Off road lighting amp questions
 

I'm looking to install 4x 27w LED lights on my 2011 F150. Not sure if the math is different for LED vs normal lights, but what amps should these use? I'm figuring 2-3amp range each? If so, would one standard 40amp foglight relay should be more than adequate, yes?

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Yes.

MGD

Great, so 1 relay it is. And 15amp fuse should be plenty off the battery then.

Next question... I'm hooking them up to a 5-pin rocker switch like the ones from Otrattw (link to wiring diagram here http://www.otrattw.com/wiring/F76a.pdf). I plan to mount it in the dash next to the dimmer switch--2011 F150... Where do y'all recommend for a good constant 12v power back there I could tap into, or it better just to run two lines through the firewall (one from battery for the switch, then one back up to the relay)? I suppose I could tap the fuse box but then still have to run the wire over to passenger side, so not much better..

Thanks!

Hey.

If yer usin' one o' them Carling switches form Otrattw, they are 20 amp-rated. You could, if you wished, safely dispense with the relay. Just a thought.

IF you are wanting these to have power regardless of ignition switch state -I'd run a fused supply direct form the battery. You can find existing grounds behind the driver kick panel.

IF you want to only have them active in acc/run, you will need to use a relay and tap off one of the acc fuses in the SJB with an Add-a-fuse as yer permissive. Main power (fused) still from the batt.

Don't have info on what is available in that immediate area as an alternate. Sorry. Someone else may, though. Or you can look here: http://www.revbase.com/BBBMotor/Wd (courtesy of Hagar).

good luck!
MGD

reeeeeeaally.... So i'd just run a fused line (prolly just a 15amp) from the battery to the switch, then back run one line back from the switch and split it to the 4 lights, and good to go? Interesting. It seems everyone constantly says to use always use a relay for these offroad lighting--but was never entirely sure why, as it does seem kinda unnecessary for these?

Thanks!

Yep.

Relay use if the lights are high current (e.g. halogens ) and/or numerous.

Relay use if you need to apply logic to the switching arrangement ( e.g hot-in-run trigger use ), or you are using another control input, or you are using a really purty, dainty switch.

Fer yours - a 20 amp switch will run that low-inrush, non-inductive load just fine, fer yer intended simple switching arrangement. Please DO confirm yer chosen switch DOES have that rating first, though.

Size the wire runs adequately. Fuse as close to the batt as possible to protect the entire run. Protect the wire in loom. Use automotive-grade wire.

MGD