Wiring up a 12v source, help needed

[HMP]

Ok, I bought some dual USB outlets and I have it, currently, hooked up directly to the battery - was a VERY easy routing job, there's a grommet right behind the battery that leads directly to the passenger's side footwell.
Cool, done. But now Im thinking of disconnecting and trying to wire it up to only power up when the car is turned on (or at least to the acc part). I dont want power running to the outlet all of the time, sometimes I dont drive this for a couple weeks at a time.

What options do I have? Do I try to tap into the power from the radio? Or where should I be looking to draw power and to ground to/at?

 

[Frack N Cylons]

Easiest is to hit a fuse on one of the fuse boxes that is only powered on when ignition is on.

Next would be to install a relay that is piloted off a device that is only on when the ignition is on. If the USB device will draw lots of current this is the way to go. If not, just do the first one.

 

[LeeMajors]

Amazon product ASIN B0742BZXC2

 

[Frack N Cylons]

The USB wall wart next to me draws 2.4A at 5.2vdc so 13 watts. At 12 volts you’re only drawing a little more than an amp. I’d just tap onto an existing fuse and call it a day.

 

[Djstorm100]

Those don't pull hardly any amps. Could use one of these, can get from auto parts. Tap in to a fuse that is 10+ amps.
Personally, I'd go the route of a relay and have wire from the ignition trigger the relay on.

 

[dbarale]

Amazon product ASIN B0742BZXC2

^^^^ This ^^^^

 

[HMP]

@LeeMajors that might be the easiest way then!
Next, for the ground, do I need to just hook the black/ground to the body or on a bolt/nut that's going to the body?

 

[recreationalhandgrenade]

Those don't pull hardly any amps. Could use one of these, can get from auto parts. Tap in to a fuse that is 10+ amps.
Personally, I'd go the route of a relay and have wire from the ignition trigger the relay on.

View attachment 482482

Ain't seen that before, that's a great idea

 

[HMP]

Easiest is to hit a fuse on one of the fuse boxes that is only powered on when ignition is on.

Next would be to install a relay that is piloted off a device that is only on when the ignition is on. If the USB device will draw lots of current this is the way to go. If not, just do the first one.

Sounds like what LeeM stated is going off what youre saying, next I'd need to find a fuse that, like you said, is only on when car is on. More research to come!

THANK YALL for the quick and awesome replies

 

[HMP]

Those don't pull hardly any amps. Could use one of these, can get from auto parts. Tap in to a fuse that is 10+ amps.
Personally, I'd go the route of a relay and have wire from the ignition trigger the relay on.

View attachment 482482

So what Im using is 2 at 3v, if I remember right
Am I better going to a 15 or 20A fuse?

 

[LeeMajors]

@LeeMajors that might be the easiest way then!
Next, for the ground, do I need to just hook the black/ground to the body or on a bolt/nut that's going to the body?

Yes

 

[LeeMajors]

So what Im using is 2 at 3v, if I remember right
Am I better going to a 15 or 20A fuse?

Probably. But I think all the wiring to the fuse box is the same size in.

 

[Frack N Cylons]

So what Im using is 2 at 3v, if I remember right
Am I better going to a 15 or 20A fuse?

It looks like @LeeMajors doodle uses the existing fuse for the existing circuit and you add a new one for the new circuit. You don’t need more than like 2 amps or so on the fuse. Tell us what device you’re running and it should show on the box the current draw. USB by its nature is a 5v output and I’d be surprised if it the device drew more than a few amps at 5v. Push that up to 12v and you’re drawing less than an amp and a half.

@LeeMajors i like that doodle, I’ll have to remember that one. Pretty cool.

 

[Jeppo]

Those fuse taps are what I used to install dash cams on our two Fords. That’s ABSOLUTELY the way to go. You need to be VERY attentive to put the original and new fuse in their correct positions. If you need help, come over. I’ll show you how to find which fuses are powered up only when the ignition is on. A big help will be if you Google around for a fuse box diagram for your vehicle.

 

[Button Pusher]

See if the radio harness has a connection for motorized antenna, when the car is turned off the antenna retracts.
You can tap into this if the car has not motorized antenna if the harness has the connection.

 

[hp468]

If you have an aftermarket head unit the blue wire by itself should be the remote wire used to tell an amplifier to turn on.

 

[HMP]

If you have an aftermarket head unit the blue wire by itself should be the remote wire used to tell an amplifier to turn on.

I do

As far as what Im, mostly, trying to power -a Garmin GPS unit. I dont recall the model number right now (and, honestly, Im laying in bed already for the night). But I'll look into it tomorrow

 

[HMP]

See if the radio harness has a connection for motorized antenna, when the car is turned off the antenna retracts.
You can tap into this if the car has not motorized antenna if the harness has the connection.

I do have the retractable antenna, but it might be disconnected currently (or maybe it doesnt work at all)

 

[Jeppo]

Look how sanitary and uncluttered it is with fuse taps.

 

[Jeppo]

First step, invest $4 in one’a these.

6/12V Circuit Tester with 5 ft. Lead

Amazing deals on this 6/12V Circuit Tester With 5Ft Lead at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

 

[Jeppo]

How did you sort this out?

 

[HMP]

Honestly, nothing yet. I spent most of yesterday at the lake. Heading to garage shortly

 

[Get Off My Lawn]

I’ve used open slots in the fuse box, using a meter, find an open slot that only has power with the key on, run the lead from the back & install an appropriate fuse.

The fuse adapter looks like a quick way to get up and going.

 

[GoWolfpack]

Amazon product ASIN B0742BZXC2

Well now I've ordered those. I hope you're happy.

 

[LeeMajors]

Well now I've ordered those. I hope you're happy.

Last pack I ordered was a 50 pack. Gave more away than I used.

 

[GoWolfpack]

Last pack I ordered was a 50 pack. Gave more away than I used.

Ordered a 10 pack of each size. Hopefully I'll only use a few.

 

[Jeppo]

Well now I've ordered those. I hope you're happy.

You will be when you use them.

 

[HMP]

Sorry for lack of replying here
I ordered what @LeeMajors suggested, but I got the ones for the larger fuses (about 3/4" wide, not the 1/2" ones)
Be here tomorrow.
Yall are awesome, yall help me, and others, out so danged much.

Also, unrelated, I just ordered an inflatable paddle board ha

 

[Jeppo]

I just ordered an inflatable paddle board ha

12 volt? 🤔

 

[HMP]

Fuse taps wouldnt fit with the factory cover for the fuse block
Thankfully the internet is full of people trying to do similar and I found a print that was an enlarged (taller) version of the cover.
Took a few attempts but it finally worked out. I have now gotten all of the supports out of it - that was a pain but, near the end, I figured out how to efficiently 'clean it up' of all the supports with some needle nose pliers. Worked well. I fought for ten minutes with it, even broke out the dremel. In the end some pliers were the ticket.
Anyways, right now I have applied some primer to the piece, trying to build up/into the crevices a bit. Will apply a few coats then sand smooth and paint. I know, it wont really be seen, but this is also a way for me to try this method of 'smoothing out' 3D prints.