100 amp vs 250 amp fuses

[Black Truck 10 10+ year member]

I know this may be a dumb question but I currently have my amps and wires fused at 100 amp (1/0 gauge going from main battery to AGM then to a distro block into 2 sundown 1000D's and 1 100.4) 3 total fuses needed. At the time I only had 100 amp fuses which is why I put those in.

When I put in my 250 amp fuses does that allow my amps and AGM to receive more power or what? I guess im just confused on what fuses actually do other than break if to much power goes through them. . .

Click to read more...

 

[Pioneer~Saturn 5,000+ posts]

Well, the 250 would have a bit less resistance...but I would just keep the 100's if you aren't having any issues with them...and if you have just one run of 0-gauge running to the rear, I would keep the fusing just like it is, because your 0-gauge run cant handle 750 amps of current and bad stuff will happen before the fuses blow if you short something out...Id keep it how it is

 

[helotaxi 5,000+ posts]

Where'd you come up with 750A? Right now he's fused to 100A. There's a 100A fuse at the battery. That's the bottleneck; all the current has to go through that fuse to get to the distro where the other 2 fuses are. If he's not blowing that fuse, there's no reason to go bigger. If he swaps the battery fuse out for a 250A fuse, it won't change the amount of power going to the amps and the 1/0 wire will still be protected.

There's no difference in resistance between the two fuses. The smaller fuse just melt at a lower temp and that allows it to blow with less current.

 

[jrwalte 10+ year member]

What are you running on those two sundowns? Both of those near full tilt would pop that 100A fuse fairly quickly. You must be drawing less than 2/3rds of what they can output.

 

[helotaxi 5,000+ posts]

It takes more than 100A to blow a 100A fuse. Quick transients aren't usually enough. If he's only listening to music, the crest factor could easily explain the fact that the front fuse hasn't blown. That would be the one I would expect to blow. The others should be fine.