

The 40 amp relays have 14ga wire on the contacts. this is the week link in the circuit wiring and it is more than capable of carrying the load.

If the wire lights up, you put the fuse in the wrong place.

 

[Jimbos76cj]

I think you misunderstood what I was saying , I didnt mean one rly i ment you shouldnt need 2 fusese. You only need one fuse in the CKT before pin 30 on both relays if they are wire like the attached link. You want to keep ckts as simple as possible.

Using 12ga wire is fine but my point was it was unnecessary to handle the current. By all means keep using it in your manufactured kits they are clean and look great.

I generally like to build ckts one step higher than what they need. Everything I am seeing is showing that at those lengths the bare minimum I can get away with is 16 ga for those amps. So when i build mine I will go with 14 gaugean probably 1 15a fuse between the bat and pin 30 on both relays.

I think as wire gauge goes it's half engineering and half preference. For the why 2 fuses

1) easier for me to get 1-12ga wire crimped and into the relay socket
2) redundancy. God forbid your driving down the road and your headlight fuse Blows. One fuse = no more lights 2 fuses equals quick step on the high beam switch for lights.

The extra $1.50 for a fuse holder makes me feel warm and snuggly on the inside.

For my personal jeeps I use self resetting relays as opposed to fuses.

 

[ThisGuyUKnow]

one question, two points

Do you think you could do something like this with 10 or even 12ga wire?
not and remain sane.

The 40 amp relays have 14ga wire on the contacts. this is the week link in the circuit wiring and it is more than capable of carrying the load.

If the wire lights up, you put the fuse in the wrong place.

I guess that is really the rub here for me. I am Limited by the wiring attached to the relays in the PDC. I have two relays with a 14 ga wire on the output side. I needed to figure out if that would be sufficient to power the lights.

 

[ThisGuyUKnow]

For my personal jeeps I use self resetting relays as opposed to fuses.

So if the ckt pulls too much juice it doesnt bust or burn out, once you fix the problem you can reuse the relay?

 

[ThisGuyUKnow]

I think as wire gauge goes it's half engineering and half preference. For the why 2 fuses

1) easier for me to get 1-12ga wire crimped and into the relay socket
2) redundancy. God forbid your driving down the road and your headlight fuse Blows. One fuse = no more lights 2 fuses equals quick step on the high beam switch for lights.

The extra $1.50 for a fuse holder makes me feel warm and snuggly on the inside.

For my personal jeeps I use self resetting relays as opposed to fuses.

Redundancy makes sense.

I will always use the least amount of fuses and relays in a ckt as possible. Most factory harnesses only have one fuse for the headlamps hi/lo

 

[cj7inthetwigs]

So if the ckt pulls too much juice it doesnt bust or burn out, once you fix the problem you can reuse the relay?

The relays would be similar to the circuit breakers found in your electrical panel inside your dwelling. Once problem is corrected , circuit can then be energized and everything operates normally .

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[ThisGuyUKnow]

The relays would be similar to the circuit breakers found in your electrical panel inside your dwelling. Once problem is corrected , circuit can then be energized and everything operates normally .

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interesting, besides the fact you dont (not very expensive) have to buy fuses for spares what is the benefit in an auto application ?

 

[Jimbos76cj]

Auto resetting will open when it over heats then close once it cools off. If you were to rub some where or have a short it opens to keep from frying. Once it cools off it will close. Depending on how hot it got and how long it stayed hot for it could be open for a few minutes to a few seconds. Once you figure out what the issue it it will work like normal. No need to change out any parts. I install mine after the relays to easily seperated into right and left light. Again I use seperate for high and low just as a built in safety.

To do it "correctly" it should be before the relay but since my relay power feed is only 6" long I roll the dice.

I know two people hurt by jeep headlights malfunctioning. One is a quad and one is dead. I make sure my lights stay on.

 

[IOPort51]

I guess that is really the rub here for me. I am Limited by the wiring attach ed to the relays in the PDC. I have two relays with a 14 ga wire on the output side. I needed to figure out if that would be sufficient to power the lights.

You are trying to do this? are you not? I tried it and could not make it work. Maybe it would be OK if I had found the crimp terminals that went to the relays and the fuses so I could have some sort of wire managment. If you do manage to find the proper crimps I would like to know where, it will come in handy some where down the line, to be sure.

 

[Jimbos76cj]

I've never looked at the crimps on the inside of a fuse box like that. I get my terminals from delcity.com. The ones I get from there will replace the terminals in the relay sockets and most of the stock blade style connectors. I'm about to take a Cherokee to the scrap yard. I'll remove the block from that to see what it looks like.

 

[PaRenegade]

Ive never had problems with getting a decent ground at the grill or fender, If that is the case then yes it makes sense to send the ground to the bat or the engine, but if that is the case then you need to seriously look into why you have no ground on your fenders or grills because you have some serious issues, like maybe your fender isnt bolted to your frame or something

If I may just interject my opinion on grounds. Yes you can get a ground about anywhere. But all grounds are not equal. Just as the best source of power is a copper wire, the best source for ground is also a copper wire. If you run power to the device with a direct line of copper, but then expect the ground to get back via sheetmetal, plate steel, rusty bolts, cast iron, or partial contacts thru paint; your choking out the flow. Think of it a constant flow of water (electrons) in a 1" pipe from a pond (battery) to a pump (device/lights) and back to the pond (battery). If you change the return line to 1/2" pipe at will restrict the flow and slow the pump down.

Not sure if that's a very good analogy but my point is the most efficiency will come from having an equal input and output. So a dedicated ground will always get you the brightest lights. And Jeeps are of poor design when it comes to ground paths. And if I recall correctly, some of you electricity guys correct me if this is wrong, but I believe I read that dc current flows from the negative terminal to the positive side, which is reverse of how we typically think of it. So the ground side is the supply side.

If you have multiple ground needs you can always create a buss bar or ground post in a central location, feed by one large gauge cable, that can supply several smaller ga. wires, thereby limiting your wire runs.

 

[ThisGuyUKnow]

If I may just interject my opinion on grounds. Yes you can get a ground about anywhere. But all grounds are not equal. Just as the best source of power is a copper wire, the best source for ground is also a copper wire. If you run power to the device with a direct line of copper, but then expect the ground to get back via sheetmetal, plate steel, rusty bolts, cast iron, or partial contacts thru paint; your choking out the flow. Think of it a constant flow of water (electrons) in a 1" pipe from a pond (battery) to a pump (device/lights) and back to the pond (battery). If you change the return line to 1/2" pipe at will restrict the flow and slow the pump down.

Not sure if that's a very good analogy but my point is the most efficiency will come from having an equal input and output. So a dedicated ground will always get you the brightest lights. And Jeeps are of poor design when it comes to ground paths. And if I recall correctly, some of you electricity guys correct me if this is wrong, but I believe I read that dc current flows from the negative terminal to the positive side, which is reverse of how we typically think of it. So the ground side is the supply side.

If you have multiple ground needs you can always create a buss bar or ground post in a central location, feed by one large gauge cable, that can supply several smaller ga. wires, thereby limiting your wire runs.

Thats a good point. The direct wire to the neg side of the battery provides less resistance in the system. You can test resistance with a multimeter. I have had the luck to have to rust free cjs which is probably why I haven't had grounding issues, if you have rust between the panels and frame and stuff you might have alot of resistance between the the panel and the battery.

 

[IOPort51]

I've never looked at the crimps on the inside of a fuse box like that. I get my terminals from delcity.com. The ones I get from there will replace the terminals in the relay sockets and most of the stock blade style connectors. I'm about to take a Cherokee to the scrap yard. I'll remove the block from that to see what it looks like.

SPECIALTY ELECTRICAL - The Repair Connector Store

You may find this interesting or frustrating.

 

[ThisGuyUKnow]

You are trying to do this? are you not? I tried it and could not make it work. Maybe it would be OK if I had found the crimp terminals that went to the relays and the fuses so I could have some sort of wire managment. If you do manage to find the proper crimps I would like to know where, it will come in handy some where down the line, to be sure.

Yes I am going to use one of those from a cherokee. It could in theory be any vehicle on the market. Im not sure what you mean by the crimps? are you talking about the connections for the relays? some cherokees and YJ have more relays than others due to different accessories.

I am going to take that pdc and rewire it up so that I have my 2 fan relays, fuel pump relay, and head lamp relays if there is room. I am then going to use the starter relay in the PDC to fire my starter (I have a mini torque with built in solenoid) and use the pdc's main power connection to the alternator and completely eliminate the fender solenoid. all my fuses for the fuel injectors, fuel pump, ecm etc will be in the pdc.

 

[ThisGuyUKnow]

I've never looked at the crimps on the inside of a fuse box like that. I get my terminals from delcity.com. The ones I get from there will replace the terminals in the relay sockets and most of the stock blade style connectors. I'm about to take a Cherokee to the scrap yard. I'll remove the block from that to see what it looks like.

Is the engine harness on your scrap Cherokee intact? If so Ill take the harness off your hands, I have been trying to collect up harnesses to thin out for 4.0 Injection conversions.

 

[cj7inthetwigs]

PaRenegade, you are correct. Electrons are negatively charged so flow from negative to positive. The water analogy is the most common way used to explain flow. The worse thing is that while I am a electrician , I am usually running racks of rigid conduit or cable tray 100' in the air…. If you dont practice, you tend to not retain things . I also deal with alternating current 99% of the time. All in theory .

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