voltage regulator

[James O.]

Re: voltage regulator

howard- agree with everything said above. try a simple check working backwards. engine off. be sure your battery is known good and you should measure 12 to 12.5 volts right at the battery posts with an accurate voltmeter. then start engine and turn on lights and other accessories so ammeter shows the discharge you were seeing. now check the battery at the posts again with someone reving up the rpm. if that battery voltage shows 13-14.5 volts you are probably good. otherwise i don't think you have solved the problem yet. jim o.

[Dan D.]

Re: voltage regulator

Hi Howard,

Let me add a little here to what Jim has said.

A fully charged battery, just sitting, no load or charging, will be about 12.6 volts. You can measure this - right at the battery terminals. Start the engine, run the RPMs up until the generator 'breaks through' and starts charging. Monitor the battery voltage while doing this. The voltage will slowly rise. When the voltage rises to a little North of 14 Volts, the voltage should level off and stay there. It should not get any higher, nor should it drop down any. If it levels off before reaching 14 volts, then the regulator is adjusted too low and your battery will not reach full charge. There is an adjustment screw inside the regulator that is used to adjust this voltage.

Concerning the regulator, all there is in these old regulators are 3 relays and 2 resistors on the bottom. There is not a lot that can go bad. They can get out of adjustment, and the contacts can weld themselves together from arcing. One relay regulates the voltage, one the current, and one is the 'cut-out' relay. When the cut-out relay pulls in, generator current is connected to the battery and the system charges. That relay pulls in when the generator voltage exceeds the battery voltage. This is the 'break over' that we talk about.

There is one failure that can, and does happen, is when one of the relay contacts weld themselves together. This can cause the the system to put out full voltage and current which would overcharge the battery, burn up the generator, and even burn the wiring. To guard against this, the regulators have a built-in fail-safe. There is a small gauge wire that has a piece of black sleeving on it. It connects between one of the relays and a terminal. This wire acts a fuse and if this run-away condition occurs the wire burns in to inside the sleeving. This renders the regulator inoperable and it will not charge at all. Not many people know this, but it happens. If you tug on this wire a bit, the wire will pull out of the sleeving and you can see where it is broken.

Hope this helps - I think you are very close to being there.

-Dan-

[Frank D.]

Re: voltage regulator

The regulator adjustment procedures should be in the passenger car manual but, as suggested above, if the voltages check out OK, it is prob best left alone......