I have a 2005 chrysler 300 and I am in the process of doing the alternator to batt upgrade. The battery in the 300 is in the trunk so the positive alt wire goes through the fuse box located in the engine bay. Now the power wire for the stereo is fuse in the trunk right next to the battery. My question is for the upgraded wire in the engine bay from the alt postive to the fuse box do i need to add a fuse then connect it to the fuse box or is the fuse that is next to the battery sufficient enough.
Chances are 100% that on a new vehicle like that if the main power fuse of the car blew..the engine would shut down (on much older cars they would still run). This being the case I would say that fuse is unnessecary. Anyone disagree?
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So i take it i wont need a fuse?
As long as the wire you are running from the alternator post to the battery..is fused before it connects to the battery and close to the battery..I see no reason why you would need another. But believe me..if someone disagrees..they will post.
But as I look at it..if a short occurs anywhere along that wire..the fuse of course will blow..since the vehicle will shut down..there will be no output from the alternator...so IMO it is safe without an extra fuse.
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Wait..now I got myself double guessing..sorry. Ok you are running an addtional wire in parallel with the factory wire..Thinking on this situation I would probably want to use another fuse..since tecnically the extra wire is going to allow alot more current flow. Place this fuse as close to the battery as possible and on the battery side of the factory fuse at the panel next to the battery if you connect there.
Sorry for the confusion but your situation is a bit different being a rear mount battery. I had to re think it.
From what I have been told by very competent members here..use this to determine the fuse size..
for a 4ga. wire - fuse at 150A
for a 2ga. wire - fuse at 225A
for a 1/0ga.wire - fuse at 350A
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ok now im confused you said to fust it at the battery butt I already have it fused there due to the stereo. Its a 250 amp fuse. to clear up my configuration heres how its connected batt in trunk positive to fuse wire then runs lenght of car to fuse box in engine compartment then out that fuse box to the alternator postiive. So if im upgrading the wire from the alt to the fuse box your saying there needs to be another fuse before the fuse box?