65 Amp Alternator

[Ooooner]

I have replaced my "stock" alternator on my 73 GT with a 65 Amp alternator from OGTS. I was reading an article the other day that caught my attention. It said that by increasing the Amps from the alternator, I should replace the stock wiring or install relays at critical points in the wiring harness.
I talked to Jarrell (Soybean) today and he said that is what he did. I was just wanting to see if any of you had problems by going to a higher amperage alternator and not changing the wiring or adding relays. If you think it is important to upgrade the stock wiring, which is in very good shape, where would you start? My headlight wiring has already been replaced so the wires there are OK. Thanks, for any advice....

[RallyBob]

Originally Posted by Ooooner I have replaced my "stock" alternator on my 73 GT with a 65 Amp alternator from OGTS. I was reading an article the other day that caught my attention. It said that by increasing the Amps from the alternator, I should replace the stock wiring or install relays at critical points in the wiring harness. I talked to Jarrell (Soybean) today and he said that is what he did. I was just wanting to see if any of you had problems by going to a higher amperage alternator and not changing the wiring or adding relays. If you think it is important to upgrade the stock wiring, which is in very good shape, where would you start? My headlight wiring has already been replaced so the wires there are OK. Thanks, for any advice....

It depends. If you never actually intend to utilize the 65 amps, then you're fine. But if you're gonna be drawing 50 amps or more, I'd seriously consider replacing all the fusible links and/or installing inline fuses (a good idea anyway), increasing the main alternator feed wire size (8 ga or so), and doing the same for the wiring to the ammeter. Otherwise you'll find the weakest link sooner or later.

[Dmcbrass]

It's really important to follow the Opel scheme when adding additional electrical load. All electrical load should originate from the alternator side of the fuse box. This keeps the current feeding these loads from going through the ammeter. (the exception to this would be when using these devices when the car is not running) This way only the current needed to replenish a drained battery will normally go through the ammeter.

[hrcollinsjr]

Originally Posted by RallyBob seriously consider replacing all the fusible links and/or installing inline fuses (a good idea anyway),

I installed a circuit breaker years ago in place of an inline fuse. If you use an inline fuse make sure it is rated a little higher than the output of the alternator. If you install one rated the same as your alternator output then at full charge it can melt the solder in the fuse. Then when you try to replace the "blown" fuse the solder is in the spring of the fuse holder.

Harold

[Ooooner]

Right at the moment, I do not plan to add anything else to the stock things that are on the GT. I do plan to add an electric fan in the future. I just basically wanted to get the lights on the dash and headlights running brighter and the 65 Amp alternator sure did that! But at the same time, that means more juice is running through the system so I was just concerned about that....
Thanks for the input...

[RallyBob]

Originally Posted by Ooooner Right I just basically wanted to get the lights on the dash and headlights running brighter and the 65 Amp alternator sure did that! But at the same time, that means more juice is running through the system so I was just concerned about that.... Thanks for the input...

Actually that's just the GM voltage regulator doing its' job better than the Opel regulator. Higher voltage = brighter lights. You'll actually have less of an amperage draw this way! I've seen this in all the cars I've swapped over to GM alternators as well. They tend to run at 13.8-14.2 volts for the most part. The Bosch stuff tends to be almost a full volt lower.

[Ooooner]

Bob,
Now that you mention it, I remember that higher volts mean lower amps or the other way around. I guess I can remember the electrical course took in college. It is coming back to me!

[namba209]

There you go Roy, just remember the high voltage transmission lines that run electrical power from source to the cities. They are normally 125,000 Volts, but 1/4 amp. They get changed back at the transformer switching stations to 120 Volts and bunches of amps.

[Dmcbrass]

It's too bad that someone doesn't come out with a voltage regulator with a higher target voltage. The original alternator has all of the current potential that most GT owners need, just not enough voltage. A voltage regulator is a pretty simple device. I've got to believe that at least one of our members is innovative enough with the electrons to get the job done.

[kwilford]

Originally Posted by Dmcbrass It's too bad that someone doesn't come out with a voltage regulator with a higher target voltage. The original alternator has all of the current potential that most GT owners need, just not enough voltage. A voltage regulator is a pretty simple device. I've got to believe that at least one of our members is innovative enough with the electrons to get the job done.

In fact, an electronic voltage regulator that is a matched fit for the Opel Bosch regulator is available with an ADJUSTABLE voltage output. It has a small "pot" (potentiometer) cast into it that allows the voltage to be adjusted by turning a screw. I believe it allows about three or four volts +/- of adjustment in total, although I still haven't tried it (no working Opel blah blah blah...).

I bought mine from a guy on eBay (Dave Barton, aka "dbarton" http://feedback.ebay.ca/ws/eBayISAPI...userid=dbarton ) who occasionally sells Volvo parts. I believe Volvo's from the late '70's used the same alternator as the Opel. He sold two styles of adjustable regulator. One replaced the built-in version (attached to the removable brush pack) on the later model ('75) 55 amp Opel OEM alternator, and another (that I bought) that used the standard pig tail connectors (which, IIRC, was used on the turbo Volvo's to avoid the heat related to the turbo piping).

You might try contacting Dave to see if he can tell you where to get them.

HTH

[duaneb]

If your lights are brighter after replacing the alt. it means your voltage has gone up. And also your amps. Amperage in any given circuit is determined by two things , the voltage and the resistance of the circuit. If you feed higher voltage to a light it will burn brighter . The only wires you need to worry about increasing the size of is the main wiring from alt to fuse box and this only because with the larger alt you have a larger current POTENTIAL. If you dont add any load (big amp for your stereo etc )all your origional wiring will be fine.

This is all determined by Ohms Law.

E=voltage
I=amperage
R=resistance

E=IxR
I=E/R
R=E/I

It all sounds complacated but it really isnt. The wiring in your Opel was designed to handle all the stock electrical components on your car. The higher amperage alternater will charge a low battery faster and allow you to add accessories without overloading the alt.
Hope this helps and dosent confuse you as much as it did me when I first studied it many years ago.

[opelgtmaster3]

i didnt change anythingwhen i put the 65 amp alternator in. i have a really powerfull stereo in that gt and i have no problem with wires heating up. iv had the alternator in the gt for about 2 years now and everything seems to be fine

[markandson]

Keep in mind that a poor connection at a spade terminal or anywhere else for that matter, will increase resistance and with more voltage available will draw more amps, which in turn creates HEAT! So in order to protect what you have, your car, you should make sure that all the connections in the car, especially those using alot of power, are clean.

[Dmcbrass]

There's a lot of good information being shared in this thread; however, we need to keep things in perspective. While its true that with a given resistance, current will increase as the voltage increases, that increase is relatively low. If the Voltage increases from 13 to 14 volts that's less than a 8% increase. A 5 amp current flow would increase to 5.4 amps. Not earth shattering. Also remember that some power users such as stereos, represent variable resistance. A given sound level requires a certain number of watts. 100 watts is still 100 watts. Since DC power equals the Voltage multiplied by the Current, (P=V*I), As the Voltage increases the Current actually decreases for a given amount of power. This is what Rally Bob was referring to. Unfortunately headlights don't follow this rule since they represent a fixed resistance. Even in that case though, the current flow to headlights is less than 15 amps, so the increase in current flow would only be 1 amp. Not worth writing home about.

[Ooooner]

Great information. You guys are making remember the things I learned in college a long time ago. Maybe my brain isn't half dead after all! Seriously though, I will definitely check on some of the things that some of you have suggested. The GT I have has been garaged just about it's whole life so the original wiring is in great shape. You can't be too careful with the wiring in our GT's!