Swapping out a generator for an alternator

With delcos, the idea of the resistor, is to give a second path for power if the lamp burns out. It is run parallel to the lamp. The value has changed over the years, but is not critical, it is just so power will go through the lamp first, but still provide a path if the lamp burns out.

Ignore the stuff inside the dashed lines, those are internal to the alt, and may be different on yours. The switch is your ignition.

imagealt1.gif

Romaine is a distributor. Look for a model number, or posy pics of the back, I may be able to narrow down what it is.
 
After printing out the circuit diagram I had to look over the wiring to find out why
the ammeter was seemingly dead. I removed it and cleaned it up and then tested it and
it works just fine. Also I had suspicions about the circuit breaker that is next to the ammeter.
It turned out to be an open circuit and the bimetallic disc with the silver contacts was rusted
away. That explains why there was a heavy wire from the positive terminal of the starter
going to the regulator. Someone apparently couldn't find the problem and bypassed
everything to make the machine operational. I disconnected the heavy wire on both ends
and temporarily bypassed the circuit breaker. Now everything works as it should including the
ammeter! I have a bunch of circuit breakers I salvaged at the scrap yard so tomorrow I
can finish up and install the breaker. I started up the CAT and the alternator was charging
at about 15 amperes after the initial charge sequence so all is well there.
 
Superburban said:
With delcos, the idea of the resistor, is to give a second path for power if the lamp burns out. It is run parallel to the lamp. The value has changed over the years, but is not critical, it is just so power will go through the lamp first, but still provide a path if the lamp burns out.

Ignore the stuff inside the dashed lines, those are internal to the alt, and may be different on yours. The switch is your ignition.

View attachment 377707

Romaine is a distributor. Look for a model number, or posy pics of the back, I may be able to narrow down what it is.
Click to expand...

Thanks! I will take a better photo of the alternator and hopefully find some ID on the unit. I will try to post
again later today with a photo and some information.

Edit: I looked on my E-Bay and the brand name is Gladiator.
 
Last edited:
So, for those of you in the know, what is the deal with adding a diode or two in series with the exciter wire?
It looks like to me that one can up the charge voltage by adding a diode or two in series with the exciter wire
and boost the output voltage. I am getting a charge current of 30 amps on startup but it drops off quickly...
 
Should it not drop off as the battery charges. Check it with a voltmeter, when it drops off the battery could be at 14.7 volts.

Greg
 
cathead said:
So, for those of you in the know, what is the deal with adding a diode or two in series with the exciter wire?
It looks like to me that one can up the charge voltage by adding a diode or two in series with the exciter wire
and boost the output voltage. I am getting a charge current of 30 amps on startup but it drops off quickly...
Click to expand...
Its usually resistors. It all depends on how the voltage regulator works. Some sense the voltage off that second wire, so a resistor will drop that voltage coming back, and cause the alt to put out higher voltage to compensate. Most just use that wire to start the alter, and do the actual sensing at the output wire, so dropping the extra wires voltage will do nothing.

30 amps dropping off quickly is ok, especial with older batteries.
 
I've used diodes on the field wire to stop the dreaded GM run-on. Works the first time, forever.
 
My hydrometer says the batteries are only at half charge so I'm considering adding a couple diodes in series with
the exciter resistor to coax the alternator to boost the charge voltage a little. I did some reading on the web and
it looks possible. Each diode would drop the indicated exciter voltage by 0.7 volts. It would depend on the
regulator circuitry I would think so it will be an experiment to see what happens. I love experiments!:grin:
 
You must log in or register to reply here.
Back
Top