Auxillary battery - where to fuse?

Always as close to the battery as possible. Your are protecting the wire not the cap.

Thankyou for the reply.....although still a little unclear..fuse on the isolator side or cap. side?

ALWAYS, no matter WHERE the battery is, and in ALL of the input/output wires, and at all of the batteries in a system, fuse within 18 inches of the battery, for the WIRE'S rating!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."

I usually fuse a second battery once under the hood and once in the trunk if thats where its going that way if you are ever in an accident and the power wire somehow gets cut the fuses pop before any electrical fires. lol just my .02

Thanks for the information...Big help!

vinman75 is correct, fuse both ends of the power line.Top Secret, I can tell you but then my wife will kill me.

I might be missing something here but why would you need a second fuse in the trunk? No matter where the wire is shorted or why wouldn't the battery fuse cut all power?

If you have 12v at both ends, with both of those 12 volt sources grounded to the same point (the chassis) if the wire is shorted in the middle, don't you think there should be some way to disconnect BOTH 12 volt sources? If you didn't have a fuse at both ends, the battery in the trunk would remain connected, causing a short-circuit, right? This is why you fuse at both ends.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."

Didn't see in the treads that the second battery was in the trunk. Thought for some reason he was saying you should put two fuses on the same power lead between the battery and amp. You are of course 100% correct if this is the set up.