Really basic wiring questions

[Icewalker]

This is probably a no-brainer for most folks but I profess to being probably the worst person at wiring in 12v systems (You'd never believe I'm a damn good network engineer).

So I'm in the process of wiring in some lights, and ancilliaries into my truck and I'm kind of stuck on the whole wiring process. So here goes:

I have a set of front spot lights, 4 roof mounted spotlights and a pair of rear worklights.

I want to wire it in so that each pair of lights has an independant switch - so does that mean that I need 4 seperate relays?

Also on the relays there are 4 connectors 30, 85, 86, and 87. If I understand the crappy wiring diagram I got with one set of the hellas the wiring goes:

87 - fused 12v in
85 - Ground
86 - to the switch
30 - to the light

Does the switch itself need a seperate 12v in ? i.e. do I need to run power to it in order to trip the relay or is the power already provided by the 12v in?

Told ya these were basic questions - I did a search here and on the web - but couldn't find anything that really explained it to me

Anyone have a good basic diagram ?

Thanks

Jeff

 

[Icewalker]

So this is what I've managed to figure out so far - does it look right?

Thanks

Jeff

 

[slooowr6]

I want to wire it in so that each pair of lights has an independant switch - so does that mean that I need 4 seperate relays?

Yes, 1 per each pair. Make sure it has the corrrect amp rating. Take 2*55W for example, you'll need 110/12 * 1.1 = 10.1 so a 15AMP relay will be enough, and a 15 AMP fuse should be used.

Also on the relays there are 4 connectors 30, 85, 86, and 87. If I understand the crappy wiring diagram I got with one set of the hellas the wiring goes:

87 - fused 12v in
85 - Ground
86 - to the switch
30 - to the light

Does the switch itself need a seperate 12v in ? i.e. do I need to run power to it in order to trip the relay or is the power already provided by the 12v in?

Yes, you don't need a seperate 12 V for the coil.

Told ya these were basic questions - I did a search here and on the web - but couldn't find anything that really explained it to me

Anyone have a good basic diagram ?

On the bottom http://www.2kooltech.com/default.aspx?P=ProductPages/InstallationInstructions.ascx&ProductID=22
connect switch to where they put the remote switch.

 

[Grim Reaper]

So this is what I've managed to figure out so far - does it look right?

Thanks

Jeff

That will work fine. Just be careful of the relay. There are some relays that have a two 87's and some with a 87 and a 87a. The "a" will get you in trouble if you miss it.

I usually like to put power to 30 and if you are using a circuit that would need a relay with 87a that will be the way you need to wire it. The reason being is I sometimes use the the relays with the "a" to do interesting effects. You can actually make a low-beam circuit with a relay with 87a. When the relay is not energized there is a circuit form 30 to 87a the low beam would go to 87a. Once the relay is triggered the circuit is made from 30 to 87 (high beams) and the circuit between 30 and 87a will be broken.

The triggers of 85 and 86 can be wired several ways. You can wire them just like drawn and send 12v from the switch to trigger (86). I like to wire them with a ground trigger so I don't have to worry about finding power and fusing power on the trigger wire from the switch. The way you would do this is make a jumper for your power source to the relay to 86. Now to trigger the relay 85 would need a path to ground through the switch. No power needed for that wire this way. If that wire gets damaged the the lights may turn on but you will not have to worry about any damage off that wire. That is actually how most japanese vehicles are wired with negative triggers.


There is a lot you can do with relays and simple circuits.

Below is my tow rig. The Hella 1,000's Can be turned on and off independently of the lights or I can flip a switch and they will come on automatically with high beams.. The 500 drivings under the bumper can be independent or they will come on with low beams and off with the high beams. I did that to lower power consumption since you can't tell the 500's are even on when the 1000's are on, no need to use the power. The alley lights on the rack are independent always but the rear set can be independent or flip a switch and they come on automatically with the reverse lights. It makes their use passive and automatic.

 

[goodtimes]

I like to wire them with a ground trigger so I don't have to worry about finding power and fusing power on the trigger wire from the switch. The way you would do this is make a jumper for your power source to the relay to 86. Now to trigger the relay 85 would need a path to ground through the switch. No power needed for that wire this way. If that wire gets damaged the the lights may turn on but you will not have to worry about any damage off that wire. That is actually how most japanese vehicles are wired with negative triggers.

The only problem with using the load side to supply the control side is that you have no protection for the control side...If you get a short on the control side it will take 15 amps to shut it down. Personally, I like to fuse the control side too...just look at the amp draw of the coil being used, and fuse it accordingly (just don't confuse the control side and load side).

|fused 12v supply|--->|switch|--->|pin 86|

And while on the subject of fuses...I hate 'em. IMO, self resetting circuit breakers are the way to go (but I'm lazy like that).

The only problem I see with the wiring diagram you made Jeff, is that the on/off switch should not be grounded, where you have the ground, you want a fused 12v power source. Unless you want to wire it as Grim has suggested. In which case you want to run a jumper from 87 to 86, and move your on/off switch to pin 85.

|85|--->|switch|--->|ground|

There is link in here somewhere to a diagram I posted for JeffryScott awhile back...but I am running late for work and gotta get out of here....

 

[Grim Reaper]

The diagram on the bottom is exactly what I mean by running the jumper to one side of the relay trigger. just add a fuse at the battery.

You can actually buy relays already set up this way that would only have three terminals. 30 for source power and positive side of the trigger, 87 for the device you wish to turn on and 85 to be triggered when it goes to ground. Very common in German cars and Japanese cars. even the horn circuit in may cars use that style relay.

The control circuit would be protected by the fuse at the battery. The coil is rated at 200-300 milliamps to trigger so the current even possible on the trigger wire to the switch would never be able to pull enough current to be an issue if the relay did some how short out.

Image from here:
http://www.classictruckshop.com/clubs/earlyburbs/projects/bosch/relay.htm

 

[Grim Reaper]

Here is a nice PDF on ways to use a relay including how to wire them to make power locks.
http://www.tune-town.com/relays.pdf

 

[Whoknows]

Helpful thread. I'm doing some simple wiring myself -- some LEDs. And, I'm just as lost. I purchased a driving light switch to control the lights that has a small LED illumination light contained in the switch. I have not used a relay though the wiring diagram that came with the switch suggests I need to. I got it to work w/o a relay, but when in the OFF position, there is still 2.8 volts flowing -- my guess is to power the light in the switch which stays on all the time. Problem is that this lights up the LEDs slightly too. Will a relay solve this?

 

[slooowr6]

Helpful thread. I'm doing some simple wiring myself -- some LEDs. And, I'm just as lost. I purchased a driving light switch to control the lights that has a small LED illumination light contained in the switch. I have not used a relay though the wiring diagram that came with the switch suggests I need to. I got it to work w/o a relay, but when in the OFF position, there is still 2.8 volts flowing -- my guess is to power the light in the switch which stays on all the time. Problem is that this lights up the LEDs slightly too. Will a relay solve this?

Is there a different connecter for the LED on the switch or there are only 2 connecters? If there are only 2 connecters then I don't think a relay will help. The LED is always on means there is a small current flow throw the switch at all time. The coil side of the relay rely on the swich to be on/off cause the coil itself is always connected. When switch is on current flow through the coil and energize it and that will activate the load side of the relay. If there is a different connecter on the switch for the LED then you need to use a switched power for it, ex. a power source controled by your ignition switch like the power to you radio. Depends on how you use the light control by this switch you can decide where to get this switched power. Possible source can be radio power (LED on when ignition switch is on), low beam (LED on when you turn on low beam), the light control by this switch (LED on when the light is on).

 

[goodtimes]

The control circuit would be protected by the fuse at the battery. The coil is rated at 200-300 milliamps to trigger so the current even possible on the trigger wire to the switch would never be able to pull enough current to be an issue if the relay did some how short out.

Now that I think about it more, you are correct. The short I am (was) thinking of would simply not happen...it would have to be between pin 86 and the coil.

 

[Whoknows]

Thanks, I appreciate it. What I'm gleaning is I have the wrong switches for this mod. It is on my trailer and I don't have a "switched" power and don't really want any draw on the battery when is sits for long periods. Love this forum.

Thanks,

David

 

[Grim Reaper]

Now that I think about it more, you are correct. The short I am (was) thinking of would simply not happen...it would have to be between pin 86 and the coil.

 

[Icewalker]

That's why I love this forum - there's always so many knowledgeable folks about. Thought I'd show you my meager attempt at wiring up the fuse block today.

Does it look ok?

Jeff

 

[Grim Reaper]

looks first rate!

Bonus points for the shrink wrap.

 

[Icewalker]

looks first rate!

Bonus points for the shrink wrap.

Thanks Grim - This is my latest wiring diagram for the setup - I think it's right but can anyone see any glaring problems?

Also got a relay layout from an existing install - are there any pro's or cons with going this way?

The other question I have is .... What size battery cable? I'm seeing either 6, 4 or 2 guage ?????

Thanks

Jeff