ridiculous, can i get a TRUE answer please ? lol

[SLEking]

hey guys. i bought a new 0 gauge wire kit and for the passed three years i've been popping fuses pretty good. so i've been doing extensive EXTENSIVE research on the net and CANNOT come to find one true specific answer about the ONE question i'm looking for. so here it is you guys are smart so i trust you.
I would love to know what size fuse i need to run at my main power (battery to dist. block). first, i heard you add up all fuses in all of your amplifiers together and thats what amp fuse you use for your main. i've also heard COUNTLESS other things lol. so could i just get the simple formula on how to determine this correctly thank you so much
-scott-
btw, happy thanksgiving guys

[00Beast]

Which fuses have you been popping?

[SLEking]

my main power fuse from battery to the distribution block. i know they've all been to small for how power hungry my amps are so thats why i need the correct formula to achieve the correct amp fuse

[crash93ssei]

Even if you had 3 amps and each amp had 2 25 amp fuses, equaling 150 amps total, and you put a 150 amp fuse in your main line, you should never blow that fuse. Fuses on the amps are to protect the amp itself and are the maximum the amp should ever draw. So, if that is the case (not saying your amps use that much power, just an example) and you are still blowing main power fuses, I am thinking maybe the insulation is cut or wore through somewhere along that main power line and it is grounding out. Where is your main power fuse located? That main power fuse is not there to protect the amps, it is there to protect the car from burning to the ground should that wire ground out. Your amps should never blow out the main fuse as long as it is rated for at least the same amount of power combined the amps should draw.

What style fuses are you using? I know the round glass style fuses are quite problematic, and tend to burn out for literally no reason, I have had a few do that on me.

I was told by local shops here to go with either the same amp rating as the fuses on the amp or no more then 20 amps higher then the combined rating.

[SLEking]

im fairly experienced in car audio believe it or not which is why i feel terrible asking such a childish question. my power wires insulation is fine. Also, im running my main fuse around 12 inches from the battery. (12 to 18 is perfect). my one amp has 3X30 watt inline fuses (90 watts) my second amp has 2X25 amp fuses (50 watts) and my third amp has 1X25 amp fuse (25 watts). for the past 3 years i've been using junk round bussman fuses approximately 80 amps tops. being around the block, i know the amperage of the fuse is nowhere near large enough to push these amplifiers. this is why i bought a nice ANL fuse holder and 0 gauge wiring yesterday. i need to know how to calculate the exact amount of amperage my amps are putting out so i know exactly what size ANL fuse i need (ex. 100, 125, 150, 200 etc...)

[its840]

i run a 125 amp breaker up front and a 100 amp fuse in the back.

[1fatcat]

Your combo should never draw more than 165 amps at any time. But realistically, a 150 amp fuse should be more than enough. The fuses on the amplifier are rated higher than the amplifiers actual maximum power consumption. Example: If an amplifier draws 13 amps of power under full load, the fuse will be rated a little higher than 13, like around 20 or 25. This is to provide the amplifier with all the power it will ever need under maximum load, but also provide a fail safe if the amplifier has an internal failure/short circuit and tries to draw more power than it ever should (13 amps in this example). Can you find power consumption specs on your amplifiers?

Remember, if your wire size drops at the distribution block, you are suposed to install a smaller fuse for that circuit. Otherwise, you end up with a 0 guage wire fused @ 150 amps, then drops size to 10 guage but still fused for 150 amps.

[crash93ssei]

im fairly experienced in car audio believe it or not which is why i feel terrible asking such a childish question. my power wires insulation is fine. Also, im running my main fuse around 12 inches from the battery. (12 to 18 is perfect). my one amp has 3X30 watt inline fuses (90 watts) my second amp has 2X25 amp fuses (50 watts) and my third amp has 1X25 amp fuse (25 watts). for the past 3 years i've been using junk round bussman fuses approximately 80 amps tops. being around the block, i know the amperage of the fuse is nowhere near large enough to push these amplifiers. this is why i bought a nice ANL fuse holder and 0 gauge wiring yesterday. i need to know how to calculate the exact amount of amperage my amps are putting out so i know exactly what size ANL fuse i need (ex. 100, 125, 150, 200 etc...)

Fuse distance is good, you want it close to the battery.

So you don't even have the ANL fuse holder and 0 gauge wire installed yet correct? You have only been blowing fuses with your old wire and junk bussman fuses? If this is the case, and you have only been running 80 amp fuses, that is your problem right there. #1 your fuse rating was too small and #2 you nailed it right on the head - junk bussman fuses.

Throw your 0 gauge wire in there with the ANL fuse holder and a 150 amp fuse (unless you can find a 165 or 170) and never worry about it again.

Also, two things here.... fuses are rated in amps, not watts and also your amplifiers don't put out amperage, they draw it (not at all trying to be a smartass here, please don't take it that way)

Your combo should never draw more than 165 amps at any time. But realistically, a 150 amp fuse should be more than enough. The fuses on the amplifier are rated higher than the amplifiers actual maximum power consumption. Example: If an amplifier draws 13 amps of power under full load, the fuse will be rated a little higher than 13, like around 20 or 25. This is to provide the amplifier with all the power it will ever need under maximum load, but also provide a fail safe if the amplifier has an internal failure/short circuit and tries to draw more power than it ever should (13 amps in this example). Can you find power consumption specs on your amplifiers?

Remember, if your wire size drops at the distribution block, you are suposed to install a smaller fuse for that circuit. Otherwise, you end up with a 0 guage wire fused @ 150 amps, then drops size to 10 guage but still fused for 150 amps.

Exactly.

[SLEking]

thank you guys. i will be putting a 150 amp fuse in. I man have missed it (i just got off of work and im tired lol) but i still dont see any specific way how you all calculated what size main fuses you all needed for your systems. I truly appreciate you guys giving me the answer right up front and saving me the headache of doing it myself, but i LOVE to know the math behind the stuff. Btw i have 4 gauge wire running throughout the whole system. ex. battery-->Dist. block-->capacitor-->amps so running a fuse to make up for a smaller gauge after the main power hits the d block was never needed in my case. I'm just waiting for my 0 to come in. the kit comes with an ANL fuseholder + fuse but the fuse is 200 amps>_>. so I have to run 10 miles away to andersons or 10 seconds away to best buy and buy a nice Fosgate anl fuse. also im sorry for putting fuses are rated in watts, believe it or not i knew they were amps so im not even sure why i typed that, hmm. again thanks guys
edit:
after much browsing i may have figured it out.
the formula in ohms law for calculating current draw is I=P/E
I=power:P=voltage:E=current(amps)
what i did was take the MAX power of my 2 kenwoods which totaled 3,600 watts together. Then i cut that in half to get the RMS which is of course 1,800 watts. I then multiplied that by my alternators output of around 14 volts. i came up with about 137.5 amps. Please tell me this is how to calculate this.
Note:i used full 900 RMS from each amp because i run the amps at full power with the head unit at best rated power(75%) 90% of the time i listen to the stereo. So I guess going to a 150 amp fuse should be fine. i would just like to know if this is right lol thanks

[Wes]

You have the math correct. Except, i think you said multiply, when you divided the watts by volts.

You might want to check in the efficiency of your amps though. Some will have an rms of 50%, but some will be at 70% of the max rated power. So that can change your number. If you have the manual, it should tell you the rms value. Or you can likely find it online.

[SLEking]

i believe mine are between 70 and 80 percent thanks wes. and yes i meant divide lol

[1fatcat]

the formula in ohms law for calculating current draw is I=P/E
I=power:P=voltage:E=current(amps)
what i did was take the MAX power of my 2 kenwoods......Then i cut that in half to get the RMS which is of course.....I then multiplied that by.....i came up with about 137.5 amps.

LOL. I just added the amps of your amplifier fuses.

If you have an amplifier with a build in 30 amp fuse, then that is the absolute max that amplifier can draw.

If you want to know what your amplifiers are ACTUALLY drawing, you may want to use an inductive amp clamp and meter. You see, there are so many variables, like, are your amplifiers bridged? Are you using dual voice coil speakers/subs? What ohms are your speakers/subs? What gain level? What input level? What type of box? Ect,,,,

I'm not sure if you understand how this works or not, so let me say it differently. Any amplifier will only consume a certain amount of power under full load. Lets say you have an amplifier that consumes a max of 30 amps under full load. You can feed the amplifier with 100 amps and it will still only cosume 30 at the most. What you want to do is fuse the system for it's maximum wire size capability and RE-FUSE to a lower amp fuse anywhere that the wire size drops. Obviously, your 0 guage wire will handle 200 amps quite easily, as it should max out at 350. However, if anywhere in your system the wire size gets smaller, make sure to re-fuse for the max rating of that wire. Make sure the wire is always big enough for the load its feeding.

The 4 guage wire you are currently using is rated for a max of 150 amps.

Any system needing more than 200 amps should probably be running multiple batteries and possibly alternators? And any system running more than 40 amps needs to be very carefully wired, being very cautious of any metal pass-throughs like firewalls and trunkwalls. Grommets are a must. And under no conditions should any power or ground wire be routed near a hood hinge, door hinge, trunk hinge, brake pedal, be pinched anywhere, or routed too close to screws or sharp objects.

You should be able to run your big fuse at 150 and leave it at that, because your entire system is already rated for 150...assuming your grounds are also 4 guage?

[00Beast]

I agree with fatcat. Your entire system is only as good as its weakest link, and should be wired and fused accordingly.

[spoiledred94]

Check out this link for the right wire sizes and amperes for a 12 volt system. And if my max drawable current is say 100A then I'll go with 20% more (i.e. 120A) a 20% to 30% safety margin is industry standard, I believe.