do i need relays?

fdkss03 · 02-11-2009, 11:50 AM

Right now i have my hood bar lights 5 50w bulbs and the kc lights on my jeep.

hood lights and kc lights are run from battery as souce, to switch and then then to the lights. both have fuses in line.

Should I put a relay in line for both circuits or is it ok as is?

dvbum · 02-11-2009, 11:55 AM

Relays are for safety!!

Go to http://www.stu-offroad.com/electrical/elec5/lights-1.htm

to assist you in your project!!

**RaggedOleMan** · 02-11-2009, 12:00 PM

I have a similar situation, switch's & no relays. All are wired to an aftermarket fuse box I added. In addition to auxiliary lights I also installed an interior winch switch from the 12-Volt Guy and that's also wired to the after market fuse box/fuses installed. I've not installed relays for any of them...

I suspect it's a good idea to install relays, but, I'm unclear about "where" in the circuit they're supposed to be installed. Presumably the relay goes between the power source and the switch?

I'd like some advice, too...

dvbum · 02-11-2009, 12:14 PM

Again go to:
http://www.stu-offroad.com/electrical/elec5/lights-1.htm
http://www.stu-offroad.com/electrical/relays/relays-1.htm

http://www.stu-offroad.com/electrical.asp

to assist you in your project!!

**CJ7-Tim** · 02-11-2009, 12:17 PM

You either need relays or fully charged fire extinguisher.

.
http://www.classictruckshop.com/clubs/earlyburbs/projects/bosch/foglites.htm

**Jerry Bransford** · 02-11-2009, 01:44 PM

Relays are DEFINITELY (!!!!) needed for that kind of circuit. While it is a safety issue, the bigger issues are that 1) the lights won't usually run at full brightness the way they're usually wired up when the installer didn't know how to install a relay. And 2) few on-off switches of the size most would choose to install in their Jeep are up to handling the current (amps) drawn by offroad lights so eventually, the switch will very likely fry internally and the lights will stop working. Plus without a relay, you have to run an extra-large gauge wire size all the way to an extra heavy-duty switch which is a PITA.

What I would do is go to an offroad 4x4 store that sells lights and ask for a pre-wired offroad light wiring kit that includes a relay. On the average, I'd run two 100+ watt lights per relay unless you're running small 55 watt bulbs where four lights could be run from one relay. Pre-wired offroad light wiring harnesses are very easy to install, basically just connect one end to the battery + post, ground another wire, and then connect the lights to the remaining wire per the instructions.

dvbum · 02-11-2009, 02:31 PM

X2 on Jerry's recommendations and his motto "Do it right or not at all"

**RaggedOleMan** · 02-11-2009, 07:13 PM

Quote:

Originally Posted by Jerry Bransford

Relays are DEFINITELY (!!!!) needed for that kind of circuit. While it is a safety issue, the bigger issues are that 1) the lights won't usually run at full brightness the way they're usually wired up when the installer didn't know how to install a relay. And 2) few on-off switches of the size most would choose to install in their Jeep are up to handling the current (amps) drawn by offroad lights so eventually, the switch will very likely fry internally and the lights will stop working. Plus without a relay, you have to run an extra-large gauge wire size all the way to an extra heavy-duty switch which is a PITA.

Hmmm...I feel like a fool...I solder each and every connection and thought I did a particularly neat job of the electrical installs!

I read Stu's write up on the relays minutes after I made my earlier post, thanks to the post by dvbum that popped up while I was writing mine... Relay's are definitely on the to-do list now. Thanks dvbum & Jerry...

**RaggedOleMan** · 02-12-2009, 06:59 PM

Quote:

Originally Posted by Jerry Bransford

Relays are DEFINITELY (!!!!) needed for that kind of circuit.

Jerry: Will this procedure work with a three pole (illuminated) rocker switch?

Slithering_Joe · 02-13-2009, 06:44 AM

That'll work but you do not need to connect anything to the 87a terminal.
(statement applies to the diagram above that was removed)

**RaggedOleMan** · 02-13-2009, 10:32 AM

Quote:

Originally Posted by Slithering_Joe

That'll work but you do not need to connect anything to the 87a terminal.

Thanks! Incidentally, the red line indicates the current travel, not necessarily the connection points. What can I say, I'm not a electrical CAD guy...Thanks!

**RaggedOleMan** · 02-24-2009, 06:26 PM

Turns out the original drawing I posted was incorrect. The revised corrected drawing now appears in the original post. Thanks for your help.

**Jerry Bransford** · 02-24-2009, 07:38 PM

Without having my Bosch relay schematic showing what's inside the relay with me here at work or a schematic of the switch internals, it is impossible to know if that schematic will work.

**SirGCal** · 02-24-2009, 07:53 PM

No, that schematic will not work. The power going to the relay for the light should not go through the switch.

Here:

**RaggedOleMan** · 02-25-2009, 11:52 AM

Quote:

Originally Posted by SirGCal

No, that schematic will not work. The power going to the relay for the light should not go through the switch.

Here:

It's my understanding that the switch needs to be powered so it can trigger the electro magnet in the relay. Beyond that...

I've installed the relay per the diagram below and it works great!

That said, I question my wisdom of using the same fused link to power up the switch AND the relay as opposed to two, separate fused feeds: i.e. one for the switch and one for the relay.

SirCal's drawing suggests two separate fused links. I think I like that approach better...nonetheless, the circuit diagram below works in both illustrated scenario's.