GM alternator appliction and What amp fusable link - Off-Road Forums & Discussion Groups
Go Back   Off-Road Forums & Discussion Groups > Jeep > Jeep-Short Wheelbase

Jeep-Short Wheelbase All discussion of short wheelbase Jeeps: CJ, TJ, YJ and JK



Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 08-01-2010, 01:44 PM
Sawzall Poster Boy
 
Join Date: Mar 2007
Location: Ft. Wayne, IN
Posts: 626
Thanks: 0
Thanked 1 Time in 1 Post
barrelroll is on a distinguished road
Default GM alternator appliction and What amp fusable link

I read through this team rush post http://forums.off-road.com/jeep-shor...ade-77-cj.html (Best alternator upgrade for a 77 cj) and everything "makes sense" for now except for 2 things.

Do I need to buy a fuesable link or is the 10 gauge wire my fusable link? If I need a fusable link what amp and where do you get it?

Does anyone have an application for a 80-100 amp GM "3 wire" alternator that fits a 304 without too much work? My parts store here isn't the greatest especially if broomhilda is working the counter, she calls our "projects" moropahadites, if just her car at the parts store most of the town keeps driving by...

Oh yeah I guess I have 1 more question in the article it is mentioned to hook up a 14 gauge wire to the horn realy, I don't have a horn relay where else would you go to for an always hot that's "through the harness"? my cj's wiring is in a pile right now so adding a wire or 2 isn't a big deal.
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiFurl this Post!
Reply With Quote
Sponsored Links
Advertisement
 
  #2  
Old 08-02-2010, 05:07 PM
TeamRush's Avatar
Veteran
 
Join Date: Mar 2009
Location: So.West Indiana
Posts: 826
Thanks: 0
Thanked 0 Times in 0 Posts
TeamRush is on a distinguished road
Default

When you connect the large (10 Ga.) wire to the back of the alternator,
You run it up to the starter relay, battery cable side.

There is nothing protecting that wire in the event it gets grounded,
Melted through, rubbed through, ect.
When it grounds, it WILL start a fire!

The Fusible Link is there at the starter relay end of the wire to keep a small issue like a rub through, pinch or getting against the manifold from turning into a full on fire!

As soon as the wire grounds out, the fusible link will burn through sooner, saving your vehicle from a fire.





--------------------------------

The general rule for a fusible link is 4 AWG sizes smaller (2 SAE sizes smaller) than the wire you are protecting.
(AWG = American Wire Gage
SAE = Society of Automotive Engineers)

Example,
10 Ga. wire, 14 Ga. fusible link.
8 Ga. wire, 12 Ga. fusible link.

Fusible links are about $5 each, available from any parts store, and keep you from burning down or blowing up your battery, melting down your wiring harness, so I recommend them.



----------------------------------

Now, some people say you can't have a 'Mega-Amp' alternator with a fusible link...
Which is the usual BS the uninformed pump out.

On average, you alternator will crank out all the power you need without the fusible link ever being an issue.

Since BILLIONS of miles have been hammered on fusible links without people knowing about them, they don't fail very often.

If they were correct (and they aren't) every time you started your engine or ran a winch the starter/winch would draw more current than the fusible link will tolerate, and you would pop a fusible link.

Since they don't know how the system operates, an intact fusible link means your alternator has never produced more than about 30 to 50 amps for very long... EVER!
If it did, the fusible link would blow!

So when most people want to switch to a 'Super Duper' alternator,
I'm usually skeptical...
I'm running a 78 amp that puts out about 70 amps when 'Full Field', (Yes, I have the test equipment) and the fusible links I've installed are still fine several years later,
Even with dual batteries, electric fan, winch, ect.

Your battery (or batteries) and vehicle will NEVER demand more than about 30 amps except when starting,
Which is what the battery is there for, to supply instant current to the high load devices.

The alternator just charges the battery (Batteries) and they take a LOW, SLOW charge or they don't live long!
(the same reason 'Trickle' chargers are good for batteries, while those 200 amp 'Boosters' will kill batteries fairly quickly)

------------------------------

Use the fusible links or fuses to protect your otherwise unprotected wiring to the alternator, and the main feed to your fuse block like the factory used.

Fusible links usually last longer, fuse holders have a tendency to get crud/corrosion in them and stop working, while a fusible link is pretty well sealed (If you install properly with heat shrink) and will live many years without any issues at all.

Fusible links are cheaper, more reliable, available everywhere if you know what to ask for or what you are looking for, and they work GREAT.

'Nuff said?
__________________
So Many Cats, So Few Recipes...

Last edited by TeamRush; 08-02-2010 at 05:11 PM.
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiFurl this Post!
Reply With Quote
  #3  
Old 08-02-2010, 09:11 PM
WILL's Avatar
Official Historian
 
Join Date: Sep 1999
Location: Hot Springs, AR
Posts: 8,295
Thanks: 1
Thanked 2 Times in 2 Posts
WILL is an unknown quantity at this point
Default

Quote:
Originally Posted by barrelroll View Post
Does anyone have an application for a 80-100 amp GM "3 wire" alternator that fits a 304 without too much work?
This is what I have in my CJ. 75-90 JEEP CJ WRANGLER YJ HIGH OUTPUT ALTERNATOR 135 A
__________________
"As the circle of my knowledge grows, so grows the circumference of the unknown." - Isaak Newton
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiFurl this Post!
Reply With Quote
  #4  
Old 08-03-2010, 06:04 AM
CJ7Taz's Avatar
Official Curmudgeon
 
Join Date: Nov 2001
Location: Kansas
Posts: 4,684
Thanks: 1
Thanked 1 Time in 1 Post
CJ7Taz is an unknown quantity at this point
Default

Quote:
Originally Posted by TeamRush View Post
Your battery (or batteries) and vehicle will NEVER demand more than about 30 amps except when starting,
Which is what the battery is there for, to supply instant current to the high load devices.

The alternator just charges the battery (Batteries) and they take a LOW, SLOW charge or they don't live long!
Quote:
Originally Posted by TeamRush View Post
Which is the usual BS the uninformed pump out.
When your engine is running and the alternator is producing, your electrical system draws power from the alternator, up to its limit. The alternator voltage is higher than the battery voltage in order to be able to charge the battery. As long as the alternator voltage is higher, the battery is a load, not a source. If and when there is ever more drain on the electrical system than the alternator can supply, the output voltage falls until it reaches battery voltage. At this point the battery becomes a parallel source supplying what power the alternator isn’t. The battery acts as a surge tank, taking excess power in as charge when it is available, providing reserve power when it is needed.

We are dealing with a Jeep here so we probably don’t have a rear window defroster to deal with. There are still the headlights, running lights, windshield wipers, heater blower fan, etc., some are running electric fans, I have heated seats. The wire from the alternator needs to be sized for the ENTIRE load INCLUDING the charging current of the battery or the maximum output of the alternator, whichever is lower.

The fuse is sized to protect the wire. Now, you could just use a short piece of smaller wire as a fuse. That piece of wire is going to get really hot when it melts, so it must not be able to start a fire if it should. If it should burn through, it leaves two uninsulated ends still connected to electrical sources.

Generally, a fuse link has enough insulation around the small wire such that when it burns through, it does not melt completely through the outer insulation. This prevents the heat from starting fires and provides containment of the two ends so they don’t touch ground.
__________________
There are 10 kinds of people in the world.
Those who understand binary and those who don't.

Last edited by CJ7Taz; 08-03-2010 at 06:06 AM.
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiFurl this Post!
Reply With Quote
  #5  
Old 08-03-2010, 08:29 AM
Jim_Lou's Avatar
Moderator
 
Join Date: Dec 2001
Location: Belleville, Illinois
Posts: 11,300
Thanks: 12
Thanked 14 Times in 9 Posts
Jim_Lou has much to be proud ofJim_Lou has much to be proud ofJim_Lou has much to be proud ofJim_Lou has much to be proud ofJim_Lou has much to be proud ofJim_Lou has much to be proud ofJim_Lou has much to be proud ofJim_Lou has much to be proud ofJim_Lou has much to be proud of
Default

Quote:
Generally, a fuse link has enough insulation around the small wire such that when it burns through, it does not melt completely through the outer insulation. This prevents the heat from starting fires and provides containment of the two ends so they don’t touch ground.
It also makes finding a blown link a little more difficult. Sometimes you can find the burned-through spot by squeezing the link, sometimes you can't.
__________________
EVERYTHING's easy for the guy who doesn't have to do it.
B. Dash Fabrication
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiFurl this Post!
Reply With Quote
  #6  
Old 08-03-2010, 03:02 PM
Caver Dave's Avatar
Mud in my Veins
 
Join Date: Apr 2000
Location: Winston-Salem, NC
Posts: 5,512
Thanks: 0
Thanked 0 Times in 0 Posts
Caver Dave is an unknown quantity at this point
Default

Do yourself a favor, skip the SI-series and go with the CS-series... cleaner power for when you go TBI!

Eagerly awaiting *THAT* how-to article!
__________________
Caver Dave
'72 "Mossy Edition" Commando
the Trail Forge
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiFurl this Post!
Reply With Quote
  #7  
Old 08-03-2010, 07:07 PM
Sawzall Poster Boy
 
Join Date: Mar 2007
Location: Ft. Wayne, IN
Posts: 626
Thanks: 0
Thanked 1 Time in 1 Post
barrelroll is on a distinguished road
Default

Luckly broomhilda was helping some one else and the other parts lady helped me, I have an 85 amp alternator coming for around $85. My parts store only has fusable links down to 14 gauge.

I found this place Catalog and am going to call them up tomorow and order 2 and see how bad shipping is.
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiFurl this Post!
Reply With Quote
  #8  
Old 08-04-2010, 07:52 AM
CJ7Taz's Avatar
Official Curmudgeon
 
Join Date: Nov 2001
Location: Kansas
Posts: 4,684
Thanks: 1
Thanked 1 Time in 1 Post
CJ7Taz is an unknown quantity at this point
Default

What ARE you doing?

Why do you think you want such a high output alternator?

What was wrong with the one you had?

IF you change to the higher output alternator, what wire size are you using for the output?

What does this mean?
Quote:
Originally Posted by barrelroll View Post
My parts store only has fusable links down to 14 gauge.
“Down to” is confusing when talking about wire. The wire size increases as the number decreases.

What is the 14 gauge? Is that a 14GA fuse link for use with 10GA wire or a fuse link for 14GA wire?

You’re gonna need a pretty large wire if you really want 85A output. Chart says 6GA for free air at 60° ambient but depending on where you run the wire, it will probably be at higher than 60° ambient. You will need to go with a larger wire size, maybe 2GA.

You can use multiple smaller wires in parallel BUT EACH ONE MUST BE INDIVIDUALLY PROTECTED. IF that was 14GA fuse links for 10GA wire at your parts store, you could run 3-10GA wires in parallel with each one protected by a fuse link. The smaller wire size is easier to deal with routing exposed or in a loom than the single 2GA. The GM engine I swapped into my Jeep was done this way but I think there were 5 wires, probably 12GA. I’m not sufficiently motivated to go look right now.
__________________
There are 10 kinds of people in the world.
Those who understand binary and those who don't.
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiFurl this Post!
Reply With Quote
  #9  
Old 08-04-2010, 02:58 PM
Sawzall Poster Boy
 
Join Date: Mar 2007
Location: Ft. Wayne, IN
Posts: 626
Thanks: 0
Thanked 1 Time in 1 Post
barrelroll is on a distinguished road
Default

I have 8 gauge wire on the way for the alternator out puts and grounds so I should need a 12 ga fusable link.

Why the big alternator? I'm running a winch and in the near future will have some big lights on the front. I'm not running big lights to be "cool" either but they actually necessary running at night out here, it's real easy to over drive your head lights and sometimes I'm 50 miles from pavement when the sun goes down. I also want the reliability of knowing I have enough juice, I run alone out in the desert a lot, not a place you want your battery to take a dump.
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiFurl this Post!
Reply With Quote
  #10  
Old 08-04-2010, 05:07 PM
CJ7Taz's Avatar
Official Curmudgeon
 
Join Date: Nov 2001
Location: Kansas
Posts: 4,684
Thanks: 1
Thanked 1 Time in 1 Post
CJ7Taz is an unknown quantity at this point
Default

How did you decide on 8GA wire? Sounds small. Chart shows 8GA rated 73A free air, 60°C.

How many lights and what size?

I’ve never had a battery “take a dump”. They go bad gradually and one cell at a time. Overcharging is a good way to kill one though.

I don’t follow your reliability of having enough juice. If you are concerned about reliability, dual batteries with one used as a backup would be my recommendation. 50 miles from paved roads, alone in the desert? Not a good idea but if you must, buy a dirt bike for backup.
__________________
There are 10 kinds of people in the world.
Those who understand binary and those who don't.
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiFurl this Post!
Reply With Quote
Sponsored Links
Advertisement
 
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -5. The time now is 03:41 PM.


Powered by vBulletin® Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Content Relevant URLs by vBSEO 3.2.0
Copyright ©1994-2009, VerticalScope Inc. // Off Road forums & discussion groups sitemap
side by side | atv | dirtbike | snowmobile | sandsport | competition | land use | Jeep | Toyota | Ford | GM