Packard Forum Index » Post-War (1946-54)

alternator wiring.
Hello,
I purchased a one wire 6 volt alternator on e-bay along with the voltage regulator. However I have no clue how to wire it to my 1951 300. The regualtor has terminals marked: bat, fld, and arm. Your help would be appreciated since my 300 runs fine except after I drive it and the it sits for a couple of hours, the starter cranks slowly.
Thanks,
Casey Rog

A prior owner had my car converted to 12 volt negative ground and installed an alternator. This alternator has two wires coming from it and unfortunately they disappear into a wiring loom. I suspect the heavier wire joins the battery cable at the starter motor and the lighter wire supplies the "Gen" light on the dash, but perhaps someone better versed in this could advise you more authoritatively than I can. I do know that the vast majority of alternators are regulated internally and do not use external voltage regulators. The regulator you describe is clearly for a generator and would be useless if you install an alternator.

Before taking that step I suggest that the electrical system should be checked. The battery might be on its way out and should be load tested. The system should be checked for drains or draws such as a trunk or glove box light staying on and draining the battery. With the condition present, the starter motor draw should be checked. If it's taking too may amps to function on a warm restart, an alternator will not correct the condition and the starter motor will still have to be rebuilt or replaced. Of course, the generator output and voltage regulator performance should also be checked. If either one is faulty, I'd recommend rebuilding/replacing them instead of installing an alternator. Your car's generator was designed to provide sufficient current to run the car as originally equipped. Only if I were going to install some high-draw accessory such as an electric radiator cooling fan or a modern resistance-type rear window defogger would I even consider replacing the generator with an alternator.

Another remote possibility for slow cranking on a warm restart is tight bearings in the engine. Has it just been rebuilt? If so, the condition should disappear as the engine breaks in.

I hope you can find the cause of the slow cranking quickly and easily. Good luck.

Just a question

If the voltage regulator was purchased with the alternator, is there any chance that it had been modified/altered to work with the alternator and retain the original looks?

Can you ask the person that sold you these items? He may be the only one that knows what you were sold.

A one wire alternator should be internally regulated. I have a one wire unit on my 38 and I run the wire to a fake regulator box (ran a jumper from the bat to the output) and then to my amp meter. I hooked the arm and field wires to the regulator just for looks and the other ends just go nowhere.

Are the car and alt pos ground? I also think a 1 wire alt is internally regulated. If so I think all you do is connect the 1 wire to the battery terminal of existing regulator and disconnect the other wires going to the regulator. I am sure someone will correct me if wrong

Thanks Don,
I checked the output of the generator and regulator which I also bought on e-bay as a rebuilt and "sealed" replacement.
It was putting out 7 volts, but only 7 to 8 amps at medium speed. I replaced this unit with the unit that came with the car and am getting 7.5 to 8 volts and 8.4 to 9.4 amps at medium speed.
I will not replace the generator, but keep checking the output on the existing.
Thanks again,
Casey Rog

How did you measure the amp draw?

Hi Casey,
The amp readings of either generator look good and the battery seems to be holding its own also, assuming no major electrical accessories were on when tested. You might want to see what the output is with the high beam headlamps on (14 amp draw) and the under dash blower fan on high (10 amp draw.) I'd let the car idle for a little while with both accessories on to deplete the battery some and then rev the engine over 1000 rpm and see what the generator is putting out with those loads. If the output rises proportionately then the generator seems to be OK and the cause of the slow crank on a warm restart most likely lies elsewhere.

I note that the specs for '51 call for a 40 amp generator, changing to 45 amps in '52 and up. I'm thinking they did this in anticipation of the return of air conditioning as a factory installed option.