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Author Topic: Bigger Alternator for 1990 Chevy Caprice  (Read 3817 times)

Posts: 3


« on: April 18, 2001, 02:04:38 AM »

Hello all,
Has anyone installed a bigger alternator in a 1990 Chevy Caprice. It has a Standard 100 amp. But i am thinking of installing a 500 watt HF amp but need a Bigger Alternator to handel this. A 140 amp or 180 would be nice. I have talked to several alternator shops and they say that 100 - 110 is max out of the current one, because there is no room to rewind it.

Has anyone used a diferent mount to install a bigger alternator?

Posts: 169

« Reply #1 on: April 18, 2001, 10:13:14 AM »

Check with your local Chevy dealer.  There may be a heavier alternator available as part of the Police Package for the Caprice.  If any of your local departments use this car, you might inquire who their local dealer contact is.

73, Larry

« Reply #2 on: April 18, 2001, 09:03:59 PM »


is this amp running on 12 V dc or will it
run on ac ?

Thats a lot of power out from the car,
will your antenna setup let you hear
anyone replying to your output signal ?

in other words, if you can't hear them
then why put out that much power from the car ?

please do not take this as knocking you or you
ideas down, I just want to learn more from you.

73 clay

Posts: 984

« Reply #3 on: April 20, 2001, 06:30:49 PM »

Well, try something different. Maybe you can add a second alternator with a longer belt. I know there was a manufacturer of emergency AC generators in Texas. They mounted on the engine like a DC one and you set the RPMs to 3600 to get 60Hz Ac out of the unit. I see no reason why you couldn't add a second 100Amp alternator and dedicate it to your radio.  Also look at   One of their shows on TNN had a product used on a Ford pickup truck that put out enough DC to be used as an arc welder. You may be able to still buy the video tape of the show.

Posts: 984

« Reply #4 on: April 21, 2001, 11:41:45 PM »

I may have given you the wrong show since the same guys are now on Crank and Chrome on TNN. See their site at:  They have lots of video tapes available and I think one is the one installing the monster alternator in the Ford pickup.

Posts: 65

« Reply #5 on: April 30, 2001, 01:57:28 PM »

Just because the key down demands of the 500 watt amp are over 100 amps does not mean you need a larger battery/alternator supply in your vehicle. The average SSB current would be <40 amps plus (amp) < 8 amps for the transciever or 48 amps total. The battery can easly supply this amount of power. The 90 or 100 amp alternator can supply that current to recharge the battery without a problem.    

Posts: 984

« Reply #6 on: April 30, 2001, 11:32:38 PM »

That answer from WT8Y is partially correct. If you run the battery down from using the radio while not running the engine, he is correct. If you run the radio while driving, especially at night, the vehicle's accessories will demand some of the power along with the radio. As one who has killed a diode in an alternator, I can tell you, get a bigger alternator before you go to high power while driving the vehicle. A twenty amp alternator will recharge the battery as long as nothing else draws power too. You must figure on an alternator the will carry all the load plus the radio and add about 20 percent for surges and protection of the diodes in the alternator. Be safe - get a big one.

Posts: 0

« Reply #7 on: June 19, 2001, 09:56:56 PM »

I have a 95 chevy beretta z26 3.1 v6 it come with 105 amp alternator. I use 4g hot in ground wire 2 1000fg cap. Run a icom 706, amertrom als-500m, Don Johnson Dk3 screwdriver antenna. check it out here @  
In I have a 500watt stereo in the car I use to install car stereo.
You will not be useing all of those amp @ one time.  100 amp is cool.
A good thing to do is chage you car batt for a good car batt with a long reserve time batt. Reserve time = how long dose it take befor the Alternator charge the batt. This will save you on amps time. Look @ some car stereo magzin or go here in look
ask around @ some batt place.  May b this can help you to .
Power Cable CalculatorTotal System Amperage Draw   Up To 4 ft.   Up To 7 ft.   Up To 10 ft.   Up To 13 ft.   Up To 16 ft.   Up To 19 ft.   Up To 22 ft.   Up To 28 ft.
0-20A   14 ga.   12 ga.   12 ga.   10 ga.   10 ga.   8 ga.   8 ga.   8 ga.
20-35A   12 ga.   10 ga.   8 ga.   8 ga.   6 ga.   6 ga.   6 ga.   4 ga.
35-50A   10 ga.   8 ga.   8 ga.   6 ga.   4 ga.   4 ga.   4 ga.   4 ga.
50-65A   8 ga.   8 ga.   6 ga.   4 ga.   4 ga.   4 ga.   4 ga.   2 ga.
65-85A   6 ga.   6 ga.   4 ga.   4 ga.   2 ga.   2 ga.   2 ga.   0 ga.
85-105A   6 ga.   6 ga.   4 ga.   2 ga.   2 ga.   2 ga.   2 ga.   0 ga.
105-125A   4 ga.   4 ga.   4 ga.   2 ga.   0 ga.   0 ga.   0 ga.   0 ga.
125-150A   2 ga.   2 ga.   2 ga.   0 ga.   0 ga.   0 ga.   0 ga.   00 ga.
The above chart shows wire gauges to be used, if no less than .5 volt drop is accepted. If aluminum wire or tinned wire is used, the gauges should be of an even larger size to compensate.Cable gauge size calculation takes into account terminal resistance.

if you would like a better copy send me a e-mail

Posts: 26

« Reply #8 on: September 09, 2001, 11:55:33 PM »

I currently own a 1993 Chevy Caprice Police Package (9C1) .  If I can remember right I think it has either a 120 or 140 AMP alt in it.  The regular caprice had the 105 amp in it.

My previous car was a 1989 Caprice Police Package.

If your totally going to go to a higher alternator, you may look into a Ambulance Supply company.  Alot of Ambulances and Fire Trucks run 200 + amp Motorola alternators.
They might be on the expensive side, so be forewarned.

I am not a mechanic, but also keep in mind that  serpintine belt upgarade may be in need here.  I could also imagine the amount of horsepower the bigger alterntor will rob form the engine. If your not worried about performance, then skip the horsepower thing Smiley

You may want to go the route of a second battery and a RV battery isolator.  I know they sell battery isolators in diff amp ratings, might wanna get one of at least 100 AMP. Also keep in mind cable size...etc to be able to handle the higher charge current to the second battery.
This way you run your amp power to the second battery. The isolater ensures only the second battery is used for the amp, and the main battery used for the vehicle.  There is room under your hood for a second battery, just move the fuel canister behind the headlight.  Or you could run some massive gauge copper cable from the front to the trunk area and mount your battery there...but...the collection of battery fumes may not be a good thing Sad

But now you gotta figure, just about any way you go is going to cost a few bucks.  Why not just run barefoot with 100 Watts Smiley  

Another thing I just thought of, and to watch for.  The Caprice alternators can be prone to noise under high loads.  Back when I was a dispatcher for Frederick City Police Maryland, you could tell which officer was driving a Caprice. When they made traffic stops they would key up and call in the tag, vehicle description...etc, it would put some noticeable whine on the radio. Running a 100 Watt Motorola Micor UHF radio, running the Federal Jetsonic light bar, dash light, halogen flashers...etc, it put a killer load on the alt and would whine.  Only would wine under a huge load, otherwise ok.
Also, something else.
An option on the Police package was a bonding strap kit. GM  bonded the hood, turnk and front and back  bumpers to keep down RFI and have good grounding....just a thought.

Anyways, just a few suggestions
Experiment at your own risk Smiley

Posts: 1

« Reply #9 on: September 11, 2001, 12:01:41 AM »

Is that a Caprice you are driving?  I could not tell what kind of car it was under all those antennas....
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