How many amps for my fuse?

[PuZo 10+ year member]

If I'm going to be putting a fuse from the alternator to the battery, how many amps should the fuse be? How do I calculate it? Thanks

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[SplAffair 10+ year member]

fuse at the wires max amp rating

 

[rebelfromva 10+ year member]

If 0/1 300

 

[PuZo 10+ year member]

It'll probably be 4ga, so 60A? Why do I want to do it at the max? Is this to protect the alternator or the battery?

 

[rebelfromva 10+ year member]

250

 

[SplAffair 10+ year member]

why not do 1/0?

 

[Chriszle 10+ year member]

You only need a fuse rated for the output of the alternator, but you can use a larger one if you want.

 

[goingdef 10+ year member]

well if you test continuity along different amp fuses you will find smaller ones choke the flow of current so that 0g wire with all it's capability has now bottle necked at this thin piece of tin with it's high ohm load and low current flow, fuse as large as you can to prevent a fire in case of a wreck or a terminal end falling off your not protecting the alt or the battery your protecting yourself from a possible explosion from a shorted battery on a wire so large it can't burn the lead before blowing the battery, this is why your told to fuse as close to the battery as possible!

 

[quackhead 10+ year member]

I watched a 1995 Ford Mustang burn straight to the ground because the dumb ass did not fuse a 10 ga power wire that shorted under the carpet

 

[SplAffair 10+ year member]

I watched a 1995 Ford Mustang burn straight to the ground because the dumb ass did not fuse a 10 ga power wire that shorted under the carpet

eh it was a mustang. it was well deserved.

 

[smoka 10+ year member]

Get the fuse rating for the wire, then add up the fuses in your amps. If your amps fuse sum is less, go with that value. Always safer to run the smaller fuse size if your system allows.