anl fuse

Where did you "add" this fuse? Is it in the power line, between the batteries? Did you put one at BOTH ends of that cable? Is the amp powered off the back battery? Is it between the powering battery and the amplifier? Before you answer, NONE of those questions matter IF the fuse is rated higher than the cable it is installed IN, is not rated for the same or HIGHER current capacity. What size cable is the fuse installed IN? Is it a #4, of so, yes it is too big, as 4 gauge is only rated to 150A. That is even too much fuse for #2, at 225A. (If you have that size fuse in either #4 or #2, you are looking to start a fire... remove it immediately!) You would be safe at 1/0 cable though. More information regarding your supporting installation is needed before we can answer. Read the sticky, there are 3 pages of discussion regarding this.It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

If you have 2 batteries, you MUST fuse at both ends (within 18 inches) of the power cable between the batteries, and in the case of 4 gauge, no higher than 150A. Your system should have three (not GREATER than) 150A fuses in it. BTW, did you read the sticky I linked to? MUCH helpful information there...It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."