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Does your amplifier power cable have a fuse AT THE BATTERY?

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I am your Father
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Discussion Starter · #1 ·
Being new here, this is my first poll, so we'll see if I get this right.

I have a question for those of you who have improved your car audio system, by adding amplifiers. (and probably speakers)

Does your main power cable that connects your amplifiers to the battery have a fuse AT THE BATTERY?
 

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i really hope no one votes no. thats damn scarey. is there a rule of thumb as to how big the fuse is supposed to be with certain amplifiers? i am thinking 150A is alittle excessive for a PG tantrum 1200.1 and a 1 farad cap
 

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Discussion Starter · #3 ·
The fuse at the battery is to protect your cable from short circuits, not to protect the amplifier itself, so the rule of thumb would be more dependant upon your cable size, than it would be about the amplifier.

Most amplifiers have their own fuses.
 

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JaredR said:
i really hope no one votes no. thats damn scarey. is there a rule of thumb as to how big the fuse is supposed to be with certain amplifiers? i am thinking 150A is alittle excessive for a PG tantrum 1200.1 and a 1 farad cap
You've never built competition dbdrag cars I take it?
 

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a good rule of thumb is 10amps for every 100 watts rms
i heard that from my friend who runs an Urban Tanks store in dekalb, IL
 

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Or you can add up all the fuse ratings on your amplifiers and use that.

Had I NOT had a fuse on my cable, at the battery, I would no longer have a truck; power cable shifted when I put the carpet and seats back in and got pinched under the seat bracket. It took three months for it to squeeze through the insulation and complete a circuit with the body.
 

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then you tell my friend that, Bill
i think he knows more than you, after all he does work on stereos for a living
 

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Discussion Starter · #11 ·
Does the valet at the restaurant know more about parking than you do? Does the guy behind the counter at McDonalds know more about flavor than you?

The purpose of the fuses at the amplifiers is to protect the amplifiers.

The purpose of the fuse at the battery is to protect your cable & your car from bursting into flames. (As furrycritter learned)

But let's put your friend's theory to the test. Can your friend do math?

For example:
Most amplifiers are less than 50% efficient. Some of the power they consume is converted into musical energy, the rest is turned into heat. (Usually amplifiers are less than 50% efficient, so there's lots of heat)

So if a 100 watt amplifier is 50% efficient, then the power supply of that amp is most likely capable of consuming at least 200 watts.

(Assuming that you have a strong power cable, and your amplifier actually sees 12.5 volts)
200 watts divided by 12.5 volts = 16 amps

But this theory only works for estimating amplifier fusing, not the battery fuse. As I mentioned earlier, the guide for this estimate should be the cable size, and the expected risk/consumption.
 

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Every system is different.
*If you are installing a medium 4 channel amp and it has 2-15 amp fuses then just use a 10 gauge kit and it will more than likely have a 30 amp fuse with it.
*If you are installing a 1/0 cable that supplies a distribution block that feeds 3 amps that have a total fuse rating of 120 amps. Use a 150 blade fuse.
*If you are installing a 100,000 watt SPL monster then you will need to run multiple power cables. It's not required but I don't like to run any single line that needs more than a 150 amp fuse. When you get into the 200 amp fuses you can have a short that is welding steel and the fuse won't always blow. My old truck that had the 24 10's had a battery rack in the bed. I had problems blowing fuses so I made my own aluminum buss bar and put 3-250amp blade fuses together to make a 750amp fuse. I had to remove a amp one day at a competition and was too lazy to pull the fuses out. That was the one time I dropped one of the 2ga cables on the floor "bare metal floor" After a nice loud pop and a bright flash about 3 inches of the power wire was gone and my floor had a 2" hole in it. Guess what....the fuses did'nt blow.
I don't trust breakers. I worked at a shop that sold Phoenix gold products and I have seen many defective breakers. Most of the time you get a breaker that won't reset and it stays open or they trip to easily. I have also seen a couple of them stuck shut. I'm not sure if thats from a heavy surge like a short that might weld the contacts shut but they do go bad.
*Whatever you do don't ever jump a fuse. I remember a customer that bought a Phoenix Gold ZX-350 from the shop. He blew the glass fuse thats under the cover of the amp. He wrapped the fuse in tin foil and put it back in. The amp got so hot "and still played" that it melted into the carpet on the back of the fold down seat. The amp burnt into the seat so bad that we had to use a pry bar to rip it off. And he wanted the shop to pay for his burnt seat :crazy:
 
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