Battery fuse blows when i hook up new battery

Are you blowing the 80 amp fuse? If yes check to make sure the battery is in the correct way if it's in the right way disconnect the wiring at the alternator, if the fuse still blows the black/red wire is grounded between the junction block and the alternator if the fuse doesn't blow it's the alternator. I hope this helps, Take care.

It's called a direct short to ground. Whatever is on those fuses needs to be checked. Main fuse, is it blowing when you turn on key or when you hook battery? If with switch then trace hot wires from switch. Blown fuses are from overheating, which is what a short does.

Broken or shorted line or relay

You have a 40amp fuse for the key switch, and the main component on the 80amp circuit is the alternator.
I would disconnect the alternator, hook up the battery without the fuse, and use a test light across the 80amp fuse terminals to see if the short has been removed.

damaged wire maybe.
Locate the horn that blows and follow the wire back until you see the damaged area.

Should only be one power wire running to the horn.
Very strange that the fuse/relay didn't stop it from happening.

let me know what you find.

that is the problem . who ever hooked up the fan it is cut into something. I bet if you umhook the fan you will stop blowing fuses

I suggest to check if you have oil leaking onto your alternator or did you recently replace the alternator? Keep in mind that the voltage regulator is built into the alternator on vehicles and I have seen oil leaks internally short the alternator or poor quality aftermarket parts.

Also check ground and wires broke or in short.

sounds like the rectifier is faulty.or a short in the wiring loom check all wires and conectors closley

Power inverters can do this if they are internally shorted or they are being over loaded. If you are just using it to charge a phone or a computer it should not be over loaded. Now if you are charging a computer and running a small cooler at the same time, that may be real close to max which may blow a fuse. Have you tried hooking it straight to the battery to see if it will run what ever you are running. It has it's own fuse so if it has an internal short it will blow that fuse. It if works hooked to the battery and is just blowing the cig lighter or acc. fuse it can be a weak socket. If the socket is hot it may have a loose wire on the back side causing low voltage which can blow a fuse. So hook it to the battery direct, if it works ok there, reconnect it to your acc port and if it is getting hot it may be the weak socket. If it will not run hooked to the battery, it has an internal short and it would be better to buy new than try and fix. Sorry.

its shorted to ground some where