: '79 Coupe-Dual alternators?



yomommas
12-14-06, 10:50 AM
Does anyone know of a dual alternator kit for a '79 coupe? Is it even possible to run a dual alternator setup on a '79 coupe deville? If not is there a way to put a bigger (than 63 amps) one on? I just had my alternator replaced, but I'm running a 1500 watt amplifier that has a 150 amp fuse on it. At stop lights and at full volume it starts cutting off. Thanks in advance for your suggestions.

codewize
12-14-06, 11:05 AM
Well one way to combat that is to add additional batteries not included in the field. Only wired for the audio and charged off the alternator.

I'm pretty sure if you go to a parts store and talk about alternators they'll have two available. The standard and what they call heavy duty. The heavy duty around that year was something like 80 amps

If they don't I'm sure someone makes a high output alternator.

Highway Star
12-14-06, 01:02 PM
Check out Quick Start alternators: http://www.alternatorparts.com/

They have a lot of choices in beefed-up alternators and use better than stock components. I've used some of their rebuild kits in the past and have one of their "Iceberg" alts on my pickup (92 Chev). When I get around to it, I'll probably do a slight amperage upgrade on my 79 CDV.

DaveSmed
12-14-06, 01:34 PM
I think you have one of the plain old 10SI series alternators. Got a picture? Anyway.... How big do you want? You can get pretty wild here. But i'm guessing you don't exactly need something like a 350A monster,

I'm guessing something like 94A should do the trick. Go to the parts store and order an alternator for a 1984 High Performance Camaro with the 305G engine.

Benzilla
12-14-06, 03:59 PM
My '79 CDV was ordered with the heavy duty 80 amp "generator" as they call it. It was originally a $59.00 option. You should be happy with one of those, it's the size of a pumpkin lol.

davesdeville
12-14-06, 11:50 PM
I think you have one of the plain old 10SI series alternators. Got a picture? Anyway.... How big do you want? You can get pretty wild here. But i'm guessing you don't exactly need something like a 350A monster,

I'm guessing something like 94A should do the trick. Go to the parts store and order an alternator for a 1984 High Performance Camaro with the 305G engine.

Dave is on the ball. My old 78 had a 10si, and that (84 Camaro) is exactly the alternator it had on it, 94 amps. Should be satisfactory if your 1500w amp is actually 750rms.

The Ape Man
12-15-06, 02:23 PM
Don't forget to replace the wire from the alternator B+ terdminal to the battery plus terdminal with heavier gauge.
I'm using an alternator from a wrecked mid 90s V6 car. IIRC it's rated at 120 amperes. Just changed the pulley, wire and plug to make it work. Ebay is loaded with alternator upgrades for applications like this. A little careful shopping and you will be set. One good alternator might do the trick. Sound system ratings are dubious at best. A legit 1500 watt amplifier would need between 2000 to 2500 watts of electricity to deliver that amount of power to the speakers. They are not 100% efficient hence the heatsink. Maybe borrow a clip on ammeter and get some idea of the actual current needed. Most automotive altenators will turn to toast is asked to deliver more than about 1/3 of their rating for extended periods of time. Some are a little better than others in this regard.
BTW watts are volts (call it 14 volts in this case) times amps. A 200 amp alternator would deliver 2800 watts if installed and working correctly.

N0DIH
12-15-06, 06:07 PM
Why duals? Might want to consider a $100 140amp at Autozone from a 91 Deville 4.9L without heated front glass. Toss on a std pulley and you have more than 2 10SI's ever made factory (best they had were 63amp). The 15SI's were better (same form factor with fiberglass fan) up to 94 amp.

You will be adding a lot of parasitic drag, so you need duals or will a single 140 do it?

Mr_Bam
12-17-06, 09:26 PM
Be careful when you buy "heavy duty" upgraded alternators... I bought 3 before my dumb a$$ figured it out... All for my 425 had 100+ amp output, but all only would put that out above 5,000rpm, hahaha

N0DIH
12-17-06, 09:46 PM
That is why I recommended the 140amp, it is a REAL 140a. It makes tons of power at low rpm.

Remember, to make higher current you need larger windings and they must be closer and closer to the rotor. That is the key to high power.

The 91 Deville and I know the 94 Fleetwood 140amp are easily adapted to older GM brackets that are no the old large frame 80amp. Those are unique, but the old 12SI 70am and the 15SI 85-100 amp are easily upgraded to the 140amp CS144. Avoid the pathetic CS130's, they are failure prone.

Mr_Bam
12-18-06, 07:38 PM
I don't remeber the exact application, but my electric supply guy got me a diesel "generator" that makes 100+ @ idle... Good thing about an engine that doesn't wrap out, I guess haha

The Ape Man
12-19-06, 08:20 AM
I had a 21SI a few years back that would do a continuous 100 amps out without trouble. It wasn't on a Cadillac though. I doubt a single V belt would run that thing for too long.
Another alternator hop up trick is to reconfigure the stator windings into a delta instead of a Y. Peak output goes way up but low RPM current suffers.
No substitute for wire/core size and precision tolerances unless you visit the world of switching supplies.