Second 12v (C. Lighter) wiring

[sen2two]

Im installing a second cigarette lighter to be able to run some things like a lap. another reason is i have no radio in my car for the weight reason, along with gauges, switches, ect, are in the spot where a radio would normally go. but since i drive this car to meets and work sometimes. i would like a radio. so i created a cheap simple removable set up. it consists of ordinary 110v computer speakers (high quality with good sounds/bass). An I pod and an inverter that simply plugs into a 12v cigarette lighter and converts into 110v power. i already tested it out in another car and worked great. and the speakers sounded like the car had an exspensive music system, lol...

but the cigarette lighter in my car dosnt work. tried tracing out the problem with no luck. either way, i dont want to have the inverter sitting there bumping my fist when i shift. so im wanting to install a second one in a remote location.

when i tryed wiring it strait to the battery so it works with the car off or on, it just keeps popping the 10amp fuse within the inverter. i thought i could just wire it srait to the battery for 12v power, and ground it.

what am i missing here???

[vex]

Originally Posted by sen2two

when i tryed wiring it strait to the battery so it works with the car off or on, it just keeps popping the 10amp fuse within the inverter. i thought i could just wire it srait to the battery for 12v power, and ground it.

what am i missing here???

I'll give you a little hint: how many amps does your battery supply?

[djmtsu]

My FC has I think 4 unused slots in the Fuse box inside the car. I use one of those fuse kits that has a wire lead coming off for 12v supply. I use another like that for the gauge illumination. Like this:

[TitaniumTT]

There's a 12:1 ratio of what an inverter will draw. Take the Watts that your inverter uses, divide by 12, multipy by 1.1 and you'll have a good idea of how many amps you'll need. For instance, the 800W inverter that we just installed in my partners MS6 required a 70 something AMP fuse and we ran a short length of 8ga wire.

A 10A cig lighter will supply less than 100W of AC current

[sen2two]

my inverter is small and only puts out 100 watts. but its all i need to power the small speakers. and by your formula: 100 watts / 12 = 8.33 then mulitplying that by 1.1 = 9.16 amp fuse needed, so basically a 10amp inline fuse is needed before the lighter?

what i dont get is how does this lower the amps? a fuse just breaks when a larger amperage passes through it. so how does the large amperage from the battery convert down to a smaller amperage to not blow all the electrics in the car?

im still in the learning process for car electronics, i been neglecting it for years...

[TitaniumTT]

Because you're not pulling the amps through all the circuits. Start studing wiring diagrams and you'll see how the current flows and why only the circuit being loaded is the only one being blown as opposed to all the others. It's pretty logical. There is just alot of math and schematics and diagrams to go through when learning this stuff.

[sen2two]

so i was using pure colombian coke instead of cut down snortable coke... i get it, lol

you reccomend using a 12v source from the fuse panel as djmtsu suggested to run the cigarette lighter power? or basically any other 12v source that is not directly from the battery...?

[TitaniumTT]

No

I don't like doubling up on circuits like that. If you can trace back the wire from the source that you're tapping into and make sure that the wire is of suffiecent size and completely free of corrosion then sure, it's safe. But are you willing to completely dissasemble the harness and fuse box to check everything? If not, than think about what you're asking that poor wire to do. At the ripe young age of 20+, you want a 16ga wire to power whatever the factory wanted it to, than you want to add another 10A draw to it? I smell a fire in the future

Short of doing that I pull power from unused wires located in the harness, again, assuming it's of the proper size etc etc. For example, use the stereo power source if you're not using a raido. I think it's a 15A fuse and from memory it's a W/Bl wire. Put a 10A fuse in the proper location in the fuse block and you're good to go.

Generally what I do whenever I have a project car or boat for that matter, is run one larger 2ga+ wire to a breaker directly off the battery. From there I generally go to a powerpost hidden somewhere and then off to the starter, the alt, the main fuse block. From that powerpost I can also run aux fuse blocks to power my own stuff that was never intended from the factory or just give it better power. Things such as a fuel pump, ign relay, power for the Motec etc etc etc.

[sen2two]

the one from my radio is used up to power my fuel pump and AI pump. i dont want to use it for anything else. I was thinking of splicing into the main power wire to my key ignition, since they are pretty thick wires. and use the same gauge from the ignition wire to my 12v socket with an inline 15amp fuse. then an equally sized ground wire.

[TitaniumTT]

Bad idea. You're over working wires. You should not tap into factory wires. The factory is not in the business of throwing away copper. They're going to use the the smallest wire possible to safely accomplish the task at hand. I thought I made that clear. Tapping a wire in use is a bad idea. Run a wire off the main battery to the load. The ONLY time that I will tap into a factory wire is to trigger a relay that pulls ~.25A. AND even then, I grabbed the wrong relay, one with a diode, and popped the factory fuse. Think about that.

Did you know that 75% of marine fires are caused by an overloaded electrical system. Do you know that most boat owners think that they can wire their own shit? Do you know that when I take on any electrical project I either will not touch it if someone altered the factory wiring or I strip everything out and start from scratch

[vex]

Some simple things can help you go along way:

1) Listen to TTT
2) Use a multimeter to know the voltages and resistance you're dealing with--remember: V=IR
3) The more resistance on the wire, the more heat. The more heat, the more likely fusing will occur, the more likely fusing occurs the more likely you'll short out near by wires.
4) Following voltage back to a relay usually is the best bet or wiring in your own relay directly off the battery would be ideal.

Wire in a simple accessory switched wire to the relay (this will close the circuit) and you'll draw 12v directly from the battery and you can specify what wire gauge to use. This also will allow you to put the proper fuse inline. When you turn the accessory off (the circuit is then opened), and your relay will keep your electronic device from drawing power directly from the battery.