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08-13-2014, 08:19 AM
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#1
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Mongo the Meet Coordinator
Join Date: May 2008
Posts: 16,899
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Alternator Power Wire Guage
Currently have some 4guage wire from alternator to battery. (Its in the trunk)
Now, since I have AD-freaking-D, I was looking at what size gauge I should have to carry 200amps (max alternator load).
Using this calculator
http://www.powerstream.com/Wire_Size.htm
I should step up to an almost 1/0 size if I want to minimize voltage drop, but I think I would use a 0 gauge. Would go from a calculated drop of 1.25 to .611, which I think would help across the board.
Only downside I see is addition of weight, thoughts? Comments? Concerns?
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Quote:
Originally Posted by KirkEvil
repo bigals turd gen and part it out to a loving home
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08-13-2014, 08:28 AM
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#2
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NJFBOA Co-Founder
Join Date: Jul 2004
Location: All up in your kool aid!
Posts: 12,235
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Going to 1 or 0 gauge will be better and is actually recommended by pretty much everyone and that is what the better relo kits usually come with. You will see less loss, you will see less temp if you get into a heavy cycling situation, and the casing is usually thicker on 0 than 4 so it give the additional safety of resisting chaffing better.
There will be no performance gain, just a better way to achieve the same.
-Tim
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08-13-2014, 09:30 AM
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#3
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Mongo the Meet Coordinator
Join Date: May 2008
Posts: 16,899
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Well, my concern is that assuming a full load of 200amp (which I know, is never gonna happen but that's worst case) the alternator will only put 12.81v at the battery. So, its discharging the battery or at very least, maintaining load only. That is with 4awg.
Now, jumping to 1awg gives me 13.41v at the battery, much better. So its charging and maintaining load.
__________________
Quote:
Originally Posted by KirkEvil
repo bigals turd gen and part it out to a loving home
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08-13-2014, 09:44 AM
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#4
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Stalker
Join Date: Aug 2004
Posts: 12,077
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have you confirmed that much voltage drop at the battery currently? For some reason i can't believe there is that much loss. that would imply the taillights on any car will have a substantial drop as well due to being a thinner wire, therefore more resistance. Yet a voltmeter shows only like .2-.3 volt drop, not 1.5+(edit but thats less current..so nevermind lol). I could be wrong though, but i say just use a volt meter and confirm what you're charging voltage at the rear battery is with the 4 awg. If you do see under 13.2v, then id suggest going to a bigger gauge wire.
Last edited by V; 08-13-2014 at 10:09 AM.
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08-13-2014, 09:48 AM
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#5
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Lord of the rings / 10 Second Club / Meet Coordinator
Join Date: Aug 2004
Location: Millstone Township, NJ
Posts: 6,358
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Go big or go home. Your car needs some weight.
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97 T/A Ram Air Convt
Forever dyno queen / 777rwhp 662 rwtq @ 17lbs / 10.2 @ 140
'24 Corvette Z06
17 Sierra 2500HD Dmax
81 Turbo TA
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08-13-2014, 10:09 AM
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#6
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Mongo the Meet Coordinator
Join Date: May 2008
Posts: 16,899
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Quote:
Originally Posted by V
have you confirmed that much voltage drop at the battery currently? For some reason i can't believe there is that much loss. that would imply the taillights on any car will have a substantial drop as well due to being a thinner wire, therefore more resistance. Yet a voltmeter shows only like .2-.3 volt drop, not 1.5+. I could be wrong though, but i say just use a volt meter and confirm what you're charging voltage at the rear battery is with the 4 awg. If you do see under 13.2v, then id suggest going to a bigger gauge wire.
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Thats just laws of electricity, so with a 200amp load, and that voltage/length/gauge, tis the calculated drop. Taillights don't draw that heavy
Is that all the time? No, but I stand to reason that with all electrical load on, with a hot idle, the 4 gauge is allowing a significant voltage drop. The "feed" for the loads is a 1 gauge so might as well have the battery charge "feed" be the same, at least in my twisted mind.
__________________
Quote:
Originally Posted by KirkEvil
repo bigals turd gen and part it out to a loving home
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08-13-2014, 10:27 AM
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#7
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Stalker
Join Date: Aug 2004
Posts: 12,077
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yea, i actually thought about it then edited my post lol
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08-13-2014, 10:49 AM
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#8
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Mongo the Meet Coordinator
Join Date: May 2008
Posts: 16,899
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Well, so far seems its a good idea, so gonna try this mayhem tmmr.
__________________
Quote:
Originally Posted by KirkEvil
repo bigals turd gen and part it out to a loving home
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08-18-2014, 07:15 PM
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#9
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Mongo the Meet Coordinator
Join Date: May 2008
Posts: 16,899
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So, finally got some numbers from about the system. Also redid the battery positive stud to shut off switch with a new lug and 1/0 wire. There is also a 1/0 jumper from alternator case to a ground on frame.
Cold Idle: 14.30v @ battery, and 12.89v @ fuse panel
Hot Idle: 13.76v @ battery, and 11.80v @ fuse panel
So, looks like I have an issue with the panel feed/ground. It currently feeds off starter lug with a 8 or 4 gauge wire up to it and a short 10 gauge ground. I will call manufacturer tmmr, but my feeling was the ground is just for relays so power flows via each motor ground not all through that panel ground.
Other than that, looks like factory gauge is stupidly inaccurate and I was worrying over nothing
__________________
Quote:
Originally Posted by KirkEvil
repo bigals turd gen and part it out to a loving home
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08-18-2014, 09:52 PM
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#10
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Lord of the rings / 10 Second Club / Meet Coordinator
Join Date: Aug 2004
Location: Millstone Township, NJ
Posts: 6,358
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Not too shabby
__________________
97 T/A Ram Air Convt
Forever dyno queen / 777rwhp 662 rwtq @ 17lbs / 10.2 @ 140
'24 Corvette Z06
17 Sierra 2500HD Dmax
81 Turbo TA
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08-19-2014, 06:19 AM
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#11
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Stalker
Join Date: Aug 2004
Posts: 12,077
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did you check voltage before changing the wires? im curious to see the amount of improvement
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08-19-2014, 06:40 AM
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#12
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Mongo the Meet Coordinator
Join Date: May 2008
Posts: 16,899
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Quote:
Originally Posted by V
did you check voltage before changing the wires? im curious to see the amount of improvement
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Negative, thought about it, but that meant working on a hot ass car so decided not to.
The voltage at the panel with fans on etc worries me, that seems rather low.
__________________
Quote:
Originally Posted by KirkEvil
repo bigals turd gen and part it out to a loving home
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