Fuse size vs amplifier output

[LiveAudio911 10+ year member]

Just curious what you guys thought...

Does this sound right, 80 amp fuse for 1200Rms @ 77% efficiency rating?

Additional Detail - Power drop is only by .4~.5% during musical peek

I know you should fuse for the wire & amp.. by getting a big enough wire for the fuse needed... but would it be safe to say if at peak output if your fuse does not blow, would it be safe to say you are fused big enough for the amount of current draw?

I am trying to determine if I really need to fuse bigger or keep it the way it is.. thanks

Click to read more...

 

[iLL Ridge 10+ year member]

I had/have a 60 amp fuse on my rsd 1200. I couldn't get the fuse to go poof.

 

[helotaxi 5,000+ posts]

If it hasn't blown, why would you go bigger?

 

[LiveAudio911 10+ year member]

If it hasn't blown, why would you go bigger?

That was my same thought.. I was up looking at some bigger batteries to possibly replace my stock battery... with an HC2000 and the nub tells me I should put a bigger fuse, a 120a in blah blah blah.. so I just wanted to get some second opinions... make sure I was looking at this the right way..

 

[RAM_Designs 5,000+ posts]

If it hasn't blown, why would you go bigger?

This. No need to change it...you won't be able to blow it without playing tones.

 

[LiveAudio911 10+ year member]

Thanks guys!

I'm going down to get metered for Shits and giggles.. might test that out before I go..

 

[I Like Waffle]

You fuse the wire for the capacity of the wire anyhow, not the draw of the amp. Having too small a fuse is just as bad as having too big a fuse, it needs to be fused correctly for the wire. Ive seen people who run a small fuse that gets really hot but doesnt blow, and it will actually melt the fuseholder and anything around it.

 

[LiveAudio911 10+ year member]

You fuse the wire for the capacity of the wire anyhow, not the draw of the amp. Having too small a fuse is just as bad as having too big a fuse, it needs to be fused correctly for the wire. Ive seen people who run a small fuse that gets really hot but doesnt blow, and it will actually melt the fuseholder and anything around it.

That is very insightful information...

I'm running 4Ga JL power (Blue) wire about 5 ft long,

the fuse holder I have had about 3 years now.. originally holder came with a 140 fuse.. ( I blew that when ever a wire came loose in my box and touched the basket..

During my initial noob triage, I replaced the original wire with the JL wire, ROFL, Sent my amp back and they sent me the amp I have now (score)

Found the wire in the box came loose and touched the mag.. which actually caused the fuse to pop..

I could not find locally a 140 fuse so I just threw an 80 in there.. and forgot about it.. been working ever since..

When I migrated the system to my truck.. I shortened the wire to about 5 ft or so..

I only have a slight drop of power.. mainly at night when lights are on.. just not as bad as my old car being my truck has a bigger battery..

I just wanted to get a bigger bat to hold more power and nub tells me not to change the bat just put a larger fuse in.. hince why I am having this open question..

I'm just gonna post my entire setup for consideration..

Alt- Stock 120 amp ( I think)

Bat- Stock Acid/Lead 850 Cca 1020Ca (rechecked)

Big 3 done-Overboard

1Ga Alt~Fuse

1Ga Fuse~bat

1Ga Block to Frame

1Ga Block to bat

1Ga Bat - to frame

1Ga + Bat to dist. 4Ga JL power running 5 ft ish to amp

4Ga Power wire running to Multi-amp

Ground at amp- 1Ga frame to Dist. block

4Ga From Dist block to amp 1

4 Ga from dist block to amp 2

AMP:JBL 1400.1 wired @ 4 ohm (1200rms)

I mainly just wanted to upgrade the bat to a HC2000 figured it would give me enough storage to make up for what little bit I lack in power. and this came up.. If i do need a bigger fuse I'm going to swap out the dist. block under the hood with ANL fuse holder instead of the blade type I currently have.

Thoughts?

 

[dbjunior 10+ year member]

try running just 1ga from alt to batt no fuse in the middle fuses can actually cause some voltage drop especially when under loads that why some competitors either dont use fuses or they replace the fuse with a solid piece of copper for there runs. this might be what cuasing the dimming of the lights

 

[helotaxi 5,000+ posts]

You fuse the wire for the capacity of the wire anyhow, not the draw of the amp. Having too small a fuse is just as bad as having too big a fuse, it needs to be fused correctly for the wire. Ive seen people who run a small fuse that gets really hot but doesnt blow, and it will actually melt the fuseholder and anything around it.

BS. If it was getting hot is was from a bad connection, not from being "too small."

 

[Wingman0121 10+ year member]

BS. If it was getting hot is was from a bad connection, not from being "too small."

Ya know fuses blow because the solid-core wire in the middle melts from too much power passing through right? Molten copper, hot, link them together?

Usually an amplifier fuse is "slow-blow" rated to cut off at 150% of capacity since you don't want you music to cut out at peak music dynamics, a 60-amp fuse that has 70 amps constantly flowing through it will get hot after awhile, I call it the "premelt" stage.

 

[LiveAudio911 10+ year member]

I've had this 80 amp fuse on for 6 mons.. or so.. maybe up towards a year... checked the connector and no sighs of melting, burns or anything like that.. so I'm gonna assume I'm ok... I think I'm right there... if I drove the amp into clipping or wired for 2 ohm.. (1500 rms) I'd def. blow that fuse or start to melt it at any rate..

I think I'm gonna stick with it.. and upgrade the battery if anything does happen to that fuse I'll swap the fuse holder out for an ANL fuse.

 

[helotaxi 5,000+ posts]

Ya know fuses blow because the solid-core wire in the middle melts from too much power passing through right? Molten copper, hot, link them together?

Usually an amplifier fuse is "slow-blow" rated to cut off at 150% of capacity since you don't want you music to cut out at peak music dynamics, a 60-amp fuse that has 70 amps constantly flowing through it will get hot after awhile, I call it the "premelt" stage.

Actually most fuses are fast blow, but it still take more than 150% of the rating to cause it to "fast blow." They also do not get particularly hot before they blow. The melt temp of the fuse link is quite low. If it weren't it wouldn't provide any safety at all. Its resistance is still very low. If you don't believe me, measure the voltage drop across one with the system cranked. You'd better have a really good multimeter...

 

[Magnus 10+ year member]

Fuses add resistance. //content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif I run no fuses.

 

[helotaxi 5,000+ posts]

Wire and connectors add resistance, too. You shouldn't run wire either...