Alternator upgrade??? -
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Unread 04-25-2009, 04:56 PM   #1
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1983 CJ7 
Join Date: Jul 2007
Location: Castle Rock, CO
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Alternator upgrade???

It seems like there are upgrades for everything under the sun on our jeeps, but is there an easy swap for an high amperage alternator. I have the 258 and I think that it was a 60 amp alt. Would like to get near a hundred amps or so for an e-locker (or 2), plus lights, heat, radio, signals etc. Any recommendations?

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Unread 04-25-2009, 05:00 PM   #2
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This is the one I have and it works great. It's also a single wire model.
'77 CJ-5 Renegade 304 / T-150, Dana 20, 30/20 axles, Aussie Locker in the Dana 30, American Racing 15x10 Outlaw II's, 33" Dynapro M/T's" ,Optima Battery, TeamRushed + Summit Racing CDI ignition, FlowKooler water pump, Edelbrock Performer Intake Manifold, Holley 4160 390cfm, Herculiner, Silver Ceramic Coated Hedman Hedders, Flowmaster 40's.
Warn PowerPlant HD 12K Winch, Dirtworx front and rear bumpers.
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Unread 04-25-2009, 05:42 PM   #3
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First of all, that's nothing more than a chromed version of a facotry alternator with a 'One Wire' regulator.

Chroming process hardens parts, and the one wire regulator shortens life of the alternator.

First of all, 60 amps is MORE than enough to run everything on your Jeep.

You have to remember, all these 'Super Duper' alternators people are shelling out big money for are just factory alternators people have played with the output numbers...

The 10 SI series can only put out amperage if it can cool the rectifier diodes.
To do this, the diodes are set in aluminum 'Heat Sinks' to carry off and dissipate the heat generated when the current is made.

It's really simple physics,
Without increasing the size (and efficiency) of the heat sinks, the 10 SI series alternators are limited to about 65 to 75 Amps no matter what!

Since the master fusible link to your fuse box/lights is only going to hold back about
50 amps, and anything over about 20 amps above system needs is going to cook the battery, you really don't need a 'Larger' alternator...


Secondly, more RESERVE would be used to power more, as in installing a second battery to take up the slack on the rare occasions your alternator might be overtaxed.

Second batteries are seriously recommended for people that seriously wheel,
Since you can be a LONG way away from a parts store, and two batteries will get you back to civilization or to the trailer/camp where a large 'Super Duper' alternator goes out, and you are JAMMED!
Just BONED with high priced alternator and no reserve to run things!

Third, Consider output of the altenator.
No matter which SI series alternator you use, it's still not going to want to charge at low RPM... Just the nature of the beast.
Even worse if you choose a 'One Wire'...

Consider a CS series alternator as an 'Upgrade'.
They are rated for higher amperage output (Better grade of heat sinks and internal air cooling design) and they put out amperage sooner (down lower) in the RPM range.

The CS 130 series will also bolt right into your brackets,
And with a $25 adapter from NAPA, it will bolt right into your current brackets and plug right into your current wiring.

Since CS 130 alternators were used on all small and midsize GM cars from the late 80's on, there are LOADS of them in the salvage yards,
And they are dirt cheap at the discount parts sores... (no, I didn't misspell 'Store')

Anyway, if you have any questions, feel free to ask...
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Unread 04-26-2009, 11:29 AM   #4
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Is the adapter for the wiring or the brackets, and do you have a part number?
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Unread 04-26-2009, 11:49 AM   #5
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Hammer may be only partially correct in the above post. Yes, the full amperage rating of any alternator will be limited by the amount of cooling available. However, it has been my experience that the higher amperage alternators will produce considerably more amps at low rpm's, where one usually needs it. Most will indeed produce their rated amperage at say 6000 rpm alternator speed, at which point you will need 4 gauge wire and about a 120 amp fusiable link or circut breaker for the alternator battery lead. If you watch the tack and have an amp gauge, you can get away with this for short periods. As for one wire alternators, I have put a large number of them on tractors over the last 12-15 years and have yet to have one fail. Starting diesels puts quite a load on them. All you need to hook up a one wire is the battery lead-no adapter required. You may need to adapt your alternator mounting bracket depending on which of the alternator styles you purchase (and Summit has a pretty big selection).
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Unread 04-26-2009, 02:01 PM   #6
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Might also want to look into the CS144 upgrade... 140 Amps stock. I got one from a u-pull yard for like 20 bucks. The one I found was in an early to mid-'90s cadillac, but I'm sure could be found in more common GM vehicles.
'87 YJ Laredo - 4.0L, AX-15, NP231, 4.10s: 3.5" BDS, 31" Muds

'95 XJ - Donated drive train to the YJ, Parted out the rest

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Unread 04-26-2009, 03:05 PM   #7
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The CS adapter kits are probably for the bracketry and the wiring - the SI uses a variation on a Molex plug, while the CS uses a Delphi Weatherpack variant.

If you want a good job, find a local shop that does alternator/starter rewinds and talk to them. If you can't find one locally; click the link in my sig, scroll to the bottom of the page, and click the San Jose Generator link. I've been using his work for about a dozen years, and Rod's never let me down. You'd be dealing with him directly, and he does keep banker's hours (only problem I have.) He can set up a 12SI putting out 94A for you for around $85 - rock solid and ready to go (the listings that I have on the site for him are for XJ-specific units, but the parts in your 12SI are similar. Hell, the case is probably the same as well - I need to expand those listings, tho.)
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Unread 04-26-2009, 03:25 PM   #8
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Look at late 80's or early 90's chevy/gmc/cadillac vehicles.
Snag a CS130/144 for a few bucks double check the shaft isn't bent
and that it'll spin before you leave the yard. Have it checked at autozone.
Gather the donor vehicles info/spec's for reference later.
Also the CS144 are bigger than a stock jeep alt. but can be mounted up.
PM if you need bracket help
Check out my thread when I had the same questions:
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Last edited by BrockGrimes; 04-26-2009 at 03:39 PM..
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Unread 04-27-2009, 12:53 PM   #9
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1973 CJ5 
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Lots of people with second hand experience...

I had a rebuild shop for about 10 years as a side shoot to my engine machine business, and I actually BUILT/REBUILT the alternators for much of that time.

Some MISCONSEPTIONS are being posted here!

First off, Some FACTS...

Alternators don't start ANY Engines, That's what the batteries and starter are for.

The alternator recharges the batteries and supplies the working load current to the vehicle.

The slower you recharge a battery, the deeper and more complete the charge will be.

The faster you charge a battery, the more heat you will produce.

Recharging at a rate of 30 amps or more for a very long period of time will COOK/KILL most lead/acid batteries.

Blast charging (more than about 20 to 25 amps) will usually start a battery boiling in just a few Minutes...
Heating the plates to the point they boil the electrolyte is BAD for the battery/Batteries.

You vehicle has been running on less than 30 amps to this point....
Somewhere between 30 & 50 amps you would have cooked the Fusible Links that protect both the alternator wiring (and that fusible link handles the ENTIRE ALTERNATOR PRODUCTION, Day in, Day out, year in, YEAR OUT,
If you would have used more than 30 to 50 amps, the fusible link would have blown on either the alternator or fuse block protection circuits.

Outside of the starter motor,
YOU HAVE NEVER USED MORE THAN 30 to 50 amps EVER in the 23+ year history of the vehilce....

Why do you think you suddenly need 150 amps?

They make vehicles that will start in -150F. cold.
They are VERY expensive.
Do you need that expense?

They make vehicles that will traverse the surface of the moon.
They are VERY expensive.
Di you need that expense?

If you have never exceeded a 50 amp load, EVER in the history of the vehicle,
Why do you think you suddenly need an alternator capable of 150 amps or more?


The 'Aftermarket' alternators charge lower in the RPM range because aftermarket suppliers use smaller pulleys on the alternators to turn them faster relative to crankshaft speed.

I've covered this before,
Smaller pulleys are VERY HARD on belts!
The smaller diameter of the pulleys kinks the belt tighter and there for wears out the belts sooner.

Smaller pulleys have less surface area to grip the belt also.
This means problems with turning the 'High Amp' alternators when they are trying to put out at capacity...
(belts slipping and squealing, or sometimes just overheating, cracking, glazing, and failing)

Upgraded 10 SI case size would be a 12 SI alternator, and they have a larger cooling surface area to the Rectifier heat sinks.
They will handle about 85 amps before damage.

It will fit in your current bracket and plug in just like your stock alternator.

12 SI is a viable and cost effective upgrade for a 10 SI alternator,
*IF*... And only *IF*...
You are replacing your current alternator anyway.
The difference between amperages in ranges you don't reach isn't what I'd call 'Cost Effective'...
Since you don't ever draw more than around 30 to 50 amps,
You will never reach the 60+ amp limit of the current alternator,
And it's not an 'Upgrade' if you can't use the extra 20 more amps the 12 SI alternator is capable of...


CS-130 alternator will fit in your current brackets (assuming you get the correct case mounting 'Ears' when you are looking), so there are no bracket changes required.

The adapter is from NAPA and it's about $25 or less, and just plugs into your current plug, and then plugs into the CS series alternators.

The CS series of alternators was designed for 'Electric Everything' vehicles that sit and idle in traffic a lot,
They put out larger amounts of current lower in the RPM range BY DESIGN,
Not by putting on a pulley that ruins your belts!

CS 130 alternators are capable of up to 130 amps if 'Flashed',
but Nominal, constant output is still limited to about 60 to 80 amps.
Plenty for even my CJ which has radios (plural), electric fans, winch, electric air compressor, ect.

Don't let people rush you into something that is expensive, shiny, and you totally don't need...


If you don't need to weld with that alternator, then about 60 amps is all you will EVER need to charge batteries, run vehicle operations/loads, ect.

If you do a lot of low speed operation, and you want more charge lower in the RPM range, consider a CS-130.
It's an easy upgrade, and the CS design makes a lot more current lower in the RPM range...
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Unread 04-27-2009, 01:19 PM   #10
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I ran a truck with dual electric fans. The 63 amp alternator wouldn't keep the fans running and charge the system. Park and need a jump to restart. When I upgraded to the CS130 everything worked out perfect. Low RPM charging while running the fans in city traffic was what my application called for.
This alternator was rated 105 amps bit the low rpm charging is what I needed. I also believe a healthy charging system extends the life of my battery and probably the starter. I have a 94 amp version of the same CS130 for the CJ waitIng for install. Low rpm charging and high output when needed, best of both worlds.
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Unread 02-24-2014, 12:15 PM   #11
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I am going to do the CS130 up grade to my 84 CJ7. my question is which CS130 to use. I need to find one that has the appropriate 105 Amp out put, that uses a V-Belt, and Clocks the correct direction (pulley Fan). I want to buy a new one from my local parts store so any help would be great.

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Unread 02-24-2014, 03:38 PM   #12
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Originally Posted by DirtyCJ7 View Post
I am going to do the CS130 up grade to my 84 CJ7. my question is which CS130 to use. I need to find one that has the appropriate 105 Amp out put, that uses a V-Belt, and Clocks the correct direction (pulley Fan). I want to buy a new one from my local parts store so any help would be great.

Poke around the salvage yards and parts stores when they aren't busy and can look some things up for you...
Try the larger 80's vehicles, they still had V belts and CS alternators.
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Unread 02-25-2014, 05:42 AM   #13
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My notes tell me this should be it.

Napa NAE-66294 105a Delco CS130

And if I documented things well look for these vehicles.

1996-93 Chevy caprice 4.3l 5.7l
1995-92 Chevy lumina apv 3.8l van

Advanced p7922-3 should have V pully from 1990 Buick lasaber estate wagon
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Unread 02-25-2014, 07:07 AM   #14
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Aaron is absolutely correct from my experience. Anything over 60 amps is overkill, assuming your electrical system is in good shape.

My stock 60 amp alternator provides 14.6V to my dual batteries at idle. If I turn on every accessory (headlights, radio, interior lights), the charge drops to the mid/upper-13s at idle, which is still plenty.

You want a trickle charge for long battery life, not a quick charge.

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