[Sookie]

Just got a light bar and me not being real good with wiring need some help
I am going put light bar on roof mounting to the stock jimny roof rack things, just until I get my bar made up, then will go on there.
My light bar only come with a short + and - wire coming out the back
Can you just earth it and run + wire to batt with a fuse and put a switch inside car inline of the + wire or is that bit risky?
I don't want it to come on with beams or anything like that just a switch so I can turn on when I wheeling ect
And what size wire will I need to run?

■LED Power: 240W
■ Operating Voltage: 10-30 DC
■ Amp Draw(DC): 20A /12V

[Sookie]

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This is what I have been told to do but don't see the point really is it safe to just not worre about relay

[Ausuki]

240 watts needs a relay, its the equivalent of over 4 low beam globes,
you should also switch it through you high beam or cover the light bar when you are on road.

[atari4x4]

you'll want a relay & fuse, just because it's a LED light doesn't mean it's not going to draw alot of power.... especially being a 42" lightbar.

viewtopic.php?f=17&t=4501&hilit=red+wire+silver

viewtopic.php?f=17&t=1108&hilit=red+wire+silver

want33s wrote:

And for those who don't read wiring diagrams so well, try this:

Quote:

On the rear of the driver's side headlight locate the red wire with silver bands around it,

if you have a 12V electrical tester check that this wire is positive when the headlights are on and it then peculiarly goes

to negative when highbeam is on.

Solder onto this wire with a piece of wire long enough to reach back to where you are going to

locate the relay, and attach this wire to terminal number 85.

This will be the "trigger" for the relay, the relay will always have a positive feed to the normal trigger,

and live going to the "switch" of the relay for the auxiliary spots,

so the relay will click closed only when the earth terminal gets a negative feed

(as it will normally be positive...).


Take a wire off the battery's live terminal and with an inline fuse holder connect it to terminals 86 and 87,

these are the normal trigger and the input terminal of the relays switch.

Connect a wire from terminal 30 - the switched output of the relay - and connect this to the positive wire of your spotlights,

the spotlights should also be earthed to either the vehicles body or chassis, or an existing earth point

(probably the best idea I've found).

Hmm, and that's it... when you put your headlights on the wire coming from the soldered joint attached to the red wire

with silver bands will be positive, so the relay will not click closed.

However when you "flash" your headlights or switch to highbeam,

that red wire with the silver bands will drop from positive to negative, then, as the relay now has an earth it

will click closed and switch the positive feed to the spotlights on...

and your spots will come on so you can flash other roadusers, or when you're offroad in the dark, etc...

[Ausuki]

atari4x4 wrote:

you'll want a relay & fuse, just because it's a LED light doesn't mean it's not going to draw alot of power.... especially being a 42" lightbar.

oh yeah and and a fuse

[Sookie]

Ok thanks guys ill have a read throw new info. (To me anywho)
I will not have light bar on car when not really needed everyday drive to and from work hiway driving and more so it don't get knocked off!
So will have to have some kinda plug close to bar so I can remove easy when npt needed

[Mike57]

Sookie

If you are wiring directly to your battery then you can save on the relay as long as you use a switch that is rated for 20 amps continuous use. Do make sure you have the fuse close to the battery, ie connected to the positive terminal. Use a 4 square mm cable minimum but larger if the cable run is not really short. If you are adding a plug and socket make sure they are rated for the cable and for 20 amps as well.

Mike

[Sookie]

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Something like this?
This is the switch I was going to get how ever it ends up wired
Thanks mike

[atari4x4]

if your going to spend that sort of money on a switch, you might as well wire it up properly with a relay & triggered off the high beam so you get the correct illumination on the switch. otherwise your better off just buying a cheapo 20amp plain switch.

[31zook]

If you going to spend time doing something, may aswell do it properly. A fuse, relay and an in cab switch as essential. Plus its illegal to have an independent forward facing light. For the record jimny's are negative switching

[Sookie]

Your right can get a whole wiring kit with a switch for 30 posted so
Might buy the kit and wire that in, then will be done right and I will not have to worry

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[Reubs]

Sookie wrote:

Your right can get a whole wiring kit with a switch for 30 posted so
Might buy the kit and wire that in, then will be done right and I will not have to worry

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That loom looks like junk. There is no way those wires would be suitable for 50A as stated above. That loom would probably be okay for 20A but expect to see some losses!

There is no way you could get a good quality loom posted for $30 either...

[bakerboy]

x2 that loom is a 20amp job, not 50

[Sookie]

Dam! I have paid for it lol
Oh well have find a better one

[droverdave]

How many mm^2 is the wire in that loom?

Only way to figure out its rating.

[Sookie]

Ill ask seller now, just asked him if it really is 50amp and he told me it is (he's going say that anyways)
And he also told me the pic is not of the item ill get he just puts same pic on all he's listing to give a idea of what it is? Sounds dumb to me but anyways

[royce]

also those switches don't work with negative switch headlights real well

go find the wiring spotties thread, the info is all in there and Jimnys are no harder than anything else, but you aren't going to get a drop in fix without spending a lot more than $30

[Mike57]

If I have got this right there is an attachment here to work out what wire size you need for 20 amps or 50 amps or whatever you require.

I agree with all other comments that using a relay and triggering from the high beam is the right way to go. Depending upon what state you are in you might also need to have another switch under the bonnet to disable the light unless you are offroad. Depends upon how particular you are. Only suggested a switch alone as this is what Sookie seemed to be indicating he wanted to do.

Also if you are running 20 amps continuous I would go for a switch with a higher rating or a relay with a higher rating. They never live up to what they say. I always use this relay (New Era), they never fail.

http://www.ebay.com.au/itm/L-K-THIS-SUP ... 2321c46aac

[Sookie]

That is what I want to do mike but just wanna make sure it's safe don't wanna burn my car down
Not really fussed about having a trigger wire with hi beam if there's a way around it still be safe even if I run a relay is there away around having head light as trigger? Then my shit kit And switch i got might be fine if wires are 50amp ect
There will be the + to light bar wire running past driver side inside somewhere as its going on roof for now

[Mike57]

To make it legal you need to have the high beam trigger the light (when the internal switch is on). To make the light work (and work safely) you don't need the relay as long as the switch and wiring can handle the current without melting and you have the fuse right at the battery terminal (which you should have in any case no matter what you do). So you can do exactly what you originally proposed and connect the light bar to the battery via a switch.

As a test why don't you connect it up on the floor with the wire and switch you propose to use and just see if anything gets hot or melts and if you have a volt meter check the voltage drop across the size of wire you are using. If the wire size is too small then (a) it will get hot (dangerous) and/or (b) you will have too much resistance and the voltage drop will be significant and the light will not be as bright as it could be (not so dangerous but inefficient).

You can even test the switch that you have already got and the wiring loom this way, outside the car just hooked up to the battery and then go from there. Just make sure that the test set up has about the same length of wire in it that you would use in the car. If using the car battery leave the engine running and leave the light bar on for a while (like 10 minutes or more). If anything gets at all warm then don't install it in the car. It should not get warm at all if dimensioned properly (or not warm enough for you to notice anyway).

Hope this helps. I might add that this is not best practice but it seems to be what you wanted.

[Critical Energy]

240W/12v =20A, your fuse needs to be as close to that load as possible (25A) wiring etc needs to be able to carry 25A or more, but there is no need to upsize. As for voltage dropped don't worry about it, it's far too short a run to cause issues.

Whatever you do, don't wire it up and feel it with your fingers, there are far too many variables to give you a correct test result.

Rich

[royce]

Jeesus!

You need a relay, I don't care what the packet says, any type of switch with spade terminals on it will either melt with 20 amps going through it or have that much voltage drop you may as well tape a torch to the roof.
Any switch that can carry the current will cost more than any other type of switch and a relay.
Voltage drop is also an issue, any wire you can buy with 25amp on it is too small.

Here, spoon fed instructions.

Get a relay, screw it to the inner guard behind the drivers headlight (or anywhere else, that's just the most straight forward place)
get some 6mm2 cable, some 1mm2 twin cable, a decent fuse holder and 30-40 amp fuse.

Hook the fuse holder up directly to battery positive then connect some 6mm2 cable to it and run it to terminal 30 on your relay.
Hook up more 6mm2 to terminal 87 on the relay and run it up to the positive wire on your light, if you want a plug use one of these
http://www.ebay.com.au/itm/10Pair-x-GEN ... 0775902189
If you get twin core cable for this part you can run the earth back down in a neat single run and earth it under the bonnet
Now get your skinny twin core and cut a short piece to go between the relay and the drivers headlight wiring
look at the rear of the headlight plug, there will be 2 wires that go into vertical terminals on the plug, hook each wire up to one of those wires.
now run some more skinny twin core from the relay to where you want to put your switch and hook it up to the 2 terminals on the switch.
of the 4 skinny wire ends you now have at the relay, take 1 wire from the pair going to the headlight and 1 wire going to the switch and join them together.
now the remaining 2 ends, connect one to terminal 85 on the relay and one to terminal 86.

You now have a light wired up safely that will only come on with the switch on and in high beam, having lights you need to stuff around turning switches on and off are quite shit to deal with, this way is much easier.

[Gwagensteve]

^This.

I would NEVER wire a 20a load purely through a switch.

Steve.

[Critical Energy]

Agreed, though 6mm cable is pointless. 2.5mm is more than adequate, the cable attached to the bar wont be any bigger than that anyway. And keep the fuse to 25A I.e. as close the the load as possible.
Voltage drop won't make an led dim (generally) as they are multivolt, generally 9-32VDC, although dropping voltage will cause the current to increase throwing the other calcs out.
240W/9V =26.6A

[droverdave]

I've just been chatting to the electrical engineer here about this, thought it show my calcs.

AS3008 for cable sizes. I have it in front of me.

4mm^2 in stranded copper is good for 40amps.
2.5mm^2 is good for 30amps.

Now lets look at voltage drop.

Assume that between the battery and the light is 3m, so lets say 2 x 3m = 6m to be a bit conservative.

2.5mm^2 has a resistance per 1000m of 8.4ohms

thus V = I x R = 20 * (8.4/1000 * 6m) = 1.08v voltage drop.

4mm^2 has a resistance 5.06ohms per 1000m

thus V = IR = 20 * (5.06/1000 * 6m) = 0.6v voltage drop.

your car runs at about 13.5 volts when its running.

so with a cable length of 6m, youll get about 12.42 volts at your light bar with 2.5mm^2, and about 12.9 with 4mm^2

Thus i think 2.5mm is sufficent.

And if you can get away with less than 6m of cable, well its a bonus. (not sure where you want to mount it).

[Sookie]

Got my gay cheap loom today

Not bad for 30 dollars if you had a use for it

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But yeah main + wires are only 18awg so no good to me

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[royce]

droverdave wrote:

I've just been chatting to the electrical engineer here about this, thought it show my calcs.

AS3008 for cable sizes. I have it in front of me.

4mm^2 in stranded copper is good for 40amps.
2.5mm^2 is good for 30amps.

Now lets look at voltage drop.

Assume that between the battery and the light is 3m, so lets say 2 x 3m = 6m to be a bit conservative.

2.5mm^2 has a resistance per 1000m of 8.4ohms

thus V = I x R = 20 * (8.4/1000 * 6m) = 1.08v voltage drop.

4mm^2 has a resistance 5.06ohms per 1000m

thus V = IR = 20 * (5.06/1000 * 6m) = 0.6v voltage drop.

your car runs at about 13.5 volts when its running.

so with a cable length of 6m, youll get about 12.42 volts at your light bar with 2.5mm^2, and about 12.9 with 4mm^2

Thus i think 2.5mm is sufficent.

And if you can get away with less than 6m of cable, well its a bonus. (not sure where you want to mount it).

For my money losing 1v isn't acceptable, its a huge drop in light output on a Halogen light that can be overcome for a few dollars in thicker cable.

As said before some LED are multivolt, id like to see some proper tests to see if there is any difference to light output at different voltages

[Blakey]

royce wrote:

droverdave wrote:

I've just been chatting to the electrical engineer here about this, thought it show my calcs.

AS3008 for cable sizes. I have it in front of me.

4mm^2 in stranded copper is good for 40amps.
2.5mm^2 is good for 30amps.

Now lets look at voltage drop.

Assume that between the battery and the light is 3m, so lets say 2 x 3m = 6m to be a bit conservative.

2.5mm^2 has a resistance per 1000m of 8.4ohms

thus V = I x R = 20 * (8.4/1000 * 6m) = 1.08v voltage drop.

4mm^2 has a resistance 5.06ohms per 1000m

thus V = IR = 20 * (5.06/1000 * 6m) = 0.6v voltage drop.

your car runs at about 13.5 volts when its running.

so with a cable length of 6m, youll get about 12.42 volts at your light bar with 2.5mm^2, and about 12.9 with 4mm^2

Thus i think 2.5mm is sufficent.

And if you can get away with less than 6m of cable, well its a bonus. (not sure where you want to mount it).

For my money losing 1v isn't acceptable, its a huge drop in light output on a Halogen light that can be overcome for a few dollars in thicker cable.

As said before some LED are multivolt, id like to see some proper tests to see if there is any difference to light output at different voltages

Majority of all LED's USE a DC-DC SMPS (switch mode power supply) mostly in Boost-Buck configuration Boost being increase Volts and Buck being Lower Volts, so they can take a variety of input voltages usually about 9V-36V and will essentially output Volts and Current that is the same at all input voltages. so that 1V drop will not affect a led driver they only thing that will affect it is load but the load wont change.

so there will be no noticeable difference to a LED

[Reubs]

Sookie wrote:

But yeah main + wires are only 18awg so no good to me

Assuming your 18AWG (0.8mm^2) cable has about 65 mV/A.m loss (extrapolated from data in my Olex catalogue - 1mm^2 is about 52mV/A.m), at 5m of cable that would equate to 6.5V loss, or with 14V at the battery your loom with a 20A load would leave the light bar with just 7.5V... but in reality the current would be higher than that!

If you want an off-the-shelf loom go look at a Piranha DL1 loom or similar...

For the record I pulled an IPF loom out of my SWB Vit and it was rubbish with only a 25A miniature relay and 2mm^2 cable.

[fordem]

droverdave wrote:

I've just been chatting to the electrical engineer here about this, thought it show my calcs.

AS3008 for cable sizes. I have it in front of me.

4mm^2 in stranded copper is good for 40amps.
2.5mm^2 is good for 30amps.

Now lets look at voltage drop.

Assume that between the battery and the light is 3m, so lets say 2 x 3m = 6m to be a bit conservative.

2.5mm^2 has a resistance per 1000m of 8.4ohms

thus V = I x R = 20 * (8.4/1000 * 6m) = 1.08v voltage drop.

4mm^2 has a resistance 5.06ohms per 1000m

thus V = IR = 20 * (5.06/1000 * 6m) = 0.6v voltage drop.

your car runs at about 13.5 volts when its running.

so with a cable length of 6m, youll get about 12.42 volts at your light bar with 2.5mm^2, and about 12.9 with 4mm^2

Thus i think 2.5mm is sufficent.

And if you can get away with less than 6m of cable, well its a bonus. (not sure where you want to mount it).

Your engineer's calculations are fine in a mains wiring system (nominal 230V) where the 1.08v drop represents 0.4%, when you take into consideration that we're discussing an automotive wiring system (nominal 12V), it becomes a 9% voltage drop - now go ask him if a 9% voltage drop across the line would be considered acceptable.

Having said that - as Blakey has pointed out - because of the LED lamps switching converter, it makes no difference to the light output.