Auxillary battery - where to fuse?
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=54662
Printed Date: July 06, 2025 at 11:07 AM
Topic: Auxillary battery - where to fuse?
Posted By: gavin9797
Subject: Auxillary battery - where to fuse?
Date Posted: April 26, 2005 at 12:50 PM
I am running a 1 isolator 2 battery system + a capacitor. Any recommendations on in-line fuse or circuit breaker placement? ie: between isolator and battery or between battery and capacitor? Any other suggestions are appreciated.
Replies:
Posted By: tcss
Date Posted: April 26, 2005 at 5:10 PM
Always as close to the battery as possible. Your are protecting the wire not the cap.
Posted By: gavin9797
Date Posted: April 26, 2005 at 9:39 PM
Thankyou for the reply.....although still a little unclear..fuse on the isolator side or cap. side?
Posted By: haemphyst
Date Posted: April 27, 2005 at 12:53 AM
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!
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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."
Posted By: vinman75
Date Posted: April 27, 2005 at 2:42 AM
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
Posted By: gavin9797
Date Posted: April 27, 2005 at 5:23 PM
Thanks for the information...Big help!
Posted By: forbidden
Date Posted: April 27, 2005 at 10:32 PM
vinman75 is correct, fuse both ends of the power line.
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Top Secret, I can tell you but then my wife will kill me.
Posted By: tcss
Date Posted: April 28, 2005 at 5:21 PM
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?
Posted By: haemphyst
Date Posted: April 28, 2005 at 5:50 PM
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.
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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."
Posted By: tcss
Date Posted: April 28, 2005 at 6:30 PM
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.
Posted By: gavin9797
Date Posted: April 28, 2005 at 10:31 PM
LOL...ok now I am getting confused again. I will have one battery for the "car" under the hood. And an Auxillary in the trunk. So are you saying fuse the lead to the car battery or one fuse under the hood for the trunk battery and one fuse in the trunk for the trunk battery? (making 2 fuses for the 2nd battery)
Posted By: haemphyst
Date Posted: April 29, 2005 at 8:26 AM
haemphyst wrote:
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."
Posted By: auex
Date Posted: April 29, 2005 at 9:04 AM
haemphyst wrote:
haemphyst wrote:
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!
haemphyst wrote:
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!
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!
------------- Certified Security Specialist
Always check info with a digital multimeter.
I promise to be good.
Tell Darwin I sent you.
I've been sick lately, sorry I won't be on much.
Posted By: haemphyst
Date Posted: April 29, 2005 at 12:15 PM
What was that, again, auex? Something like this?
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."
Posted By: auex
Date Posted: April 29, 2005 at 2:40 PM
auex] wrote:
haemphyst wrote:
haemphyst wrote:
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!
haemphyst wrote:
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!
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!
------------- Certified Security Specialist
Always check info with a digital multimeter.
I promise to be good.
Tell Darwin I sent you.
I've been sick lately, sorry I won't be on much.
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