Alternator wiring

Printed From: the12volt.com
Forum Name: General Discussion
Forum Discription: General Mobile Electronics Questions and Answers
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=40953
Printed Date: June 01, 2024 at 11:58 AM

Topic: Alternator wiring

Posted By: wayland1985
Subject: Alternator wiring
Date Posted: October 15, 2004 at 12:52 PM

I'm installing a 200 amp alternator this weekend. They recommended that I reground the car... How do I do that?

Also, they recommended running a ground from the alternator chassis to the negative battery terminal,,, Would that yield two grounds to the negative terminal, or would the alternator ground fix it all up?

Do I need a new wire to my ignition too?

What other things would I need?
Give me the play by play, if you would, so I can get it right the first time...

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~WAYLAND

Replies:

Posted By: Francious70
Date Posted: October 15, 2004 at 2:22 PM

What you'll want to do is go to AutoZone and buy a 4 or 2 AWG negative battery wire (~$5) and drill a hole into the frame of your car. Attach the wire to the frame and to the negative battery terminal. Don't bother with disconnecting the existing chassis ground.

And when they said run w ground from the alternator chassis to the battery, what they were referring to is upgrade the wiring from the alternator to the battery. Should be a red wire.

posted_image

Paul

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Posted By: wayland1985
Date Posted: October 15, 2004 at 10:48 PM

Okay... sounds good.

But here's what I was confused about, under the Notes section of the Installation instructions:
"To ensure a good ground, a flexible stranded copper wire may be used. Attach one end to the rear of the alternator case, and the other end to a clean negative battery terminal."

Is this necessary?

(I will be upgrading the "red" positive wire as well)

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~WAYLAND

Posted By: Mad Scientists
Date Posted: October 16, 2004 at 9:00 PM

I would.. it makes sure that the wiring from the alternator to the battery is good. Why spend the money to buy the alternator and not install it the best way you can?..

regards,

Jim

Posted By: stevdart
Date Posted: October 17, 2004 at 1:14 AM

wayland1985 wrote:

But here's what I was confused about, under the Notes section of the Installation instructions:
"To ensure a good ground, a flexible stranded copper wire may be used. Attach one end to the rear of the alternator case, and the other end to a clean negative battery terminal."

They are referring to the ground that occurs with the alternator attached to the motor with bolts. Often, that is the only grounding there is. You would substantiate the ground by attaching a separate ground wire from the alt body to the battery negative.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

Posted By: the1alchemist
Date Posted: October 17, 2004 at 7:56 PM

i tell people all the time,if you have to ask basic questions like that,at least pay someone to do it the first time,learn from them,then try it yourself on the next one,you are probably talking about a 500$+ part,in a who-knows-how-many thousands of dollars worth of vehicle..
if you screw up,you may LOSE YOUR CAR.. i dont know how i can emphasize that i am NOT saying you are not capable,but learn EVERYTHING you can about the situation BEFORE you experiment..i dont know if you understand exactly what 200 amps is..lets just say this thing (with an iinverter,NOT running it directly(read there is an efficiency issue,even WITH the loss)) it could run an average house,barring an electric stove,or heater..
it could run quite a few lights,a few tv's,sewing machine,and a couple other things at once..
now translate that into a spot that has some high resistance,like a smaller than needed ground,even one that is properly connected,or a loose ground..
that translates into FIRE..or if small enough,or intermittent enough,a small scale explosion(well thats a little extreme,but take a 20 ga wire,and lay it across a battery..that 'poof'didnt even take 25 amps..
hopefully you can find someone like me willing to help you out for a much-smaller-than-normal fee..
i have done this a few times with people and boxes..
first they say 'why $1000.00 for a bandpass box for my jeep???!??!' well,leeme show you.. 80 hours later..
this isnt a safety issue,
but at 60 mph,something happens with the alt and, you and others MAY DIE..wires can be as good as smoke bombs,not allowing you to see..tell him guys(girls)..
enough preaching,i HOPE you get the idea..
GOOD LUCK!! i wish you nothing but the best! I just wish i was there to help!
the way i figure it,this type of install doesn't pay the bills,they are few and far between,the ones that want to learn,get more than what they pay for,literally and figuratively!

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'Stereo' Mike
The Audio CARtist,LLC
9600 Balt. Ave.
College Park,MD 20740
301-474-6260

Posted By: wayland1985
Date Posted: October 17, 2004 at 8:09 PM

Woa, guy, Let's not get too crazy now... I walked into this project with a basic knowledge of electricity. After all, I'm an electrician by trade. Yes, a car is a totally different ball park than a house, but the concepts the same. There are risks in every project everybody asks about in these forums. Mounting an amplifier is just as dangerous as installing an alternator. 200 amps is at a high RPM as well, probably around 5000rpms, or more.

Now I asked this question as a tertiary reference. If you noticed, I have quite a few posts up here, most of them are the same question, rephrased every time. I read two in-depth articles about alternator installation prior to asking this question, which was just for a final reference. I'm not going to pop open the hood, rip the old alternator out, and throw in a new one. I realize some people would.

As for the install, It went well. It took a little while longer than expected, but so far it runs fine. I will need a new belt though (the pulley is smaller).

I thank you for your concern.

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~WAYLAND

Posted By: Mad Scientists
Date Posted: October 18, 2004 at 8:19 PM

"if you screw up,you may LOSE YOUR CAR.. i dont know how i can emphasize that i am NOT saying you are not capable,but learn EVERYTHING you can about the situation BEFORE you experiment..i dont know if you understand exactly what 200 amps is..lets just say this thing (with an iinverter,NOT running it directly(read there is an efficiency issue,even WITH the loss)) it could run an average house,barring an electric stove,or heater.. "

2400 watts isn't all that much... In a house, it would be one 120v 20amp outlet.

Know your stuff of course, but warning of explosions, fires and death isn't really helping get the point across.

Regards,

Jim

Posted By: wayland1985
Date Posted: October 18, 2004 at 9:55 PM

Here's one to create anger amongst the concerned....

The truck was equipped with a 12ga fuse-link before the starter relay. If I were to rewire the system with 2ga, what should I replace the fuselink with?

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~WAYLAND

Posted By: Mad Scientists
Date Posted: October 19, 2004 at 5:04 AM

Fuse link is to protect the wiring..

Rule of thumb is two sizes smaller than the wire being protected; 2ga wire, 6ga fusable link wire.

How did you determine 2ga for 200 amps?..

Regards,

Jim

Posted By: wayland1985
Date Posted: October 19, 2004 at 6:19 PM

That's what the dealer reccomends for 5feet of distance (~3 feet from the alternator to the starter relay, ~2 feet from the starter relay to the battery). Is this not sufficient?

1/0 gauge would be a tight fit, but I could make it happen (using KnuKonceptz power wire)

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~WAYLAND

Posted By: Mad Scientists
Date Posted: October 20, 2004 at 5:43 AM

From this very site..

https://www.the12volt.com/wiring/recwirsz.asp

2 awg is good for 225 amps.. I'm just wondering how often you'll see the full 200 amps output.. 4 awg is good for 150 amps.. I'd be curious to monitor alternator output to see what real output is, not just rated.

How do you plan to terminate the wire?..

Regards,

Jim

Posted By: wayland1985
Date Posted: October 20, 2004 at 9:25 PM

I'm guessing you mean how am I connecting the wires?

I have Gold plated crimp terminals (temporary, now that I'm going to run 2 ga.) Have you any betteer suggestions?

Or if you mean how am I going to ground it, I plan on using the stock ground (to the engine block) and then running a piggyback from the battery terminal to a place on the frame (that I'll grind down)

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~WAYLAND

Posted By: wayland1985
Date Posted: October 20, 2004 at 9:28 PM

BTW, How would you wire a 6 ga. Fuselink? Or is it even necessary???

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~WAYLAND