cool 2 wire alternator.

C

clutchdust

Millionaire Playboy
Joined
Mar 27, 2008
Messages
1,728
Location
In transition
i can't quite explain it but i have one of the conventional 3 wire alternators on my car. well, since my wiring is kind of hacked up right now, i just ran a wire off my charging stud to the #1 terminal to excite the regulator. but i was told i need to put a resistor in the line going to the regulator to keep the regulator from causing a drain when the car is not running. so i soldered a resistor into that wire and everything seemed to be fine. then one day i noticed the solder had broken/melted apart. this seemed odd since the alternator has been working correctly for who knows how long. so for the last 3 or 4 months i've been running the car with the charging line and a single 12v wire going into the #2 terminal of the regulator with no problems. i notice that when i first start the car i don't show a charge but as soon as i bring the RPMs up to 1000-1100, the alt self-excites. interesting, but it works. i'll straighten it out once i'm actually done with the rest of the engine compartment.
for now, you can call me bubba
 
That's how they did the one wire thing. The difference in the wiring is internal jumpers inside the regulator.
 
clutchdust said:
i just ran a wire off my charging stud to the #1 terminal to excite the regulator.
Click to expand...

The problem with doing this is that the regulator senses the voltage right at the alternator output, and not the voltage at the battery with the voltage drop that occurs through the length of cabling to the battery. If you have a C3 with a mid-mounted battery, or a car with a trunk-mounted battery, the voltage drop to the battery can be significant enough that the battery actually won't charge (the regulator will sense and control about 13.5-14.2 volts right there at the alternator output lug, but voltage at the battery can be below 12). If you do this jumper trick, or if you go with a 1-wire alternator, be sure to check the charging voltage at the battery terminals and not at the alternator. On cars with trunk-mounted batteries, I have gone so far as to run the sensing wire to the #1 terminal all the way back to the battery "+" post in the trunk. The difference in alternator charging voltage becomes dramatic...

Lars
 
lars said:
clutchdust said:
i just ran a wire off my charging stud to the #1 terminal to excite the regulator.
Click to expand...

The problem with doing this is that the regulator senses the voltage right at the alternator output, and not the voltage at the battery with the voltage drop that occurs through the length of cabling to the battery. If you have a C3 with a mid-mounted battery, or a car with a trunk-mounted battery, the voltage drop to the battery can be significant enough that the battery actually won't charge (the regulator will sense and control about 13.5-14.2 volts right there at the alternator output lug, but voltage at the battery can be below 12). If you do this jumper trick, or if you go with a 1-wire alternator, be sure to check the charging voltage at the battery terminals and not at the alternator. On cars with trunk-mounted batteries, I have gone so far as to run the sensing wire to the #1 terminal all the way back to the battery "+" post in the trunk. The difference in alternator charging voltage becomes dramatic...

Lars
Click to expand...

Tru fact. Without a true 14 volts or so impressed at the battery itself, sulfation/lower voltage/shorter battery life WILL occur. It's just a fact. The effect becomes more dramatic the further the battery and the alternator are located from each other.
On a 57 Chevy with the alt/battery 2' from each other, it would make little difference.
 
big2bird said:
lars said:
clutchdust said:
i just ran a wire off my charging stud to the #1 terminal to excite the regulator.
Click to expand...

The problem with doing this is that the regulator senses the voltage right at the alternator output, and not the voltage at the battery with the voltage drop that occurs through the length of cabling to the battery. If you have a C3 with a mid-mounted battery, or a car with a trunk-mounted battery, the voltage drop to the battery can be significant enough that the battery actually won't charge (the regulator will sense and control about 13.5-14.2 volts right there at the alternator output lug, but voltage at the battery can be below 12). If you do this jumper trick, or if you go with a 1-wire alternator, be sure to check the charging voltage at the battery terminals and not at the alternator. On cars with trunk-mounted batteries, I have gone so far as to run the sensing wire to the #1 terminal all the way back to the battery "+" post in the trunk. The difference in alternator charging voltage becomes dramatic...

Lars
Click to expand...

Tru fact. Without a true 14 volts or so impressed at the battery itself, sulfation/lower voltage/shorter battery life WILL occur. It's just a fact. The effect becomes more dramatic the further the battery and the alternator are located from each other.
On a 57 Chevy with the alt/battery 2' from each other, it would make little difference.
Click to expand...

Bird, remember my long winded argument with that PWM controller dude on CF, long time ago...some of you all backed me up in that farce....
he just could not understand that under certain driving conditions, meaning normal use, the battery would die a slo death, never getting a charge for his fans running off the battery direct....let along the fuse fiasco...

:shocking::p:beer:
 
a simple resolution for a 1 wire system would be to just have a pot you could adjust the regulation voltage with. Just bump it up while reading the batt voltage with a fluke to get the desired voltage at the batt.
 
turtlevette said:
a simple resolution for a 1 wire system would be to just have a pot you could adjust the regulation voltage with. Just bump it up while reading the batt voltage with a fluke to get the desired voltage at the batt.
Click to expand...

A simpler resolution for a 1 wire alt is a 3 wire alt.:devil:
 
big2bird said:
turtlevette said:
a simple resolution for a 1 wire system would be to just have a pot you could adjust the regulation voltage with. Just bump it up while reading the batt voltage with a fluke to get the desired voltage at the batt.
Click to expand...

A simpler resolution for a 1 wire alt is a 3 wire alt.:devil:
Click to expand...

Yeh, the legal equivalent of this would be Stare Decisus (sp?) or, it's been decided, let it stand....:lol::devil:
 
big2bird said:
turtlevette said:
a simple resolution for a 1 wire system would be to just have a pot you could adjust the regulation voltage with. Just bump it up while reading the batt voltage with a fluke to get the desired voltage at the batt.
Click to expand...

A simpler resolution for a 1 wire alt is a 3 wire alt.:devil:
Click to expand...


Well again for me its much simpler to put a 1 wire on than try to trace out the wiring to find out why the switched field power is not working.

I know that you think its much simpler and way way easier to remove the column from the car and do a total rebuild chasing the problem to find out its really somwhere else. What's the next step a frame off? :lol:

I can't wait for you to come out to Mass so you can tell me how full of shit i am in person.:drink:
 
Last edited:
Well again for me its much simpler to put a 1 wire on than try to trace out the wiring to find out why the switched field power is not working.
[/QUOTE]

And you diagnose control problems at nuclear power plants? That's scarey as hell right there.:devil:
 
You must log in or register to reply here.
Top