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led light bar on my suv


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redneckincanada 
Member - Posts: 4
Member spacespace
Joined: October 18, 2014
Location: Manitoba, Canada
Posted: October 18, 2014 at 6:19 AM / IP Logged  
Hey,
I have an '02 Nissan Pathfinder and recently purchased Four 6-inch 40W LED flood light bars. I'm using them as extra lighting for off-road use in remote areas for better visibility.
They didn't come with much except a pos & neg wire coming off them and mounting brackets.
I want to hook all of them up to one toggle switch, however I don't know what type of switch to purchase. Do I buy a switch with 3 connections (pos,neg & acc), then hook up all 4 positive wires coming off the light bars to the "acc" part of the switch?? Or do I try to find a switch with like multiple acc inputs?
I'm sort of new to this, so forgive me for my lack of knowledge here.
One last question: do I use a fuse to put in between the switch and battery connection, and IF so, what type of fuse and what size?
Thanks in advance for any advice!
oldspark 
Gold - Posts: 4,913
Gold spacespace
Joined: November 03, 2008
Location: Australia
Posted: October 18, 2014 at 6:22 PM / IP Logged  
Ground the lights.
Since they are 40W (each?) and hence 160W & hence over 10A I'd suggest a relay.
The +ve goes to 87 of the relay with 30 to the battery +12V with a fuse near the battery to protect the wiring & the relay. (I'd probably size for at least 15A and use a 15A fuse.)
Being LEDs they are probably voltage insensitive (ie, don't vary output above (say) 9V or 11V etc) and hence any +12V tap (instead of battery +12V) may be easier - provided it can handle the extra 10-15A.
Relay 85 to GND and 86 to any suitable +12V on switch. The switch's +12V comes from whatever applicable source - eg, beam, hibeam, ACC.
redneckincanada 
Member - Posts: 4
Member spacespace
Joined: October 18, 2014
Location: Manitoba, Canada
Posted: October 18, 2014 at 8:41 PM / IP Logged  
oldspark wrote:
Ground the lights.
Since they are 40W (each?) and hence 160W & hence over 10A I'd suggest a relay.
The +ve goes to 87 of the relay with 30 to the battery +12V with a fuse near the battery to protect the wiring & the relay. (I'd probably size for at least 15A and use a 15A fuse.)
Being LEDs they are probably voltage insensitive (ie, don't vary output above (say) 9V or 11V etc) and hence any +12V tap (instead of battery +12V) may be easier - provided it can handle the extra 10-15A.
Relay 85 to GND and 86 to any suitable +12V on switch. The switch's +12V comes from whatever applicable source - eg, beam, hibeam, ACC.
Thanks for the reply.
What kind of relay do I purchase, and what does "87, 30, +ve and 86" mean?
Yes they are 40W each. So 160W total, correct.
Also they say they have a operating voltage of 9-32V each if that helps any.
oldspark 
Gold - Posts: 4,913
Gold spacespace
Joined: November 03, 2008
Location: Australia
Posted: October 18, 2014 at 10:27 PM / IP Logged  
See the Relays tab at the top of this page. The numbers refer to a DIN or Bosch/Hella etc numbering system that was/is popular - especially with common automotive "cube" aka mini-DIN type relays.
I prefer using "circuit" type diagrams where one can see the relevant terminals involved and hence match the relay to whatever you want (most automotive relays have diagrammatic legends on their body, else datasheets can be used) and hence I ignore relay terminal numbering. (In fact despite decades in automotive electrics & relays I only [i[finally learned that 85, 85, 30, 87 & 97a numbering after joining th12volt.)
85 & 86 (or 2 & 1 as below) are merely the relay coil. (With 86 (or 1) being the more positive by convention tho only important if the relay incorporates a diode to prevent voltage spikes - something I prefer to do using external diodes so I can use any "plain" relay {and ignore coil polarity}.)
30 & 87 (or 3 & 5 as below) are the independent HEAVY contacts (switch) that connect the loads - eg, fused +12V to lights. (86 is the aka NO = Normally Open contacts, ie normally open as found when boxed on a shelf. 87a (or 4 as below) (if fitted) is the NC = Normally Closed contact - it is normally (when boxed or NOT energised) connected to 30 (or 3 as below).
30 (or 3) connects to 87 (5) when the relay coil is energised.   
You may prefer to use the smaller micro-DIN relays (~half the width of the ~1" cube relays) in which case the numbering is probably useless - ie, 86 & 85 are 1 & 2 respectively, & 30 & 87 (&87a if fitted) are 3 & 5 (& 4) respectively.
Or any other suitable relay.
Your relay could be a common 30A rated automotive cube (mini-DIN) type, or a micro-DIN (half cube?) tho micro-DINs are usually rated for less than 30A - eg, 16A or ~22A being typical.
Tho an SPST relay (aka 4-pin or on-off) is all that is needed, consider using an SPDT (aka 5-pin or change-over). Many do that because they are (usually) the same price and will plug into the same relay bases so one spare part suits both SPST & SPDT relay applications (assuming contact current ratings and perhaps terminal sizes are suitable).
Tho I keep thinking I'll link instead of repeating former stuff, since my washing isn't quite yet finished...
An example of my Design approach:
Determine the maximum current draw. In this case I'd assume 160W @ 9V (since LEDs can be "constant power" loads unlike traditional loads which were resistive else perhaps max or constant current). Hence from P=VI, I=P/V = 160W/9V = 17.7A. Hence a 20A or higher rated relay & wiring & fuse.
Normally fuses & relays (and maybe wiring) is designed to normally run at no more than say 70% of rating, hence suggesting a 17.7A/0.7 = 25A "design" (fuse & relay & wiring) tho in this case how often will you run with a 9V supply?
Hence IMO wiring & fuse a relay with at least 15A rating will suffice. EG - at 12V, 160W = 160W/12V = 13.3A but if the alternator is charging at say 14V it's 160/14 = 11.4A so a 15A design should be ok.
I will generally oversize my wiring (eg, 20A or 25A in this case) and use a 30A cube relay else a micro relay with a minimum 15A rating, preferably 20A or more.
My wiring & relays etc are often rated far higher than what is needed but I'll use a fuse commensurate with the load, hence minimising short circuit currents. I'll oversize to minimise voltage drops (not important in your case) or to allow future expansion whereby I merely have to upgrade the fuse instead of the entire distribution.
The fuse must be rated no higher than the lowest rated distribution - eg, 16A relay with 25A wring means a max 16A fuse, hence a 15A fuse.
Note that the fuse is to protect the distribution in case of some downstream short (to GND) and hence should be as close to the battery +12V (or whatever +12V take-off you use) as possible or practicable. The fuse IS NOT to protect the LED lights.
You should find similar advice with examples here on the12volt.   
(The washing just finished. That spares you from more verbiage.)
redneckincanada 
Member - Posts: 4
Member spacespace
Joined: October 18, 2014
Location: Manitoba, Canada
Posted: October 18, 2014 at 10:40 PM / IP Logged  
oldspark wrote:
See the Relays tab at the top of this page. The numbers refer to a DIN or Bosch/Hella etc numbering system that was/is popular - especially with common automotive "cube" aka mini-DIN type relays.
I prefer using "circuit" type diagrams where one can see the relevant terminals involved and hence match the relay to whatever you want (most automotive relays have diagrammatic legends on their body, else datasheets can be used) and hence I ignore relay terminal numbering. (In fact despite decades in automotive electrics & relays I only [i[finally learned that 85, 85, 30, 87 & 97a numbering after joining th12volt.)
85 & 86 (or 2 & 1 as below) are merely the relay coil. (With 86 (or 1) being the more positive by convention tho only important if the relay incorporates a diode to prevent voltage spikes - something I prefer to do using external diodes so I can use any "plain" relay {and ignore coil polarity}.)
30 & 87 (or 3 & 5 as below) are the independent HEAVY contacts (switch) that connect the loads - eg, fused +12V to lights. (86 is the aka NO = Normally Open contacts, ie normally open as found when boxed on a shelf. 87a (or 4 as below) (if fitted) is the NC = Normally Closed contact - it is normally (when boxed or NOT energised) connected to 30 (or 3 as below).
30 (or 3) connects to 87 (5) when the relay coil is energised.   
You may prefer to use the smaller micro-DIN relays (~half the width of the ~1" cube relays) in which case the numbering is probably useless - ie, 86 & 85 are 1 & 2 respectively, & 30 & 87 (&87a if fitted) are 3 & 5 (& 4) respectively.
Or any other suitable relay.
Your relay could be a common 30A rated automotive cube (mini-DIN) type, or a micro-DIN (half cube?) tho micro-DINs are usually rated for less than 30A - eg, 16A or ~22A being typical.
Tho an SPST relay (aka 4-pin or on-off) is all that is needed, consider using an SPDT (aka 5-pin or change-over). Many do that because they are (usually) the same price and will plug into the same relay bases so one spare part suits both SPST & SPDT relay applications (assuming contact current ratings and perhaps terminal sizes are suitable).
Tho I keep thinking I'll link instead of repeating former stuff, since my washing isn't quite yet finished...
An example of my Design approach:
Determine the maximum current draw. In this case I'd assume 160W @ 9V (since LEDs can be "constant power" loads unlike traditional loads which were resistive else perhaps max or constant current). Hence from P=VI, I=P/V = 160W/9V = 17.7A. Hence a 20A or higher rated relay & wiring & fuse.
Normally fuses & relays (and maybe wiring) is designed to normally run at no more than say 70% of rating, hence suggesting a 17.7A/0.7 = 25A "design" (fuse & relay & wiring) tho in this case how often will you run with a 9V supply?
Hence IMO wiring & fuse a relay with at least 15A rating will suffice. EG - at 12V, 160W = 160W/12V = 13.3A but if the alternator is charging at say 14V it's 160/14 = 11.4A so a 15A design should be ok.
I will generally oversize my wiring (eg, 20A or 25A in this case) and use a 30A cube relay else a micro relay with a minimum 15A rating, preferably 20A or more.
My wiring & relays etc are often rated far higher than what is needed but I'll use a fuse commensurate with the load, hence minimising short circuit currents. I'll oversize to minimise voltage drops (not important in your case) or to allow future expansion whereby I merely have to upgrade the fuse instead of the entire distribution.
The fuse must be rated no higher than the lowest rated distribution - eg, 16A relay with 25A wring means a max 16A fuse, hence a 15A fuse.
Note that the fuse is to protect the distribution in case of some downstream short (to GND) and hence should be as close to the battery +12V (or whatever +12V take-off you use) as possible or practicable. The fuse IS NOT to protect the LED lights.
You should find similar advice with examples here on the12volt.   
(The washing just finished. That spares you from more verbiage.)
Very useful info oldspark, thanks so much!
Here are links to a relay that (I think) would suffice:
http://www.ebay.ca/itm/Cube-Relay-24-Volt-DC-20-Amp-Continuous-duty-/261577349788?pt=LH_DefaultDomain_0&hash=item3ce7399a9c
Is this the right one I need?
redneckincanada 
Member - Posts: 4
Member spacespace
Joined: October 18, 2014
Location: Manitoba, Canada
Posted: October 18, 2014 at 10:41 PM / IP Logged  
Also what is the minimum AMP rating my toggle switch will have to be?
16A??
oldspark 
Gold - Posts: 4,913
Gold spacespace
Joined: November 03, 2008
Location: Australia
Posted: October 19, 2014 at 3:36 AM / IP Logged  
Is your Pathfinder 24V? That's a 24V relay.
And it's bluddy expensive - typical cube relays are only $3-$4.
It does include a diode which shouldn't be necessary besides which we usually like to add our own if required - namely a 1N4004 or 12N4007 diode that costs ~$0.05c in bulk else maybe 20c each. (Maybe the diode accounts for the relay's high cost? - I believe inbuilt-diode (relay) manufacturing runs are quite small these days.)
Relay coils are typically well under 1 Amp except for (say) 100A & larger rated relays.
Your linked relay may be a 200mA coil - ie, "24 Volt DC 20 Amp Continuous duty 0 332 209 204 . continuous duty type power relays 24 volt DC,20 amp" but that could be a mistype and repeat of its 20A rating.
But typical 12V cubes have coil currents up to 250mA (or ~half that if 24V) so almost any switch will handle it.
[ FYI - Ohm's Law V=IR so a 250mA relay coil resistance is R=V/I = 12V/.25A = 48 Ohm tho usually higher if using 13.8V or 14.4V for the coil rating. Usually 12V automotive 30A to 60A rated relays have coil resistances of about 60 Ohms or more. ]
Note that that is the beauty of relays - a small current/switch controls a MUCH higher current. Hence a bigger choice of (smaller) switches.
And of course the limited need for high current cable. IE - thin low current wiring to & from the switch to the relay coil, and fat HIGH current wire from power source (eg, battery +12V) via fuse thru the relay to the load.
In combination the above means remote control with short power wiring - typically the relay is placed between the source & load to give the shortest heavy run, hence max voltage to the load (lower voltage drop) with less weight & cost etc. And no (long) heavy wiring into the cabin.
And since I've pulled in my 3 loads of dry washing...
I don't like high currents thru switches - eg, more than a few Amps. In part that's because I use old vehicles (my current present roadrunner is a mere 49 years old) and I have noted how hot switches get with age. (As to foot-mounted dip switches that decide to melt onto bare feet... led light bar on my suv - Last Post -- posted image. )
All my beams are via relays.
I even used (micro-DIN) relays for my retro-fitted electric windows (easier than replacing the original worn mechanism) despite the motors only being 2-4A (peak at 9-13A at ends) and using a 25A rated switch in the doors for their physical rocker-paddle size.
But that means I can add additional low-current switches in alternate locations OR to select the power source (locked; +12V direct; IGN or ACC) and even have them CPU controlled (namely once I get around to building a PICAXE 08M2 controller for auto opening & closing, and soft start for fine adjustments).
But now it's time for Dr Who. I can't miss that!

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