New electric fan killing battery

Sweet!

 

Glad you got the issue solved! You just had an alternator that was not capable of handling extra loads of elec. fans and such. I been running that unit and get 14+ volts no matter what devices I have on, from idle to cruising speed.
Also, you get rid of all that 40+ yr. old harness and regulator. A win-win situation IMO.

 

To measure high amperage with a simple volt meter:
Put a 1.0 ohm high wattage resistor in series with the circuit, and measure the voltage across the resistor - the reading is the amperage. Slight drawback is that the added resistance lovers the actual amperage. (Not by much)
Put a 0.1 ohm high wattage resistor in series with the circuit, measure the voltage across the resistor, multiply times 10 - that is amperage. Added resistance in the circuit is very-very small.

 

Rig went down to 11 volts while freeway cruising.

Idiot like never came on. Hmmm, found out the belt was glazed and slipping like whale **** on an ice flo (despite the
tension being good). The chirp/squeal at the 2-3 shift should have tipped me off, but what can I say....I'm getting a bit slow .

The 100 amp 10si puts quite a strain on a small 3/8" belt with an overdrive (smaller) pulley, so over a decade of service ain't that bad. Decent load on it too;
-halogen lights
-2 amps running 4 speakers and a sub
-electric fan
-MSD sparks
-nos solenoids
-nos bottle heater
-heated seat pad (winter months)

Installed a new belt and am back in business.

 

Update, things went down the drain again.
Even with the new belt on tight, I'm back down to 11.5 volts at idle with the lights and radio on. Turn lights off and it goes back to around 13.2 (used to go back to 14.2 with no load).

Something else must be going on. Took apart the unit...looked ok inside. Nothing visible anyway. Put continuity meter on stator and rectifier....checked ok.

Thoughts?

 

You removed the stock voltage regulator right?

 

Affirmative, I pitched it when I installed the 10si. Have it wired as a standard 3 wire (voltage sense, idiot light, and main battery output). I've been running the set up for about 15 years. A few years ago I freshened it up with new regulator, brushes, diode trio and rectifier.
Still looks good inside. The overdrive pulley has it spinning about 400 rpm more than stock for more idle output.

 

where are you checking the voltage at and with what tester?

 

The cabin digital gauge tipped me off to the low voltage condition, so I checked it with the digital multi-meter at the battery and it confirmed the reading.

 

Swap it out for a 3G alt so easy to do i put a 130amp on my 306 never drops

 

I've been eyeing the 3G's and even the CS144. However, now it's gotten personal. It has now completely died.
Put in regulator...zip, idiot light comes on and no charge above battery voltage.
Put in another rectifier, nada, still dead.
Brushes are ok.
Clean up slip rings, ok no grooves.
Diode trio passed ohm meter test.
Tested stator, no shorts that I could find.
The rotor doesn't seem to be shorting.

Now I just want to know the problem out of shear spite and pissed offness. Even if I end up chucking it off a 1000 foot cliff.

 

personal...I know how you feel....had a C-4 once that almost took me over the edge....

 

Are checking front to back ratio on each rectifier or just checking for shorts?? I've seen open diodes that caused low to no output... If that Delco is like the Fords, the rotor should be energized with ign on(not running), can test with a steel feeler gauge to see if shaft at pulley nut is magnetic...

 

Mostly just checking for shorts. Changed out the rectifier because I found a diode had busted away from the heat sink.
The "old" rectifier was a working unit, but after installation....no effect. Charge is zero and idiot light is at full landing light intensity.
The rotor had a pull even when disassembled, but I'll try the installed test today.

Thanks KC.

 

Tested magnetic field. Yes, when ignition key to "on" the front shaft pulls the shim toward it. So it is getting energized, but idiot light is still coming on. Started engine, but no charge. Gauge reads about 12.1 v.

Tested power lead and it had .4 ohms (about nominal for most of the other wiring) so that would seem to be ok, no blown fusible link.