isbjorn Posted January 10, 2010 Share Posted January 10, 2010 Hi. Im installing three xenon lights in the front and is about to do the wiring tomorrow. Ofcourse I can hijack the headlight cable and run it to a new relay and some fresh wires straights from the batteries. But is there a recommended place to steal the power (or should I connect it by the main headlight relay?). I assume there is a land rover RAV instruction or something on installing extra lights in the front, but I dont have it. The best would be if there is a good place to hijack the power in the engine bay and place the relays there. Feels stupid to steal the power if there already is a prepared solution from LR. Or what do you think? thanks 110, td5 99. Quote Link to comment Share on other sites More sharing options...
tuko Posted January 10, 2010 Share Posted January 10, 2010 Hej Isbjorn, The relay should have direct power from the battery (fused) and the switch would provide the on/off power supply. Todd. Quote Link to comment Share on other sites More sharing options...
western Posted January 10, 2010 Share Posted January 10, 2010 attached might help. Quote Link to comment Share on other sites More sharing options...
petethepilot Posted January 10, 2010 Share Posted January 10, 2010 Take the power supply directly from the alternator to the relays, not from the battery. You get more volts = brighter lights, less strain to the battery, shorter cables. But don´t forget 30Amp fuses and thick enough cable! Quote Link to comment Share on other sites More sharing options...
isbjorn Posted January 10, 2010 Author Share Posted January 10, 2010 Good point about the alternator as long as the engine is running. But what happens if It isn't? (It should be but anyway just for the question), and should I run in the earth straight to the batteries or the frame? Quote Link to comment Share on other sites More sharing options...
petethepilot Posted January 11, 2010 Share Posted January 11, 2010 When alternator is not running, the power comes from the battery via alternator. Always ground to the chassis, shortest way, and remember to use as thick wire as you are using for the lights. Use at least 2,5 mm2 wire. But if you are using 100W or more powerful bulbs you might go to 4mm2. And remember to use fuse in power intake wires, at least 20Amp, but again if you are going to use those high wattage bulbs (I would, because they really make a difference) use 25 or 30Amp fuses. The secret in using thick wire is that you minimize the power loss as heat to the bulbs. In practice you will get the same current now to the lights, than the power output from the alternator, which can be as high as 14.7V. If you take the power from the battery, you will get only about 12,3V or something. If you want, you can calculate the power gain in %. That´s proportionate to the brightness of your bulbs (also longevity, witch is the downpoint). Quote Link to comment Share on other sites More sharing options...
isbjorn Posted January 11, 2010 Author Share Posted January 11, 2010 perfect. thanks. Quote Link to comment Share on other sites More sharing options...
LandyManLuke Posted January 11, 2010 Share Posted January 11, 2010 Don't wire grounds direct to the body/chassis, you are inviting voltage drops due to high resistance joints caused by corrossion and dirt etc. There's nothing wrong wiring direct to the battery, if the wiring is done properly the lights will see the full voltage. In fact, I think it is much better, as a rule to take extra wiring, from the battery. For starters, the output stud on the alternator is not intended to be used as a junction box! Put it this way, it would be quite possible to wire enough accessories direct to the alternator such that you would end up drawing more than the alternator wiring is capable of, with the engine off. It's very easy to avoid this situation - don't wire to the alternator! Fuse sizing is not guess work or rule of thumb. You can work out the current draw, given the power (in Watts), and the fuse should be rated the next size up. The wire should be rated higher again. Quote Link to comment Share on other sites More sharing options...
isbjorn Posted January 11, 2010 Author Share Posted January 11, 2010 Well, on my previous def it was wired straight to the second battery and earthed in the chassi and that was 5x100w lights. Now its three xenon 55w so it shouldn't need that heavy stuff. And I also like the ide of putting the spare lights on a separate battery from the starter. Quote Link to comment Share on other sites More sharing options...
tuko Posted January 12, 2010 Share Posted January 12, 2010 "three xenon 55w" You'll have to keep us updated on these lights, especially the light output. I see on Blocket that the price has come down on those babies making them more appealing. I second that the power supply is from the battery, there is a recent thread where one person tells us how his alternator died from using it as a power supply for his acessories. If the alternator is up to sniff, it'll supply 14.4V to the battery, so power wise the battery has as much as the alt. produces therefore doesn't justify the connection at the alt. Quote Link to comment Share on other sites More sharing options...
isbjorn Posted January 12, 2010 Author Share Posted January 12, 2010 I will. have to build a lightbar first.. costed ruffly 100EUR each. Quote Link to comment Share on other sites More sharing options...
petethepilot Posted January 12, 2010 Share Posted January 12, 2010 "three xenon 55w" You'll have to keep us updated on these lights, especially the light output. I see on Blocket that the price has come down on those babies making them more appealing. I second that the power supply is from the battery, there is a recent thread where one person tells us how his alternator died from using it as a power supply for his acessories. If the alternator is up to sniff, it'll supply 14.4V to the battery, so power wise the battery has as much as the alt. produces therefore doesn't justify the connection at the alt. Yes, but you will newer get more out of the battery than it´s nominal voltage. And make one draw from the alternator to the divider, so there are no extra wires connected under the alternator bolt. Only one with sufficient strenght cable. And Btw, the battery´s - is not a ground, you are grounding it to the chassis which is the ground. And for the functionality of the battery and all the appliances, all the grounding points must be clean and solid. Also the alternator will die if battery or the appliances it is trying to run are badly earthed or the battery is giving up and taking all the current up which alternator is giving. And of course you should calculate the power need so that you will not beef out your alternator. When we are building rally cars and seeking for the ultimate reliabilty and distortless electricity for everything, nothing is taken directly from the battery, everything is via alternator, and everything is grounded to the chassis with minimal lenght of sufficient wire. If the voltage from the alternator is too high or distorted as it sometimes is, it will be regulated for some appliances. And what comes to the fuses, I don´t guess, I know. Have been doing this for over twenty years and have some formal education to that also. Formula (Ohm´s law) = P=UxI, where P= output, U=voltage, I=current so for example 100W = 12v x 8,3333A 8,3333A = 100W : 12v. And if you want something to be effective, you don´t want to restrict it with too small fuses. Also wire thickness and lenght will have effect on the resistance, which means that some energy will be lost due to it´s transforming into heat. These are examples of wire sizes/fuse sizes: 1,5mm2 - 10A 2,5mm2 - 16A 4mm2 - 20A 6mm2 - 25A 10mm2 - 32A 16mm2 - 63A 25mm2 - 100A With this formula you can calculate the resistance if you will= R= U/I And for the last, it´s not the voltage which makes the damage, it´s the current (Amps). Battery is a storage of power for starting the car, not a power source. (well, not quite, but roughly generalized, you´ll get the idea.. Quote Link to comment Share on other sites More sharing options...
dwappat Posted January 12, 2010 Share Posted January 12, 2010 Isn't that formula "Watts" rather than "Ohm's" law? Yes, but you will newer get more out of the battery than it´s nominal voltage. And make one draw from the alternator to the divider, so there are no extra wires connected under the alternator bolt. Only one with sufficient strenght cable. And Btw, the battery´s - is not a ground, you are grounding it to the chassis which is the ground. And for the functionality of the battery and all the appliances, all the grounding points must be clean and solid. Also the alternator will die if battery or the appliances it is trying to run are badly earthed or the battery is giving up and taking all the current up which alternator is giving. And of course you should calculate the power need so that you will not beef out your alternator. When we are building rally cars and seeking for the ultimate reliabilty and distortless electricity for everything, nothing is taken directly from the battery, everything is via alternator, and everything is grounded to the chassis with minimal lenght of sufficient wire. If the voltage from the alternator is too high or distorted as it sometimes is, it will be regulated for some appliances. And what comes to the fuses, I don´t guess, I know. Have been doing this for over twenty years and have some formal education to that also. Formula (Ohm´s law) = P=UxI, where P= output, U=voltage, I=current so for example 100W = 12v x 8,3333A 8,3333A = 100W : 12v. And if you want something to be effective, you don´t want to restrict it with too small fuses. Also wire thickness and lenght will have effect on the resistance, which means that some energy will be lost due to it´s transforming into heat. These are examples of wire sizes/fuse sizes: 1,5mm2 - 10A 2,5mm2 - 16A 4mm2 - 20A 6mm2 - 25A 10mm2 - 32A 16mm2 - 63A 25mm2 - 100A With this formula you can calculate the resistance if you will= R= U/I And for the last, it´s not the voltage which makes the damage, it´s the current (Amps). Battery is a storage of power for starting the car, not a power source. (well, not quite, but roughly generalized, you´ll get the idea.. Quote Link to comment Share on other sites More sharing options...
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