Power cable..., How thick is yours? Options

[pete]

You've seen the bell-wire under many a bonnet at shows... Well that's not the way to do it, so... On to the power cable needed...

Currently I have a 2awg cabe running down the car, which is already the thickest cable under the bonnet but I've been doing my sums...

OK so I worked out that I'm more than likely going to have 650wrms but that could go up to 800wrms. These figures are the rated powers at 14v but that's the numbers we need...

OK so the EMMA rules say...

(Total Watts X 2) / 13v = Current draw...

So 800 x 2 ( 1600 ) / 13 = 124A.

So I need a cable that the rules give for this current over a 5m length.

0awg it is then!!

I'll post the table later so you can all figure out if your cable is the right one

Pete

[brett]

Pete , i got this link from CAD if you dont know about it . Cabling and fixings at very good prices.

http://www.johndavies.co.uk/newweldingcablesandfittings.htm

0AWG cable something like 10m for £20 or so .

Brett

[pete]

Yes mate my sign in is LeonPete on there...

The problem with using welding cable is it's so much more dificult to run down the car. It generally has less strands and is dificult to bend.

Besides 0awg cable is only about £10 a meter

Pete

[brett]

Cheap like the bird ! ...

brett

[306ICE]

how the hell are you going to run 0awg down your car, its bloody massive!
ive got 4awg which is more than most peoples 8awg shite, and im pulling 830rms maximum! surely im ok though because ive got my Voodoo 1.2f rack cap, right? dont i only have to pull the current from the cap then? about 1 ft to all three amps, so is that all good?
cheers bud, dont want the hassle of changing to 2awg if its not necessary, could split charge but thats money/space in the boot!

[pete]

I've got 2awg already down there, but 0awg will fit easy.

Having the cap in line makes no difference mate. The current is still being drawn from the front of the car, it's just that the Cap helps to give the current quicker as it has a faster responce time. Once the cap has done it's thing, the rest is all coming down the main cable.

How long a cable run do you have down the car? I'll have to look at the tables to see what size it says.

Pete

[306ICE]

the amps are rated 27,28 and the Genesis profile five im not sure (35?) so thats 90amps for say 4.5m(13.5ft). the tables in the haynes ice book. what does your table say?

[pete]

What power output do your amps put out in wrms?

Pete

[306ICE]

240(4x60) and 240(2x120) and 350(4x50+1x150). 830 max rms

[306ICE]

hi guys,
as you can see, it is a shortened version so it would fit in the composing box!
maximum i ever expect to run is 100a current, so i could use 4awg up to 18ft for a 0.5v loss. my cable is 14-15ft, so that fine, 2awg would theoretically serve me up to 200amps, so who would ever need 0awg, im sure your seat doesnt have 2 alternators does it? of is it just to get less than a 0.5v drop.
good luck

CODE

POWER CABLE CALCULATOR
Recommended MINIMUM Gauge Size
Length In Feet For 0.5V Loss    
    Amperage    
Gauge    40    50    60    75    100    150    200
00                                                                            57             38             29
0                                                              61            45             30             23
1                                               60    48    36    24    18
2                               57    48    38    29    19    14
3              57    45    38    30    23    15    11
4              45    36    30    24    18    12    9
5              36    29    24    19    14    10    7
6              28    23    19    15    11    8    X
7              22    18    15    12    9    X    X
8              18    14    12    9    X    X    X

[pete]

I've almost tidied it up for you mate, but you need to replace all the tabs in the text with spaces and it'll look ok then.

By my calcs though mate you'll need 127a worth of cable though not 100a.

Pete

[306ICE]

figure its impossible to draw more current than my alternator output, which is only 90a. or is this completely wrong, as you are drawing current from the battery not straight from the alt.
also my system doesnt drop below 13.9v so thats
(800x2)/13.9 = 115a max.
ill see what the voltage is like with the new capacitor, then decide if i need to up to 2awg or not.

[pete]

Mate you're probably fine but these are guides used in competition.

The calculation is ( WRMS x 2 ) / 13 it doesn't matter what your system voltage is.

You are right about the current being drawn from the battery though if the alternator can not supply the power.

Pete

[pete]

I've used a spare nipple in the factory grommit to get the 0awg cable through. For anyone with a Leon then this pic shows where the cable grommit is. Easy to get to once you've removed the airbox

Notice the cable runs with the standard cables and stright into the trunking. This protects it from getting damaged or caught on any moving parts...

Attached File(s)

 bulkhead.jpg ( 74.78k ) Number of downloads: 94

 

[pete]

Anywhere the power cable needs to pass through or by any metal then it needs protecting from damage. One way of doing this ( the way I have done it ) is to use convoluted tubing taped around the cable where it passes the metal work.

Attached File(s)

 protect.jpg ( 84.59k ) Number of downloads: 44