should i switch from agu to anl fuse?
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=118564
Printed Date: May 20, 2025 at 12:18 AM
Topic: should i switch from agu to anl fuse?
Posted By: pagaldesi4life
Subject: should i switch from agu to anl fuse?
Date Posted: December 15, 2009 at 7:49 PM
The other day, my inline fuse blew and so I was doing some research on the type of fuse required. I have a Fosgate 1000 watt amp which requires a 100a AGU fuse (running a 4awg wire), however these fuses are hard to find...actually I couldn't find any 100a AGU fuses anymore so I was looking into switching to the ANL type, probably go with a 100a or 150a. My question is, what is the difference between the 2 types of fuses? There shouldn't be any concerns with changing the fuse types right (of course swapping out the fuse holder too) I mean after all both fuses do what they're supposed to..cut power off if anything happens. So, why would an amp require a specific type fuse if they all work the same?
Replies:
Posted By: i am an idiot
Date Posted: December 15, 2009 at 8:04 PM
The problem with an AGU fuse is the blingified fuse holders in which they reside. There is nowhere for the heat to escape from the waterproof fuse holders. A fuse that is not allowed to dissapate heat causes the solder to melt off of the end of the element. This makes a huge troubleshooting issue because the fuse does not look blown. For reliability reasons, you really need to go ahead and upgrade to the ANL fuse. There is a reason they suggest a 100 amp fuse. The fuse is there to protect the amp incase you accidentally touch the speaker wires together. With a 100 amp fuse it will probably blow the fuse. With the 150 amp fuse, the power supply of the amp becomes the new fuse. It is going to cost a lot more than the 5 dollar cost of a fuse to repair that amp. A lot more.
Posted By: KPierson
Date Posted: December 15, 2009 at 8:12 PM
Will an amp actually blow the fuse if you short the speaker leads together? I'm not doubting you, I've just never seen it and didn't think it would blow the fuse. You learn something new every day!
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Kevin Pierson
Posted By: i am an idiot
Date Posted: December 15, 2009 at 8:35 PM
If the volume is turned up, yes it can. And you know that they all work on their system with the amp on and playing. I know that the T3000.1 will blow a 250 amp fuse if this happens. It did not blow the fuse but it did melt it to the point that the amp would play at low volumes. Played fine at low volume. Put the amp on my bench and it worked fine. Sent him back and told him he had to have the volume up when checking the voltage. That is when he found the faulty fuse under the hood. Any properly fused amp should blow the fuse if the speaker wires are shorted together and the volume is turned up. I should have stated any Rockford amp. Most others have protection circuitry that will shut the amp down in this situation. Rockford engineers said protection, what is that?
Posted By: KPierson
Date Posted: December 15, 2009 at 10:27 PM
Yeah, that makes sense - the impedence drops and the power supply tries to pull more current in to supply more current out. I had assumed that is what "protection mode" was for!
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Kevin Pierson
Posted By: pagaldesi4life
Date Posted: December 16, 2009 at 12:14 AM
Interesting, I never knew that. I came across this product tonight: https://www......com/item_2228_Absolute+ICB100.html. I never knew they made one for an automotive application. If I don't go the ANL route, than I might give this a try. If the fuse trips, just reset the breaker....hmmmmm.
Posted By: i am an idiot
Date Posted: December 17, 2009 at 4:12 AM
Save yourself the headache. ANL is the way to go. If that is too bulky, they do now make Mini ANL. You might want to look at that. I know the breaker sounds like the way to go. Not so much.
Posted By: oldspark
Date Posted: December 17, 2009 at 7:51 AM
I'm with you I'mA - AGLs are not good - plus they can suffer from poor quality fuses, end-cap solder, poor end contacts etc (same reason blade fuses crap all over older glass fuses).
The ANLs have no internal joins and should have a positive screw/bolt locking (something I suspect is required for ~40A upwards for normal car fuselinks).
I prefer the look of the ANL's anyhow, but me's a tekhed.
I was looking for resistance specs and found a 100A breaker with a resistance of 75 mOhm - but that means 7.5V at 100A. I wonder if they mean 75uR = 7.5mV? (They refer to ANL fuses as AML!)
But I can't find resistance specs for ANLs, though I did read of one "zero resistance" fuse (and a few funny things over at CarAudio).
And I certainly couldn't find any of my beloved magnetic or hall circuit breakers etc - except typically 3-pole units else ridiculously expensive (ie, several $hundred). Though at $75, maybe 3-pole is suitable for uses as a 3x1, or 1 or 2 or 3 in parallel? (Assuming they break say 24V DC.)
Damn bling audio stuff must have destroyed the old DC-magnetic market!
Posted By: haemphyst
Date Posted: December 17, 2009 at 4:44 PM
oldspark wrote:
But I can't find resistance specs for ANLs, though I did read of one "zero resistance" fuse (and a few funny things over at CarAudio).
Hmmm... A "zero resistance" fuse is a physical impossibility.
1: ALL metals exhibit some resistance: it HAS to or it would NEVER, EVER blow! It couldn't! No resistance equals no heat.
2: The resistance is what makes a fuse function! Pull too much current through said resistance, and the metal heats up to the point of destruction!
Take that little tidbit of ACCURATE information back over to caraudio.com  ------------- It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."
Posted By: oldspark
Date Posted: December 17, 2009 at 5:42 PM
The zero resistance fuse was (probably) not from caraudio - it was just something I recalled spotting. And laughing!
It's one thing I try to get across to people - each fuse is an added resistance (it's heat (= current-squared x R) that fuses them), and their resistance is usually high relative to the cables they are using.
Hence the minimisation of fuses for high power systems - preferably just one at the source (assuming each equipment has its own protection).
It's also why I was searching for magnetic type breakers - they do not require resistance and hence are amoungst the lowest resistance protection available.
Alas it looks like that market has now become a DIY Hall-Effect sensor ($3) with circuit and contactor.
(Who wants to make a fortune $elling the latest "zero-re$i$tance" (& programmable or adjustable) protection that can be remotely controlled & reset? Or will they be as unpopular as someone that blows things like stiffening caps; "complex" (fuel pump) safety cut-out; split charge; and other systems out of the market?)
(Hey Haemo - if you take "zero" resistance literally, we'll call it nano-resistance instead - I think that's trendy enough.)
As to CarAudio, I mentioned one flawed argument/analogy at adding a second battery (page 5) (last para of my brief (LOL) 2009 December 18 at 3:10 AM reply).
Actually I found quite a bit of that CarAudio thread amusing....
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