Possible alternator and or voltage regulator issues?
Hey 67 finally got a chance today to do some trouble shooting. So i remembered the guy my dad works with had give us a motor brand auto repair manual for 66-72 ford chevy chrysler dodge etc vehicles. And looked under the testing the voltage regulator section for wiring with an isolated field alternator. Also said to check with engine running at 1250 rpm and to place the black lead of the volt meter to ground and to take the positive lead and check voltage at the voltage regulator side of the ballast resistor. Normal voltage spec at that point should be 13.8-14.4 volts and if there was a difference of more than .5 volts than specs at that test point to replace the voltage regulator. So i fired her up and within 5 seconds or so we were reading 18 volts. Just to double confirm the manual the regulator is bad correct? Also i have a factory style on it now with the chrysler insignia are those ok or are there any better options thanks so much for your help
I'm not sure what you did here so let's clarify.
There's several reasons that charging voltage could be high
1.....Voltage drop in the ground circuit. What this means is, the regulator is not truely grounded to the battery negative, see below.........
2.....Voltage drop in the ignition harness which is VERY common
3.....Regulator out of spec, IE trying to regulate but high. This is far more common on the older mechanical ones
4.....In rare cases, a battery going bad. Easily checked if you can just swap in a known good battery
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To check all of the above, and what you MIGHT have been checking with your meter
A......To check the ground circuit, get the battery charged, engine warm, and battery normalized. Run this check with all accessories off, and again with heater, lights, etc turned on.
With your meter on low DC volts, stab one probe into the regulator mount flange. Be sure to stab through any paint, chrome, rust. Stab the remaining probe into the top of the battery NEG post. What you hope to read is a VERY tiny voltage, the less the better, and zero would be perfect. More than .3V (three tenths of one volt) means you need to improve regulator ground
B......To check harness voltage drop, find the "high" side of the ballast IE the "key" side Turn the key to "run" but with engine OFF. Measure this voltage to the battery NEG, and subtract it from the battery voltage. As in B1, below, you are hoping for a result no more than .3V (three tenths of one volt)
B1.....A quicker, more direct way, is to find the "high" side, and leave your probe on that terminal. Move your ground probe to the batter POS terminal. As in the ground check, you now hope to read a very LOW voltage, the less the better. More than .3V means you need to improve the ignition harness circuit.
B2.....I'm not really sure but I THINK you checked the above in a third manner. With the engine RUNNING, if you measure the "high" (key) side of the ballast, then measure the battery, this voltage difference will be the same as in tests B and B1. In other words, if you measure, say, 14.2 at the ballast, THIS IS what the regulator is regulating TO and is "correct." But if the battery shows HIGHER, then this shows you do have voltage drop in that ignition harness / ground circuit.
Common problems in this harness are the bulkhead connector, ammeter and connections, and ignition switch connector or the switch itself.
PLEASE read this:
http://www.madelectrical.com/electricaltech/amp-gauges.shtml
WHY this voltage drop is important: The regulator gets power through the ground circuit and the ignition harness circuit. Let's say between the two of them, there is a 1.5 V drop. This 1.5V gets ADDED to the battery charging voltage because the regulator "senses" whatever voltage is at it's terminals.
This means if the regulator is actually "correct" at 13.8--14.2, this 1.5V drop gets added to say, 14V so the battery now sees 14 + 1.5, or 15.5V