alt. power wire question
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alt. power wire question im installing an alterstart 180 amp alternator this weekend and plan on doing the battery relocation next weekend. the alt says it needs a 4 gauge power cable and the factory looks to be 8 gauge. will this survive a week or am i going to melt ****?
Joined: Nov 2003
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From: Jacksonville, FL (originally from Toronto Canada)
This question was asked a couple of weeks ago and sparked (pun intended) quite a debate. Basically, if you have a completely stock electrical system then you won't have a problem using the stock wiring but don't wait too long before upgrading.
The alternator only puts out current to meet the demand - it doesn't push power. So a higher amperage alternator is capable of higher current output but it won't do so unless the electrical system needs it. The safety issue involves what happens if you somehow get a dead short in the main cable. The stock alternator doesn't produce enough current to melt the stock main cable even if it shorts - that's why it doesn't need a fuse. However, your replacement alternator is cabable of producing enough current in a dead short situation to melt the cable insulation and possibly start a fire. That's why you shouldn't wait too long to upgrade to a heavier cable.
Also, bear in mind that resistance (and hence heat) increases with the length of a cable. So, if you're doing a battery relocation, you need to use even heavier gauge cable than you would with the battery in the stock location.
The alternator only puts out current to meet the demand - it doesn't push power. So a higher amperage alternator is capable of higher current output but it won't do so unless the electrical system needs it. The safety issue involves what happens if you somehow get a dead short in the main cable. The stock alternator doesn't produce enough current to melt the stock main cable even if it shorts - that's why it doesn't need a fuse. However, your replacement alternator is cabable of producing enough current in a dead short situation to melt the cable insulation and possibly start a fire. That's why you shouldn't wait too long to upgrade to a heavier cable.
Also, bear in mind that resistance (and hence heat) increases with the length of a cable. So, if you're doing a battery relocation, you need to use even heavier gauge cable than you would with the battery in the stock location.
I'm wondering if the alternator would burn out the rectifier diodes or another internal part if it's main power wire shorted. Or maybe it would stop producing output current.
Hmmmmm.
On the other hand, I think the short would be more serious from the battery to the short. The battery just can't turn off and it can produce much more current than any alternator. 800-1000 amps maybe. Now that certainly can burn wire.
As far as upgrading the cable it should help reduce the voltage drop.
Hmmmmm.
On the other hand, I think the short would be more serious from the battery to the short. The battery just can't turn off and it can produce much more current than any alternator. 800-1000 amps maybe. Now that certainly can burn wire.
As far as upgrading the cable it should help reduce the voltage drop.
