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sizing a main fuse

Printed From: the12volt.com
Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=96122
Printed Date: April 29, 2024 at 4:02 AM


Topic: sizing a main fuse

Posted By: daveward
Subject: sizing a main fuse
Date Posted: August 02, 2007 at 12:55 PM

I recently had a situation in my classic 1982 Mercedes 380sl where I would have benefited from a whole car fuse...meaning a fuse that would pop when the battery to starter wire was grounded! Luckily for me...no damage other than to my wiring and to my belief that I had everything secured properly.

Now I want to install a main fuse between the battery and everything else. My question is how to size it. How many amps would be right? Other than a compressor driven air horn, all the electrical equipment is OEM. Your thoughts would be appreciated. Thanks. Dave



Replies:

Posted By: hotwaterwizard
Date Posted: August 02, 2007 at 8:51 PM

You could use an Amp meter to determine your amp draw.

The problem is when you start the car it draws the most.

I would see how many Amps your Alternator is and use that as a general guide to determine your fuse size.



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John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !




Posted By: hotwaterwizard
Date Posted: August 02, 2007 at 8:58 PM

https://inpcars.com/gxci/

Alternator - 1986-1989 Mercedes Benz 560SL 117.967
by Bosch
Key features
• AL 68 X : 70 AMP
• 1 YEAR WARRANTY

Description
Alternator - 1986-1989 Mercedes Benz 560SL 117.967

I would Install a 75 amp fuse between the Alternator and the car wiring.

 



-------------
John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !





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