take a look at my dual battery post i just put up in this section, may give you some ideas regarding fuses, and plenty of accessory options.

 

This alone is not enough. If the wire over heats and catches fire. The plastic will only be fuel for the fire.

 

Yes, that would work well. If you ran both power wires to that connector, then you wouldn't need two of them, but you would have to pick a fuse that was capable to handle the current draw of both heated seats. Now if you used 2 separate fuse box connections, and ran each power wire to each, then you would need 2 and that would probably be your best option. I believe M8 and M9 are for heated seats, so wire one seat to M8 and the other to M9 with each having their own fuse adapter.

If you're using relays, then you would also need fuses for the other wires that power the relay, but you probably wouldn't need relays if you use separate M8 and M9 power connections. Each of those connections should be able to handle 20 amps or more each, making the relay unnecessary and over complicating things.

P.S. Sorry, just realized you're wiring lights. If you're wiring only 2 lights at 85 Watts each, then you wont need relays....given you connect each light separately to the M8 and other to M9. Given POWER is 85 Watts P=I*V.....85=I*12Volts => I= 7 Amps. So each light will draw about 7 amps of current. So you "Might" actually be ok to connect 2 lights to M8 and then 2 to M9, without having to use a relay, which would then draw 14 amps from each fuse box connection, and you would probably use a 20 amp fuse on that fuse adapter.

 

Using relays might seem complicated to some. But it is necessary. Most switches are rated for only 15 amps. Even though the OP is anly intending on applying a 14 amp load, it's still almost full capacity of the switch. The idea of using a relay is to keep load carrying devices out of the cabin. Also, using just ( 1 ) control circuit to feed all your switches eliminates installing a power source to each individual switch. Yes there are many ways to do this job. And there are many opinions on how to do this job. But there are very few ways to do it right.

 

Why don't you provide him with a wiring diagram then, instead of quoting all my posts and criticizing them? Heck, provide him with a schematic using MosFets instead of relays if you like, so he won't have to worry about relay mechanical failure.

I don't know how many lights he is or isn't using. I was giving him some options and information, so he could make his own educated decisions. Feel free to take the lead and do the same.

 

I'm just trying to use my 30 + years of electrical experiene to help someone. Because I enjoy using my skills to help others. If you think that you know more about power distribution and control circuits than me. Then prove it and I will gladly back out. In the mean time, If you listen to what I have to say. You may learn something too! "MosFets"? Even you electronics training should reflect something about load carrying devices and non-load carying devices.

 

Switch blowing up? No, there is no issue going direct to the battery however make sure you put a fuse between it. I have wired my WARN HID direct to my battery, even the 'light' wire is going straight to the battery, no issues at all.

 

Mark. I sure hope you can take this better than Rednroll. The only concern with having a switch powered directly off of a batery would be the possibility of accidently leaving the switch on. A dead battery is no fun. Switches can fail catastrophically if you power the load directly from the switch without a relay. But they would have to be severly overloaded. More than likely, one would just get to hot and melt down. This is one of the reasons why it is desirable to keep the load carrying devices out side of the cabin. Your system most likely came with a relay.

P.S If you throw in enough MosFets on you lighting system, you may also be able to tune in you favorite radio station.

 

It sounds like with your 30+ years of experience, you need to come out of the dark ages and get up to date.

You mention all the good things of a relay, but fail to mention any of the bad things. In all essence a relay is a "switch". So all the bad things you mention about a switch also apply to a relay. A relay is a mechanical device which has metal moving parts and a spring. It is therefore susceptible to things like moisture, dirt and corrosion....3 things that are very present in an automotive environment. A relay is able to pass high amounts of current through this mechanical device. Have you ever connected a wire to a battery which was connected to a circuit which draws a lot of current? I would hope you have in your 30 years of electronics. What did you observe? Probably an spark ARC right? What do you think happens in a relay circuit when the relay switch gets closed? An arc spark, in a device which is enclosed in plastic. If you've used a relay with a clear housing, you can even see this spark occur when the relay closes. Sparks combined with plastic....what's that open the potential of happening? FIRE!!! Starting from inside the relay. Did I mention there's also a spring mechanism inside of that relay? So what happens with a spring when you drive down a bumpy road? The spring bounces, causing the switch to momentarily open and close....now your lights are flashing on an off driving over bumps....and guess what? The whole time that's happening arcing is happening inside of the relay.

When you pass high amounts of current through a wire what happens to that wire? The wire heats up. What is the part that opens/closes inside of a relay? A metal piece of wire which heats up just the same. What happens when you put a hot object into a colder environment, which often occurs in a automotive application? It causes condensation to occur inside of that part. And what is condensation? WATER. What happens when you mix electronics and water together? Nothing good....it causes short circuits, and inside of a relay it causes corrosion to form between the metal parts.

Since the relay is a mechanical device made of metal moving parts, what happens to any metal part that moves over time? It wears out and becomes weak....again causing the relay to fail.....and additionally increasing the chances of more arcing to occur inside the relay, since those parts become weaker and even more susceptible to "vibrations".....which are VERY present inside of a vehicle.

And you want to put these relays inside of the engine compartment don't you? An environment which is surrounded by heat, moisture, and dirt the most. The exact kind of environment that causes failures within the relay to most likely happen.

Sure a relay will work great after it's 1st installed.....now what happens to it over time due to being used in that engine compartment, surrounded by all those elements I just mentioned? It fails and it can fail in a manor that causes fire or just makes it so your lights don't work when you most likely need them.

Sure Relays were used all the time 30 years ago in automobile electronic applications. EVERY automotive manufacturer has moved away from using relays for the EXACT same reasons I mentioned. What are they using instead? MOSFETS. An electronic device which is able to have a small signal voltage turn on/off and pass a large current voltage signal. The EXACT same application that a RELAY does. Yet, a MOSFET has NONE of the mechanical properties that a relay has, and can serve the same purpose as a relay, yet is resilient to all the automotive environment elements that can cause a relay to fail, since it's made from silicon with no metal moving parts.

Maybe 30+ years ago MOSFETS where only used in "radios", but today they're a much more capable device, which is able to handle high amounts of current being driven through them.

So take your 30+ years of electronics experience and shove it up your ass, jack-ass. You don't know as much about electronics as you "think" you know, and you certainly have no experience understanding what can and will happen to certain electronic devices like a RELAY in an automotive environment, because no one with an electrical engineering background who has worked in the automotive industry would EVER suggest using a relay in an automotive environment except some electronics hack, given the fact that there's a much more robust and safer device that could be used instead.....and weren't you the one who said "there are many opinions on how to do this job. But there are very few ways to do it right. Yeah, so do the job RIGHT then Jackass.

He's wiring to the M8/M9 fuse sockets which are turned on/off through the ignition key.....and where those connections are most likely turned on and off through a Mosfet by the way. So your comments about accidentally leaving the switch on and killing the battery doesn't apply, unless he also forgets and leaves his key and ignition turned on also.......additionally, the relay is able to do the same thing when corrosion starts to form, or start to become weak due to vibrations....and corrosion WILL start to form inside of a relay over time and the spring inside of the relay WILL become weaker over time, causing the relay to close the switch inside of itself by itself.

Once again, ALL the things you mentioned about a switch can also occur with a relay.....because a relay is a switch.....just one where a smaller voltage is applied to a coil of wire, which causes a magnetic field to open and close that switch.

 

This post just got interesting...

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