question on fuses

[3kgt2nv]

when doing a battery relocation with a cut off alot of people put an inline fuse to the alternator. all the write ups and videos show them using a 120-150 amp fuse but the stock alternator fuse is 80 amps. is there a reason people do this or is just overkill

 

[miguelmcv]

people use that with high amp alternators, which they supply more amps, but on a stock alternator you don't need more then what the stock Fuse is.

 

[3kgt2nv]

Ok, thats what I figured. But, just wanted to make sure it wasnt because of extra amp draw due to cranking longer to start the car

 

[miguelmcv]

No, the Fuse is between the alternator and battery, it has nothing to do between the battery and starter, if the fuse would off be in between the battery and starter, then It would apply on what you stated, which will not have the same resistance with the fuse.

 

[3kgt2nv]

Thanks, Was trying to think of every reason people might be using the larger than required fuse in that spot. I understand you want a certain percent above the output of the alternator for the fuse but I have found people using 250 amp fuses inline. That makes no sense to me. At 250 amps the alternator would never trip the fuse.

 

[autodsm]

I always used 2awg wire with a 100amp breaker in line. Never tripped it. Never tripped stock alt fuses anyhow

 

[3kgt2nv]

True, I have never popped an alt fuse either but that is what they are there for is to provide a safe point of failure. Its why I couldnt understand the thinking behind a 250amp fuse. If an alt did over run and start cranking out say 150 amps it would fry all kinds of things and never even get close to popping the fuse