I have currently a 250 amp fuse on my wire from alt to battery, would upgrading to a 300 amp fuse help or hurt in anyway? Does a bigger fuse give me more amp current to the battery (off a 180 amp alt)?

The fuse is there so that the wire carrying the current does not heat up and melt/cause a fire... So going higher would allow a higher current without going into protect, but if you're using a 180a alternator then I don't think it would make a difference so I would keep it how you have it..

i was always told to fuse to the wire, could be wrong but if your cable can handle 250a then fuse with 250a.

What size wire? I assume 0 gauge? Then 250-300 amp anl fuse should be more than enough.

Yes, o gauge wire. If i would upgrade to a DC 270xp amp alt then i should up the fuse to a 300 amp?

I would fuse to the amps or watts you plan on using unless it will exceed the wire.

here is a good calculator to see what you need. go down to single phase and enter in watts and volts and it will give you what amps that will pull.

http://www.jobsite-generators.com/power_calculators.html

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I would fuse to the amps or watts you plan on using unless it will exceed the wire.

here is a good calculator to see what you need. go down to single phase and enter in watts and volts and it will give you what amps that will pull.

http://www.jobsite-generators.com/power_calculators.html

Thanks for the link... If it is accurate then its pretty good....

The fuse rating you use is based on wire size and length. The chart within the link posed above is accurate for 12v use.

The fuse rating you use is based on wire size and length. The chart within the link posed above is accurate for 12v use.

The fuse rating that you use is based on wire size only. The wire size you choose is based on current requirements and length. Length is irrelevant when considering fusing. A wire's max capacity for fuse purposes is based on the amount of heat that the wire will generate and can dissipate per unit length. This is a constant regardless of length. The usable amp capacity of a wire is based on size and length. This is determined by the amount of voltage drop across its length. The voltage drop is based on the resistance per unit length. If either the length increases or the current increases, the wire size must increase to keep the voltage on the other end at a usable level.