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** Running Positive Wire , Alt to Battery **


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Going to be upgrading all my wiring under the Hood (Big 3 an some) all to 0 gauge. Power wire running from alternator directly to battery.. Should that be fused or no?  I've seen it both ways and would like some feedback on both ways. Not sure to fuse it or not. Currently I don't have positive running directly to the battery,  a positive wire runs to a fuse box/panel then from there the batter. All factory ran (2000 Jeep grand Cherokee). I'm going to be keeping all factory runs just upgrading wire but would also like to add a + run directly from alt to battery just not sure to fuse or not. 

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Doesn't have to be.. But it's best that it is just in case. Say the cable slips off either end and shorts...instant fire. This could occur during an accident or just if it rattles loose over time.. A fuse would save you there in most cases. 

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If you do fuse it, fuse for the amperage of the wire, not the alt. 

If you fuse too low and it pops, boom you're running on battery power with the car on. 

You can run on battery power for a short about of time and then just put in a new fuse. But if it happens and you don't notice it and you're playing your system then you could run into some issues. 

I will say I've never fused any alternator runs ever, as just about 95% of everyone else I know doesn't fuse their alternator runs. 

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I don't fuse between the alt and battery. On my truck the cable is less than 2 feet long. If you really wanted to fuse it then you should fuse it at the alt and at the battery. In the event of an accident, the chances of the battery terminals themselves shorting to ground is high and good quality terminal covers are a must.

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 I have a 2002 Yukon and from the alternator there is a fusible link that is designed to fail if something were to happen to the alternator.  It seems to me that by not fusing the new wire from the alternator to the battery, you would be bypassing that safety feature for your cars electrical system. 

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You have to look at the location of the fusible link to know what it is for. If it is not right at the alternator, then it won't protect the alt wire. As far as the alt is concerned. If it is on the fender well by the battery, then it is protecting the wire from the battery power. 

The second dilemma is: what size fuse would you use? If the fuse is less than alt output, then it will end up blowing at full output. If fuse is higher than alt output, then it won't blow if the wire gets pinched. Alternators don't give full output when hot anyway which adds to the problem.

Put a fuse in if it makes you feel good. 

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I have a tight engine bay and if my alt run chafed to the point of shorting/grounding to the chassis or engine block, I couldnt afford to allow my battery bank to drain.  I fused my alt run as an insurance of sorts.  A 4/0 run with (2) 300A fuses.  Peace of mind - rational or not - was worth the small cost in fuse block and fuses.

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