Max Amp running via Cigarette Lighters

[mslun]

Hi All,

Not sure if this is the right section for the question, please move it to Electronics if its not and apologies in advance.

Anyway...I'm planning to hook up a carpc, amp usage are 8A (laptop power) +1.8A (dc power for usb hub)+ 1.2A (LCD screen) = 11A in total. The lid on the cigarette light suggests that we don't exceed the use of 12v/120W in total for BOTH cigarette lighter outlet (which = 10A maximum on 12v). However I was reading the owner manual, it uses a 20A fuse for the cigarette circuit.

So..here is my question:

1. Is it ok to still go ahead, hook the laptop + usb hub into one outlet (9.8A) and the screen to the other one (1.2A). That would make it 11A in total, I'm pretty sure it wont blow the fuse in the fuse box (since it is 20A) but do you think it will fry the wire? Last thing I want to see is catching a fire.

2. If that really isn't applicable, how hard to wire another outlet through the existing cigarette lighter circuit - from the fuse box, connecting to the existing 20A fuse.

OR

3. Wire a separate one into an empty slot in the fuse box - but it has to be off when the ignition is off. Anyone knows if there is any spare fuse slot which also hook up that way?

LAST question: not related to this problem, but

How do you run the wire through the firewall, I had a quick look in the engine room, but only saw a big rubber cable passing through it. (its for my amplifier)

Thanks very much.

[DJKOR]

That is correct in that the sticker suggests to use no more than 10A in total between the two sockets. In other words, 8A on one, 2A on the other. Standard practice is to put a fuse that is rated for less than the current carrying capability for the wiring.

Now one would think that Toyota put in a 20A fuse meaning that the power sockets can supply at least 10A each. But then again... who knows.

If you have looked at the wiring they have run to each of the socket, I'd be concerned about putting anything more than a sustained 10A load through it. I haven't quite followed the wires and am not sure if there is an independent run to each of the sockets. If there is an independent cable run, then you should be able to run 10A on each socket, but if it merges elsewhere prior to the fuse box, then I'd definitely not put more than 10A combined.

As for running a wire through the firewall, use the grommet that the ECU wiring goes through. You just need to send a coat hanger through there and you'll be set. I wouldn't bother running through the fuse block as this will be really fiddly and not worth the effort. Just connect it to the battery through a fuse and you'd be fine.

This way would probably be a good option because then you can run a 10 gauge length into the car running through a relay triggered by the cigarette lighter power, then into a distribution block. This way you can have up to 35A of devices tied onto it. This is what I have running into my boot (up to 25A at that length), and it's there in case I plan on powering other devices.

[mslun]

This way would probably be a good option because then you can run a 10 gauge length into the car running through a relay triggered by the cigarette lighter power, then into a distribution block. This way you can have up to 35A of devices tied onto it. This is what I have running into my boot (up to 25A at that length), and it's there in case I plan on powering other devices.

Would you please, if u don't mind, explain a bit of how you did that? I don't need to run 35A..not even 25...anything enough for 15A would be more than enough :P

Or to be easier, do you know if there is any spare fuse / fuse slot which also connected to the accessory terminal - so the power is cut when ignition is off?

Thanks heaps again.

[DJKOR]

Looking at all the wiring, it is possible to put up to 20A total through the accessory power socket, but it's one of those things that I'd recommend not to do. I just don't feel comfortable with the idea.

Would you please, if u don't mind, explain a bit of how you did that? I don't need to run 35A..not even 25...anything enough for 15A would be more than enough :P

Or to be easier, do you know if there is any spare fuse / fuse slot which also connected to the accessory terminal - so the power is cut when ignition is off?

I was just saying you can handle up to 35A mainly because that's what the wiring can take. Because the wiring is hidden, 10-12 gauge is really easy to run and provides room for expansion. Plus you can retain your original cigarette lighter socket functionality. If you choose this option, it would wire up something like this:

It saves you from messing with the fuse box and original wiring.

[mslun]

Thanks again.... but it seems a little bit beyond my confidence of doing it....I'm not understanding how to wire it to the accessory terminal..."Red circled" in below image, does it meant to be ignition switch??

Or else......just come up with another idea...

Since I'm not gonna use the power for the factory head unit anyway. Isn't it the easiest way (for my case) would be using its power source? Only thing I'm not sure is how many Amps are running via it?

Recalling ur audio wiring diagram:

Connector 1:

1 - Light Green - Speaker: Front Right Positive (+)

2 - Pink - Speaker: Front Left Positive (+)

3 - Grey - +12v ACC <------------------------------------------ connect to positive terminal of my new cigarette lighter plug

4 - Blue/Yellow - +12v Constant

5 - Blue - Speaker: Front Right Negative (-)

6 - Purple - Speaker: Front Left Negative (-)

7 - Brown - Ground <------------------------------------------ connect to negative terminal (ground) of my new cigarette lighter plug

8 - Orange - Antenna Power (+12v to power antenna amplifier)

10 - Dark Green - Illumination (+12v when tail lights on)

That will do - Providing I'm not gonna exceed the amount of Amps running on the wire ??

Cheers

[DJKOR]

Thanks again.... but it seems a little bit beyond my confidence of doing it....I'm not understanding how to wire it to the accessory terminal..."Red circled" in below image, does it meant to be ignition switch??

Accessory terminal... as in to the two wires that go to the cigarette lighter socket. You can do this at the cigarette lighter end to make it easy. That way power will only run through the relay when the key is in the ACC or ON position.

Since I'm not gonna use the power for the factory head unit anyway. Isn't it the easiest way (for my case) would be using its power source? Only thing I'm not sure is how many Amps are running via it?

Recalling ur audio wiring diagram:

Connector 1:

1 - Light Green - Speaker: Front Right Positive (+)

2 - Pink - Speaker: Front Left Positive (+)

3 - Grey - +12v ACC <------------------------------------------ connect to positive terminal of my new cigarette lighter plug

4 - Blue/Yellow - +12v Constant

5 - Blue - Speaker: Front Right Negative (-)

6 - Purple - Speaker: Front Left Negative (-)

7 - Brown - Ground <------------------------------------------ connect to negative terminal (ground) of my new cigarette lighter plug

8 - Orange - Antenna Power (+12v to power antenna amplifier)

10 - Dark Green - Illumination (+12v when tail lights on)

That will do - Providing I'm not gonna exceed the amount of Amps running on the wire ??

That is correct. You can share some load off there if you want. To be safe, I personally wouldn't exceed 10A, but it should be fine to take 20A. That's just me. I'd also rather have a new length of wiring dedicated to a particular purpose. That way you can still use your cigarette lighter sockets as they were originally intended to be use without having to worry about the extra load that is already tied onto it. If you wanted, you could even run a new length of wire and connect the relay trigger to pins 3 and 7 of the head unit socket.

It's up to you what you want to do.