modify my 12V outlet to stay on when car is off, i.e. help with car electronics

[CCCA]

I have a 2007 prius and on camping trips would like to have the 12V outlet stay on while the car is off to recharge the various batteries and lanterns that we use while camping.  In our Prius, the outlets go off when the car is turned off. 


I saw a kit that could be purchased here:
http://www.coastaletech.com/power_outlet_mod.htm


but when I emailed them, they said they were no longer selling this item.  there are also instructions on this page, that it seems like maybe I could recreate this item, but alas, I don't quite know what I'm doing.  I'm fairly handy (around the house, but not so much in the car) and if someone were to help me understand what's happening and what the power outlet mod is actually doing, I could probably figure out the rest of it.


Anyone have some more expertise in car electronics and the area around the fuse box?  The other option I was thinking about was to hook up another 12V outlet directly to the battery with something like this (https://www.amazon.com/Waterproof-Cigarette-Lighter-Socket-Charger/dp/B00O6WYGIA/ref=sr_1_5?ie=UTF8&qid=1491278640&sr=8-5&keywords=fused+12v+outlet), but then I have to route the wires to the dash (the 12V battery in the prius is in the trunk). 



Any help would be greatly appreciated. . .

[shawndoggy]

sounds to me like it's two posi-taps (one on a wire at the fuse box and one on the white wire of the 12v receptacle) and a wire between the two.  Seems super duper easy.

positaps here https://www.amazon.com/Posi-tap-Connector-16-18-Gauge-Wire/dp/B00389R8KU

then just get some 16 awg primary wire and connect the two taps and voila.

[lthenderson]

Why not just turn the key to the accessory position? I don't own a Prius but do they not provide power to the 12V outlet when in the accessory position?

[Spork]

I know nothing specific about Prius's (Prii?).  This is a generic statement about cars.  Working in and under a dash can sometimes be a royal f'ing pain in the ass.  If your outlet isn't particularly accessible, I might leave it alone... and install a second one somewhere out of sight.  I.e., up under the dash, inside a glove box, inside a center console, etc.    I've done a few simple fixes that required dash removal.... and that can turn a 10 minute project into an all day project.

[CCCA]

sounds to me like it's two posi-taps (one on a wire at the fuse box and one on the white wire of the 12v receptacle) and a wire between the two.  Seems super duper easy.

positaps here https://www.amazon.com/Posi-tap-Connector-16-18-Gauge-Wire/dp/B00389R8KU

then just get some 16 awg primary wire and connect the two taps and voila.

Cool! Your short comment was just enough for me to understand what is going on.   I just realized what a tap is in the website (it's a connection to an existing wire without cutting it).  Just one question though. The link you gave me is for 16-18 gauge wire.  Is that what you think is feeding the fuse box and the 12V outlet, or should I be trying to figure out what gauge wire is there?  I assume if you don't have the right gauge tap, it won't work very well or you might even cut the wire. 

Why not just turn the key to the accessory position? I don't own a Prius but do they not provide power to the 12V outlet when in the accessory position?

Our prius has a key fob you insert into the dash, but no key.  You can turn on accessories (by pushing the power button on the car) but then lots of stuff turns on, which is distracting when camping.  Plus don't like leaving the key in the car for long periods of time (which is necessary to recharge our camping lantern or other battery electronics).

I know nothing specific about Prius's (Prii?).  This is a generic statement about cars.  Working in and under a dash can sometimes be a royal f'ing pain in the ass.  If your outlet isn't particularly accessible, I might leave it alone... and install a second one somewhere out of sight.  I.e., up under the dash, inside a glove box, inside a center console, etc.    I've done a few simple fixes that required dash removal.... and that can turn a 10 minute project into an all day project.

Thanks for the warning.  It sounds like it's not terrible from the description online (they say 15 minutes).  So I'm going to go for it.

[shawndoggy]

Cool! Your short comment was just enough for me to understand what is going on.   I just realized what a tap is in the website (it's a connection to an existing wire without cutting it).  Just one question though. The link you gave me is for 16-18 gauge wire.  Is that what you think is feeding the fuse box and the 12V outlet, or should I be trying to figure out what gauge wire is there?  I assume if you don't have the right gauge tap, it won't work very well or you might even cut the wire. 

16-18awg is my best guess based on lots of crawling around under car dashes.

Those positaps I linked to are pretty accommodating and would (I think) work with say 14awg too.  No way will the lighter wire be bigger than 14 awg.  worst case you could probably widen the groove/channel that the wire will sit in a little bit to accommodate a larger wire.  You could always go 12-14awg positaps too, but they don't work well if they are "loose" on the wire (the channel the wire drops into centers the wire so that it can be pieced by a screw-in "poking device", so if the wire can wiggle a little bit out of the way, the poker may not poke the wire).

Don't use any other kind of tap under any circumstances than those positaps.  The positaps work very nicely and you will be able to revert to stock if you want to and nobody will be the wiser.  There are other crimp-type taps out there that are far less expensive that absolutely suck to work with and will cause you nothing but heartache. 

haha that's more than I ever thought I'd write about positaps!

[sokoloff]

Note that there's a Positap part number PT1218B that states it's good for 12-18ga wire. That will surely cover the span that you need to cover.

[shawndoggy]

Note that there's a Positap part number PT1218B that states it's good for 12-18ga wire. That will surely cover the span that you need to cover.

^^^ True dat.  I've used those black ones in several projects.  You have to be very careful about the wire alignment on thinner gauges but they do work. 

(my example is tapping into the white reverse lights on a volkswagen to trigger a relay to turn on a rear view camera... with thin wires and a wide groove, the pointy part in the positap doesn't always want to poke the wire correctly).

[CCCA]

Cool! Your short comment was just enough for me to understand what is going on.   I just realized what a tap is in the website (it's a connection to an existing wire without cutting it).  Just one question though. The link you gave me is for 16-18 gauge wire.  Is that what you think is feeding the fuse box and the 12V outlet, or should I be trying to figure out what gauge wire is there?  I assume if you don't have the right gauge tap, it won't work very well or you might even cut the wire. 

16-18awg is my best guess based on lots of crawling around under car dashes.

Those positaps I linked to are pretty accommodating and would (I think) work with say 14awg too.  No way will the lighter wire be bigger than 14 awg.  worst case you could probably widen the groove/channel that the wire will sit in a little bit to accommodate a larger wire.  You could always go 12-14awg positaps too, but they don't work well if they are "loose" on the wire (the channel the wire drops into centers the wire so that it can be pieced by a screw-in "poking device", so if the wire can wiggle a little bit out of the way, the poker may not poke the wire).

Don't use any other kind of tap under any circumstances than those positaps.  The positaps work very nicely and you will be able to revert to stock if you want to and nobody will be the wiser.  There are other crimp-type taps out there that are far less expensive that absolutely suck to work with and will cause you nothing but heartache. 

haha that's more than I ever thought I'd write about positaps!

Note that there's a Positap part number PT1218B that states it's good for 12-18ga wire. That will surely cover the span that you need to cover.

^^^ True dat.  I've used those black ones in several projects.  You have to be very careful about the wire alignment on thinner gauges but they do work. 

(my example is tapping into the white reverse lights on a volkswagen to trigger a relay to turn on a rear view camera... with thin wires and a wide groove, the pointy part in the positap doesn't always want to poke the wire correctly).

Thanks shawndoggy and sokoloff.  This is extremely helpful.  Looks like I've got a (hopefully) quick project before we go camping this weekend! 

[Just Joe]

Take a look at your fuse panel. You might have a 12V+ terminal just waiting to be used. One of my older cars had that. Already fused too.

All I had to do was crimp on a female spade connector and slip it onto the male spade terminal on the fusebox. Then I ran the wire to the back of the cigarette lighter and crimped on an appropriate connector.

Alternatively run a wire from the 12V+ post of your 12V battery through an inline fuse, through the firewall (stuff the new wire through one of the existing firewall grommets if you can), and to the back of the cigarette lighter. The fuse is important. Without that an overload could cause a fire. You'll need a crimp on loop connector. Two butt connectors for either side of the inline fuse holder, and then whatever kind of connector that the back of the cigarette lighter wants.

Everything in my two solutions is available from a hardware store or auto parts store. I tend to take it "too far" and use shrink tubing to seal the butt connectors and even the end connectors (adds support to the crimp connectors).

[Drifterrider]

Go to autozone (or the like).
Buy a 12V outlet (part # 05349-8) or similar. 
Buy extra wire, alligator clips and electrical tape.

Extend wires, affix clips.

Raise hood, hook to battery, charge.

If you want, make the wires long enough to reach from the battery to the inside of the car so you can keep your item being charged in the car.

[sokoloff]

I would not be comfortable with an unfused wire clipped to a battery hot lead for overnight charging or power usage.

Please put a fuse on the positive (+) lead, close to the battery, at a minimum.

[kwh03001]

If you are camping far enough away from civilization for a dead car battery to be a concern, I would invest in a small secondary battery with a battery isolator.