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I would like to install a quick disconnect jumper cable set on the Ex. I don’t want to clean the snow off to raise the hood to hook up to batteries to jump start, something like wreckers have set up.
My concern. Hitting something hard enough the Ranchhand grill guard can’t protect the front end, shorting the + to ground.
How big a fuse link do I need to crank a 7.3, but blow on a direct short? Conversely, what rating would you need for a DC disconnect switch? How would you switch it without raising the hood?
Man it's going to be a big one. I was just looking at LIttelfuse's datasheet for standard bolt down fuses. (here) Even if you use the 500A fuse, and you're drawing 1000 Amps while jump starting, it'll blow in around 10 seconds depending on the fuse temperature (colder lasts longer). If you use 2 in parallel, that should work for cranking and give you the protection you are looking for should you have a dead short as it should blow in under 1 second. I could look for other (non automotive) fuses but I don't have time to dig at the moment. Maybe that will get you started though.
Thank you for your input, and the link to the little fuse data sheet. Very informative. I do not have a way to measure DC cranking amps but knew it would be crazy high. 1000 amps yikes! Even a disconnect switch will be huge.
Maybe the switch needs to be across the fuse, so the fuse protects against a dead short to ground, but if I am trying to jump start the 7.3 it bypasses the fuse.
Last edited by metalsmith; Dec 6, 2019 at 10:39 AM.
Reason: Grammar
Thank you for your input, and the link to the little fuse data sheet. Very informative. I do not have a way to measure DC cranking amps but knew it would be crazy high. 1000 amps yikes! Even a disconnect switch will be huge.
Maybe the switch needs to be across the fuse, so the fuse protects against a dead short to ground, but if I am trying to jump start the 7.3 it bypasses the fuse.
Yeah you could do that. Another option could be to put the fuse in an easily serviceable location and if you do have to jump it, remove the fuse and bolt down a small bar of copper in its place.