Cable Size, Amperage for my system
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=88513
Printed Date: May 01, 2024 at 6:13 PM
Topic: Cable Size, Amperage for my system
Posted By: yellowsocks34
Subject: Cable Size, Amperage for my system
Date Posted: January 07, 2007 at 5:52 AM
2002 Yukon 5.3 not sure what size alternator but schucks.com says standard is 105amp. MTX 6500d class d, mono block will be running 2ohm load. 12.5v 2ohm load 500x1, 14.4v 2ohm load 775x1.
MTX 304 (4channel) will be running 4ohm load. 12..5v 4ohm load 37.5x4, 14.4 4ohm load 90x4. (birth sheet says 65x4 at 12.5v) Both amps have 75 total amp fuse ratings (3x25). Now I looked at the Recommended Power and Ground Cable Sizes page here but I didn't feel it answered my questions very well. based on the info there 500/775watts = 80/125amps yet the 6500d will do 500/775watts with only 75amps of fuses.
304 is rated at 150/360watts = 24/~56amps but has 75amps of fuses. Would 4 gauge power be big enough for a 12 foot run? And would my stock alternator be big enough? I have 1 farad cap also. I do like to turn it up loud but not for extended periods at a time. I know the 6500 is class d and more efficient I think its 60 maybe even 70% thought I read that somewhere, while the 302 is maybe only 50%.
Replies:
Posted By: xtremej
Date Posted: January 07, 2007 at 10:18 AM
4 gauge should be sufficent. My only question is the 12' run part, where are you putting the amps/ditribution block? and ditch the cap, they are more for looks than function with what you are trying to accomplish.
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Posted By: yellowsocks34
Date Posted: January 07, 2007 at 3:31 PM
I only esitmated the 12' run. is it going to be longer? amps/blocks more than likely go right behind the back seat in front of the sub box, maybe under the back seat, Or like this: back seat, sub box, then amps on the sub side of the box, which will be facing back of the vehicle. Whats wrong with usig a cap? I know some people like them, some don't. Has there been any evidence that they do more harm than good? Most likely it will only be used on the sub amp.
Posted By: DYohn
Date Posted: January 07, 2007 at 5:29 PM
Caps do more harm than good to your wallet, that is for sure.  If an alternator is being overloaded by a system, the additional load of a cap can exacerbate the problem. If the alternator is capable of handling the load, a cap can help an amp maintain output levels during high SPL transients. For the average user, they are usually a waste of money. ------------- Support the12volt.com
Posted By: yellowsocks34
Date Posted: January 08, 2007 at 4:10 AM
Well guess I will just see after its install what kind of voltage levels I see with and without the cap
Posted By: ricoshay
Date Posted: January 08, 2007 at 12:20 PM
4 gauge should be cool, even if you want to upgrade later. It will probably be around 15' of power wire after concealing it along the length of the vehicle.
Posted By: aznboi3644
Date Posted: January 08, 2007 at 4:08 PM
make sure to upgrade your BIG THREE
Posted By: yellowsocks34
Date Posted: January 09, 2007 at 1:35 AM
No sure if I need to upgrade the alternator one. I think its 8 gauge wire that runs about 12 -18" to a junction box that ties in with the cable running to the starter. From the junction box to the battery is like another 2 feet of 4 gauge wire. Should run 4 gauge straight from the battery to the alternator. That would mean having 4 wires coming from the positive post. (starter, alternator, amps, fuse box under hood) So let me get this straight. There is two wires coming off the negative post. One goes to the chassis and the other goes to the engine. Those are the other 2 wires I need to upgrade? From my understanding there should be one from the engine to the chassis as well?
Posted By: geepherder
Date Posted: January 09, 2007 at 6:57 PM
Yes, upgrade the one from the alternator as well. All the current used by your system/vehicle has to flow through this wiring.
Yes to your other questions as well.
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My ex once told me I have a perfect face for radio.
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