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Should stock alternator show 13-14.5 volts on a multimeter connected to battery?

Started by WH23G3G, April 28, 2015, 07:11:33 PM

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WH23G3G

While checking the charging system on my Charger and Valiant with my digital multimeter set on the DC setting should it show 13-14.5 volts while the engine is running at idle? I haven't checked it on my Charger but on my 65 Valiant 170 it only shows 11.82 volts when I have the multimeter connected to the battery while the engine is running at idle. My mechanic told me it's charging but not enough. So I replaced the alternator under warranty. It's only a 35amp on the 65 170. But even with the new alternator it's only putting out 11.82 volts running. I've replaced the engine/light harness and dash harness from Year One so all the fuse blocks are clean and connections clean. The voltage regulator is an aftermarket electronic updgrade that's maybe two years old now. Ballast resistor is about the same. It's still running points on my 65 170 so my mechanic said that will affect the performance too if it's not getting enough power. But the car runs good. I also have had all the gauges recored and recalibrated from Instrument Specialties and even the ammeter gauge was NOS. I'm wondering if it's doing the same on my Charger. Are the bolts that secure the voltage regulator to the firewall part of it's ground? One of them is stripped on my Valiant so it doesn't tighten all the way down. Just wondering. If I can figure this out I can get this Valiant on the road too.

Pete in NH

Hi,

The early Chrysler alternators did not produce much output at idle. I would run the engine speed up to 1500 RPM and measure the voltage. You should see something between 13.8 and 14.5 volts. Your 65 Valiant should have a single field wire alternator, one green wire, if it is a stock system. You mentioned an electronic upgrade, so if you could post some pictures of the regulator that would help me understand what you have on the car. You mentioned one of the regulator mounting screws is stripped. Those screws do ground the regulator and it is very important that they be clean and tight, no rust or paint in the way.

What does your dash ammeter show? does it ever move to the right as you speed up the engine?

new2muscle

 13.8 to 14.2 is industry standard for most charging systems. Sounds like you may have a bad ground, or a bad regulator. If it doesnt meet that range above an idle, something isnt doing its job. I would try re-grounding the alternator and regulator first, before you swap out anymore parts. Hookup a test lead from case to a known good ground and see what happens.