1990 Lexus LS400 amplifier power cable run?

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Death By Bass

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I am looking for some ideas of how/where to run some power cables from the front, to the back of the car...

I'm looking to go UNDER the car, but cant really have a decent look at what I have to deal with, cos all I have it a car jack, and lying on the ground under a car doesn't really give you the big picture :p

the idea is, to run the cables from the engine back, under the car, and then through a hole in the spare tyre well.

has anyone done this? or do people have decent pics of the underside of the car for me to get an idea?

I'm looking to run from the alternator I do believe, not the battery. Its going to be 2 or 4 runs of 0GA cable to a second battery in the back :)

cheers!!!

thanks.
 
4 0 gauges wires ???

do you wish to power up a 10 000watts system?

also, it will be kinda useless, the alternator doesn't push more than 100 amps (1200 watts) so, only 1 0 gauge to charge your battery will be enough.

my twin 4 gauges runs inside the car, i passed them trough the front rail, where the stock wire harness pass trough. not that much a tough job but you need something "fish" the wires. (sorry i don't know how you say what i'm trying to mean in english)

Then, i removed all the floor mat, seats, gas tank, trunk mats etc, insulated the whole car. power wires and remote pass trough the left rocker pannel inside the car, RCA cables passes trough the transmission and drive-shaft tunnel, then under the rear seat then into a rubber plug that i made a hole in it to go into the trunk.

speaker wires passes trough the right rocker pannel then the left speaker passes under the dashboard and about 8-10 inches from the power wires then in the left door.

Grounding is on the driver's rear seat bolt, and 1 on the fuel tank bolt.

Power is connected via a 200AMPS breaker circuit. And i added a few engine and body grounds to the battery.

Passing your wires UNDER the car is kinda crazy, but i think an easy way to do this is to buy electrical galvanised tubing, then pass your wire into them (4 tubes for 4 wires) then you attach the tubes under the car on the floor. also they are easy to bend with a tube bender and will provide full protection to your wires. Not pretty but easy.
 
I was considering two positive and two negative, run directly from the alternator, but I've decided just to use one neg and one pos...

I intend on running the cable through some large garden hose type stuff, and attaching it to the underside of the car...

how much current will the stock alternator actually do? whats it rated for? I couldnt find this info anywhere.

I'm looking at running a 3000watt subwoofer amp, and about 900 watts to the cabin speakers :) lol
 
no need for negative, just ground your stuff on a strong bolt(s) on the body (14mm or more) like i did. Don't use garden hose dude. Go see a qualified electrician near you who works in commercial buildings, he will be able to supply you a nice galvanised steel tubing that you'll be able to pass your wire into. Just paint it in black so it will do a cleaner job. And bend it yo follow your car's floor.

I've got a 1500 watts sub amp and a 700 watts vocal amp and everything works really fine.

As I stated before, the alternator pushes 100 amps (12 volts X 100 amps = 1200 watts) maximum. So you'd better have 2 good 250 amps capacitor so you won't fry your alternator.

if you add a battery in the trunk, simply ground it on the body too. be sure to add a few engine to body or engine to battery grounds, and a few body to battery grounds for your front battery, and you'll be ok.

3000 and 900 is it RMS or PEAK? if it's RMS then I'd use 2 0 gauges positive wires from the front battery to the battery in the trunk. i wouldn't add a better wire between the alternator and the battery, because the better current that can pass trough this wire, the harder the kick will be given to the alternator. the alternator is just there to feed batteries, not supply a sound system, all the current should come from batteries.
 
Nice amp! Impressive power supply. Surprising there’s no cooling fan. There is enough Capacitance in the power supply (Where it should be on the amplifiers rails), so you wouldn’t need the stiffening cap. I have been installing off and on professionally for about 15 years. I would definitely not connect the positive to the alternator, but to the battery with a 200A breaker as close as possible to the battery. The battery is what provides the huge onrushes of current when the bass hits. Upgrade the factory ground wire from the battery to the Chassis. Clean with a sanding wheel the point where you ground everything. Run one 1/0 cable to the amplifiers, and call it good. The size of cable will also help negate the need for a stiffening cap, as that cable’s voltage drop over the length of one car will be minimal. Install a good battery under the hood (Optima starting Red Top, or Marine Blue top if you plan on letting it run down when you are showing off).
 
i was planning on running from the alternator, as the idea was to get a high output alternator, (175amp or so) and run straight from the alternator, to a second rear battery...

by running from the front battery, it means I'll also have to upgrade my alternator to battery wiring, so I can actually get the alternators full 170amps output to the amplifier at the rear... :)
 
You should use a battery isolater like for RV's between your batteries and the alternator. That makes sure you'll only use your aux bettery for the system. As far as where to run it, I ran mine through the passenger side of the firewall just below the spot where the main harness goes through on its way to the ECU. Just pull the oval shaped box just behind your ABS up and out of the way (Charcol canister I think) to get to the firewall there. Pull out your glove box unless you're reall clever, and you're set. Since both ends of your line will be connected to large ammounts of current, put a breaker inline on BOTH ends of the line incase your insulation gets cut on the way through the firewall or under the carpet. Obviously a grommet there is recommended as well. I still would upgrade your ground wire, but in this case from the alternator case to the chassis. The rest of it is fairly easy. Just peel back the carpet, pull out the rear passenger quarter pannel, and off you go. It took me about an hour to run the power wire, connect it, then button it back up. Solder and heat shrink all of your connections for durability. The Big ones are easy with a small propane or MAPP gas torch on a fairly low setting.

As Far as rear batteries go, definately look at an optima marine starting. They are <$100, Deep discharge well, and still have over 750 Cold Cranking Amps. (9000 Watts) of course there will be a voltage drop at that ammount of current.) Your system based on the amp manuf rating will require 4588 Watts to reach full power.
 
passenger side for you = drivers side for me... :p

which would mean I'd be better off running the cable from the alternator, like I first wanted... hmm...

but then... I wonder if the hole you're talking about is therefore on the other side to what you were talking about... lol

who knows!!!

I was going to go attempt to run the cable again today...

wish me luck!!!
 
oh well, I ended up with a hole in the floor, two 0ga cables run through it, and I nearly punctured the fuel line in the process...

oops...

its all good... now, maybe I should have put a gromet thingo around the cable... lol
 
you wasted a lot of money on 0 guage cable to run your negative back to the front of the car, you will probably trip that breaker before you can hear everything the way you want it.... if your power has to travel all the way to the amp/battery and BACK to the alternator, you are putting quite a bit of resistance on that wire. resistance = heat/less total power flow!!! you could save yourself, TIME, MONEY, and the WORK of running that cable if you would ground to the chassis. and a rule of thumb in the car audio industry is the less cable you have going to and from your amp, the better. the more wire you have, the less sound quality you will end up with because you cant flow all the power that you could...

you could also utilize that cable you run as a secondary power cable!!! but you arent pushing near enough wattage to think of needing both cables for 1 amp.

USE A CHASSIS GROUND!!!!!!!!! it just makes sense and cents!!!!

Death By Bass said:
oh well, I ended up with a hole in the floor, two 0ga cables run through it, and I nearly punctured the fuel line in the process...

oops...

its all good... now, maybe I should have put a gromet thingo around the cable... lol
Click to expand...
 
robertk515 said:
you wasted a lot of money on 0 guage cable to run your negative back to the front of the car, you will probably trip that breaker before you can hear everything the way you want it.... if your power has to travel all the way to the amp/battery and BACK to the alternator, you are putting quite a bit of resistance on that wire. resistance = heat/less total power flow!!! you could save yourself, TIME, MONEY, and the WORK of running that cable if you would ground to the chassis. and a rule of thumb in the car audio industry is the less cable you have going to and from your amp, the better. the more wire you have, the less sound quality you will end up with because you cant flow all the power that you could...

you could also utilize that cable you run as a secondary power cable!!! but you arent pushing near enough wattage to think of needing both cables for 1 amp.

USE A CHASSIS GROUND!!!!!!!!! it just makes sense and cents!!!!
Click to expand...

lol, lets think about that for a moment...

hmm... cable from battery to chassis... cable from chassis to amplifier/rear battery... two more cable to terminal connections, two more terminal to chassis connections? 4 more connections = more resistance... plus the possibility of getting a ground loop... terminals cost $7 each... $14 extra for the two extra terminals... cable cost $7.90 a meter... running a cable from the front, to the back, used 3 meters more than if I was to run to the chassis (1 meter front, battery to chassis, 1 meter at the back for chassis to amp) extra 3 meters of cable cost me $23.70... extra terminals would have cost $14... meaning, I spent $9.70 more... saved ALOT of time, and trouble trying to find suitable spots to ground on the chassis AND guarenteed that I wouldn't have any ground loops, PLUS ended up with a less resistive connection...

yeah, I think I'll take my way thanks :madfawk:
 
Ryan said:
Grommet things are good, YOu got the breakers on there right?
Click to expand...

only got the front battery at the moment, and only got a 150amp fuse, but yes, its fused...

going to jack the car up sometime, and put something around the cable where it goes through the floor, plus silicon it up :)
 
Death By Bass said:
lol, lets think about that for a moment...

hmm... cable from battery to chassis... cable from chassis to amplifier/rear battery... two more cable to terminal connections, two more terminal to chassis connections? 4 more connections = more resistance... plus the possibility of getting a ground loop... terminals cost $7 each... $14 extra for the two extra terminals... cable cost $7.90 a meter... running a cable from the front, to the back, used 3 meters more than if I was to run to the chassis (1 meter front, battery to chassis, 1 meter at the back for chassis to amp) extra 3 meters of cable cost me $23.70... extra terminals would have cost $14... meaning, I spent $9.70 more... saved ALOT of time, and trouble trying to find suitable spots to ground on the chassis AND guarenteed that I wouldn't have any ground loops, PLUS ended up with a less resistive connection...

yeah, I think I'll take my way thanks :madfawk:
Click to expand...

damn. terminals are 7 a piece?!?! i can buy mine for 2.50 US to take 0 guage..... **** me in the ***.... good price on cable though..... if you have good terminals chassis grounds use less resistance all together. cable even being GOOD oxygen free will always have more resistance than trying to use a chassis ground system. and if you know what your doing and have good equipment, you will not get a ground loop. and i really dont think you saved any time at all. after doing this in my spare time since i was 15 years old i would know at least this. so im just giving you my 2 cents. because it makes sense. ask a local car stereo shop. they will tell you the same thing.
 
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