1970 F100 not charging.

[fordrebuilder]

Hello everyone, I have a 1970 F100 302 3-speed with ammeter in instrument cluster that is not charging. I have performed a full field test on the alternator to make sure the alternator is functional and this passed. Next I made sure that the BAT connection at the back of the alternator was getting power, which passed. Next I checked resistance in individual wires which all passed. This led me to believe that I had a bad voltage regulator, 3 voltage regulators later I have no change in performance. I even connected one of the VR's directly to the negative post of the battery and had no change. This is the only electrical issue in the truck, all lights work, blinkers work, instrument cluster lights work, gauges work, wipers work, blower motor works. Does anyone have any insight on what this problem could be?

[cep62]

Sometimes the gauges are bad.
Get a volt meter and check it at the battery.
A fully charged battery should be around 12.5 volts and charging around 14.

[fordrebuilder]

I haven’t been going by the gauge, only checking with a voltmeter.

[FORDification]

I always hate to be the one who says "check your grounds", because that seems to be what everyone says...but it's an honest suggestion. Corroded grounds will do weird things. Make sure the engine is properly grounded, from firewall to intake manifold, from block to frame, from battery to frame. Make sure all grounds for alternator and voltage regulator are clean and tight, don't just assume, check 'em and clean 'em. Make sure the battery cables and clamps are clean and tight. The cables will often corrode inside under the insulation, where it's hard to see. And make sure the battery is good and can actually accept a charge. Have a load test done.

[fordrebuilder]

This issue is now solved, after getting the fourth voltage regulator I finally got one that worked. I feel $40 is a rather high price for something that only has a 25% chance of working.

[cep62]

Good deal ! Thanks for the update.
That's a good excuse to have multiple vehicles.
So you can swap known good parts and help with diagnostics .
I keep trying to explain that to my wife.