Amp power - how to fuse?

[Jack]

I've got two amps to go in the rear of the car, one to power the sub which requires a 30A fuse; and the other to power the components which requires an 80A fuse.

I plan to have one AWG8 cable going from the battery up front, then in the boot using one of they little splitter boxes to supply power to each amp. Question is, how do I fuse it all? Obviously a fuse up by the battery, but what rating? 80A?

Should I also fuse the splitter box too so each amp has its required fuse, one 80A and one 30A?

[Riggy]

when i wired a couple of amps up for my mate , i had a 30A up front near the battery , ran the cable down to the splitter box , and then just used the fuses in the amps for them , didnt bother with extras

although even a 30 up front decided to melt the holder a little when it was on full whack on which point we fitted one of them nice see through round fuse holders insted of the blade style ones

[mikey14sr]

Use 4gauge or bigger between the battery and the boot, 8 is too small and is only just safe for 80A on a 5 foot run, 4 is safe up to 120A. Fuse near the battery should be big enough to handle the maximum draw of all items it's supplying, in your case 110A, so a 120A fuse should do it. 80A just for the component amp sounds a bit big to me though?
Yes use a fused distribution block at the back, with fuses to match what are in the amps. From this point you can use the smaller 8 gauge cable for runs upto a meter long and be safe upto 60A, any more than that I'd continue with the 4 gauge.

[Jack]

Ahh, so up front I need a fuse that rated at the total of both the smaller ones.

Yeah, I did think 80A was a bit much, its only 4x100WRMS. It is an Alpine amp though, and in my experience they do seem to have a habit of asking for big fuses...

Righty ho, cheers chaps :D

[mikey14sr]

If you want to be really sure that te main power cable is up to the job, get some 0 gauge! Look up cables express, they do the cable on it's own and in full kits.

[bump]

Go overboard on your cable. Costs a little extra, but much cheaper than having to replace it at a later date.

Is this going in the nova?

[Jack]

Yes, although I may drop the 30A sub into the Celica for a while to see what its like. Thats assuming I get the car back any time soon.

[Clean 2.0 nova]

With so much current going to the back wouldn't you be needing a second battery to reduce the voltage drop under peak loading. Batteries have internal resistance of say 0.01 ohms, so at 100 amps a battery sitting at 12V will give out a voltage of 11V. Couple this with the resistance of cable and more importantly connections - I think you know where I'm going. I'm no expert on ICE installs but 110A sounds a hell of a lot.

I hope you put as much time into selecting ear defenders!!!

[Jack]

lol it won't be loud, its only a single 10" sub and some components :D

[Stuart]

Id at the very least slap a 1F cap up the back of the car to help smooth things along.

[bump]

hummn, I guess I'll be wiring a split charge system too then lol

[Jack]

As in dual batteries, one up front and one in the back? Hmm, there's a thought lol

That reminds me, do you fancy coming and doing some more welding at some point? :D

[bump]

I'm still up for some welding, got to sort out a mates van first, Think that's starting next weekend, I'll let you know during / after that (Goes for Craig too).

Yep that's the split charge I was thinking, there's no way I can fab up a dual mounting alt bracket that would fit into the free space!

[craig green]

(ock! /\/\

[bump]

(ock! /\/\

:wtf: Was that at me or Jack?