My Diagram - Determining Wire Gauges

**SKiTLz** · 08-08-2007, 11:16 PM

WTH? I've read numerous times on Car Audio forums you should NOT run your ground back to the battery..

So much BS on the internet

EDIT: http://www.mp3car.com/vbulletin/car-...ng-my-amp.html.. All saying to ground to chassis

**vladcarpc** · 08-09-2007, 05:21 PM

Originally Posted by gokee2

Vladcarpc:
It would help you to help us know what sort of amplifier you are tyring to power because from there, you can easily determine your power wires, ground wires and calculate your fuse ratings in conjunction with your distribution blocks.

HU, AMP and Sub are already installed, I will check its specs and post here.

Originally Posted by gokee2

And yes, I agree with crooper. Dude, there is nothing wrong in trying to wire this yourself. If there is an issue, you can always made adjustments. You can do it, as long as you ask direct questions. We're all here to help

Cheers

Thanks, I think I will try to do it myself...

**vladcarpc** · 08-09-2007, 05:29 PM

Hi! Thanks for your replies.

Based on the drawing of post #4, here are some questions:

1) What awg should I use for power and ground to the lilliput?
2) For the lilliput I think of using a molex connector (HDD) in the PC side and solder the long wire to the Lilliput cigarrete adapter wire that I've cut, so I can use the barrel plug. Or should I solder a barrel plug directly into the new long wire? What do you think?
3) As I posted before, I read that the fuse for the 4 awg wire is 125 amps, can I commit that?
4) About grounding to chassis, is there a recomendation of where to attach it? I mean, can I just fix the wire into any piece of steel below the trunk carpet?
5) Take a look at the other wires' awg that is in the drawing, can I consider them OK?

Thanks a lot, again!

**moleman** · 08-09-2007, 09:46 PM

Everything looks fine, you may want to put a fuse between the distribution block and the carpc just to be on the safe side. Don't want 125 amps shooting into your M2.

I think the lilliput power cable uses 18 gauge wire, so that should be fine. You could go to a thicker wire just to be safe, but I would use the same gauge wire you use for the lilliput on the valet switch so that you don't have to buy extra wire. Unless you just happen to have a bunch laying around.

Whether you solder a new barrel plug onto a new power wire is really up to you. If you are planning on using the screen in more than one vehicle, you may want to make a whole new wire so that you have two. Also if you are using a thicker wire than is used in the stock cable you may want to go ahead and solder on a new barrel plug. Oh and I would recommend putting a fuse on this line too. Screens are expensive to replace.

Oh, and are you powering that USB hub? You may want to go ahead and run a 5v line from the molex you are getting the power for the lilliput from. You don't need it if all you are running is the keyboard, but if you wanted to add more in the future it would make it a lot easier.

Hope that helps.

**crooper** · 08-10-2007, 03:41 AM

Why should you use the absolute maximum fuse? That means you have to hit 125 amps before it'll blow. Putting a 60 on there will give you more protection, not less (it'll blow at a lower amperage). Besides you said yourself in the last table on that link "These are the maximum recommended fuse ratings for the corresponding wire size..." He said in his first post that he's going to use 4 awg power wires, so 60 amps would be under the 125 amp recommended fuse.

**RedGTiVR6** · 08-10-2007, 09:14 AM

The fuse under the hood is to protect the wire as it runs through the vehicle. You're fusing the wire, not the components at this point.

Besides that, if he's determined that he needs to run 4 gauge wire, chances are he's going to be pullng more than 60 amps of current.

The fuse up front shouldn't be grossly under rated for the complete system, nor should it be grossly over rated.

This is why it's critical that we know how big his amp is and what it's fuse rating is.

**vladcarpc** · 08-10-2007, 05:12 PM

My Kenwood HU and AMP are already installed. Bought them in 2002.

Kenwood KDC-X859
- Specs I found in the web:

- 50 watts x 4
- 2 pairs of RCA (4,5V) + 1 pair for subwoofer

- Some pics I found: http://www.ivox.com.br/produto/?dir=...301/6350:64955

Audiobank Power Mosfet KA 4070
- Specs I found in the web:

- 4 x 100 rms 2 ohms
- 4 x 75 rms 4 ohms
- 2 x brigde 180 rms 4 ohms

- Some pics I found: http://produto.mercadolivre.com.br/MLB-61184988-_JM

I hope these specs are enough. If not, tell me and I will search for its manuals. They are already installed in the car, I didnt see the installation, but I can see that there is a fuse in the hood and that's it.

In my diagram I used 4 awg wire just because I read many people using it. Is it overkill in my case? If there is no problem, I would prefer using the thicker wire for safety.

Thanks!!!

**agniusm** · 08-11-2007, 08:00 PM

Hi mate. I think the 4awg wire is the correct one. as i understand you calculate your max draw, total watts. the amps are 200+400watts+160watts(m2-atx)=760watts. then amps=watts/volts=760/13.5=56.29AMPS

From this post: http://www.mp3car.com/vbulletin/car-...-see-here.html
see what lenght you need positive wire and you might get away with 8awg

I would agree with RedGTiVR6 that you would'nt get better ground than wiring strait to the battery's negative.

All amps and PSU has theyr own fuses, so the fuse you are installing is for wire.

**vladcarpc** · 08-11-2007, 08:46 PM

Originally Posted by moleman

Everything looks fine, you may want to put a fuse between the distribution block and the carpc just to be on the safe side. Don't want 125 amps shooting into your M2.

I heard of distribution block with fuses. The M2-ATX comes with a fuse built-in, so you recommend an additional fuse in the wire?

Originally Posted by moleman

I think the lilliput power cable uses 18 gauge (...) Oh and I would recommend putting a fuse on this line too. Screens are expensive to replace.

Good idea. I would need to determine the fuse size for the Lilliput and the M2-ATX.

Originally Posted by moleman

Oh, and are you powering that USB hub? (...) it a lot easier.

I would use it for the keyboard and pen-drive, currently not powered. But I am considering that. Good point.

Originally Posted by moleman

Hope that helps.

Thank you!

**vladcarpc** · 08-11-2007, 08:50 PM

Originally Posted by agniusm

Hi mate. I think the 4awg wire is the correct one. as i understand you calculate your max draw, total watts. the amps are 200+400watts+160watts(m2-atx)=760watts. then amps=watts/volts=760/13.5=56.29AMPS

In the 760watts calculation, what is the 200? 400 is the amplifier.

Originally Posted by agniusm

From this post: http://www.mp3car.com/vbulletin/car-...-see-here.html
see what lenght you need positive wire and you might get away with 8awg

I think that 4 awg is better, just for safety, but I am concerned about voltage drop and wire costs (have no idea).

Originally Posted by agniusm

I would agree with RedGTiVR6 that you would'nt get better ground than wiring strait to the battery's negative.
All amps and PSU has theyr own fuses, so the fuse you are installing is for wire.

I was thinking of buying a distribution block with fuses, so there will be extra protection for each device (Lilliput, M2-ATX).