Adding an always on 12V female outlet?

Hi,

First excuse the ignorance.. and here it goes....
2006 Tacoma SR5 4.0 Double Cab 2 wheel drive.
I want to add an always on 12V outlet.. Probably using an "add a fuse kit.." but I can't figure out a couple of things.. I bought the 12V outlet already and it has 2 wires... one positive and one negative.. I figured the positive would go connected to the "add a fuse kit" but than where does the negative go to? I thought somewhere in the chassis of the truck but want to make sure.
2nd, how do I find out witch one of the fuses already in the truck will give me the "always on".
There are also a good amount of empty fuse spots.. is there anywhere I can find out what they can be used for. .. I have the owners manual and all that shows is where the fuse box is.


Thank you.

 

The black will connect to the ground (chassis, whatever).

As far as always on fuses, I'm not sure about 2006, but in first gens, your best bet is one in the engine bay. The accessory plugs are usually rated up to about 15 or 20 amps, so unless the feed line is beefy enough to handle the extra power, I'd stay away from the add a fuse (the only time I'll use add a fuse is to power a relay). I'd be more willing to suggest you tap into an existing accessory plug and run off that just so you dont overload your wiring. If you're planning on running a higher amp item off the plug, run a dedicated line from the battery or the fuse box.

The only way to know for certain is to get a tester and see what has power and what doesn't with the ignition off. For just seeing what has power, a simple test light will work fine.

 

Thanks for the reply, I am going to be using this to connect a cellphone to use it as a GPS lojack. Idea that I found in this forum and only for that use. the phone is going to be somewhere under the dash.
and again sorry for the ignorance, but when you say "tap into an existing accessory plug" what
does it mean? are you talking about the empty fuse spots? if that is what you are referring to, any ideas of how I can find out witch one I can use
Just in case I'm posting a pic of the fuse box... hope it works, haven't uploaded on this site before.



Thanks again

 

Well, if you're doing it for a low jack type of thing, you dont want it to be easily disconnected anyway. In fact, you dont even want anyone to suspect that anything is different than factory in the fuse box, so I would leave the fuse box alone.

I doubt the draw on the phone will be all that power consuming, but it is something you need to find out on before you really continue. If it draws too much power, you may not want it to be drawing from the battery while off (instead using its own internal battery).

If it doesn't use all that much power, what I would suggest you do for this is to go buy some wire taps. They aren't the best, but since this isn't really a critical device, you'll be fine in using them.

Anyway, disassemble your dash enough to get to the back of the existing accessory plugs. Each one should have two wires, just as your new one has. Just use the wire tap to connect the new accessory plug into each of the existing wires. They'll be marked power and ground somehow, although the one going straight out the back will be power. You'll probably have to separate them a bit and/or remove the conduit.

Just make sure that the new plug doesn't have any chance of shorting out if it shifts or settles while driving (protect the power side connection with tape, shrink wrap, and/or a coating of some type.)

Also, for the phone itself, make sure to turn off the ringer, as nothing quite gives it away like a wrong number calling in...

 

Check out my electronics basics thread (link in my signature). It might have some useful info for you if your putting together your own circuit.

 

Most cell phones have several days of standby time, so if you are only using it for LoJack, then you won't need an always on 12v source, and you can tap off either power outlet on the center of the dash.

 

Thank you all for the replies... and have one more question..
according to the owners manual.. says use for 12v/120w max..
does this mean 12v = 120w's or is the 12v a minimum and the 120w a maximum?
I'm trying to find out the conversions on google. but keep finding way too much info. and nothing straight fwd...
reason why I'm asking is if the power outlet that I have available is used for my regular cellphone... would it be safe to tap into that one for the other cell phone outlet.. or would the lighter outlet be a safer choice? ...
Just looking at choices, trying to keep it simple but most important.. safety for the electrical system of my Toy..
all I know about electrical systems in a car is that they can be a huge problem if something goes wrong..so, I'm trying to avoid frying anything.


Thanks again.




Thanks

 

Watts and Volts are two completely different things. Together, you can use those to determine amps. 120watts/12volts = 10 amps.

10 amps is really heavy to leave connected all the time, granted it wont be running at that rate all the time, it really is way too much to leave connected directly to the battery. Your battery would be dead in minutes to hours with a constant 10 amp draw on it.

If you're really serious about leaving it connected all the time, you need to determine how much energy the device is really going to use and if its too much, rethink things quite a bit.

But as stated earlier, cell phones will usually last half a week or more between charges if they aren't used. No clue how a gps will affect that time, but a lot of cell phones also have aftermarket extended batteries as well.

The main problem you're going to have with constantly charging a cell phone is that most will go into a sleep mode when not plugged in and inactive. When it is plugged in, it no longer thinks it needs to worry about the sleep mode, so wont worry about conserving power, using whatever excess power isn't being used to charge the phone. Even my cheapy cell phone, when its plugged in, has the screen on all the time (not backlit, but still on); while unplugged, the screen turns off after a certain amount of time.


To me, 10 amps is just way too high to piggy back off another circuit, even if it is just a spike once in a while. I'd be running a dedicated line, but since 10 amps is also way too high to run with the ignition off, I'd also wire up a relay to only charging while the ignition is on.

 

Here's the thread I'm referring to: http://www.tacomaworld.com/forum/technical-chat/103969-electronics-basics-reference.html

I have a link to it in my signature too.