I posted on this subject recently, but want to start clean with this one. I have a '53 F100 with six-volt positive ground electric. Based on a recent bench test, my generator is fine. My voltage regulator is brand new, as is all the wiring. The battery is brand new and fully charged. The generator has been polarized. I just added some new ground straps, and the ground path between the generator and regulator and the battery is solid. Upon starting it up and running at low idle, the needle on the dash gauge stays right in the middle. I can see the needle move to the charge side a little bit when I rev it up. When I turn on the lights or wipers or heater fan, the needle moves to the discharge side. I was told that this is not what I should expect. I was told that I shouldn't see any movement of the needle when I turn on the headlights. So, what is there left to check? The wiring is sound. As far as the charging circuit goes, it's pretty simple: a straight shot from the battery negative terminal to the BAT terminal on the voltage regulator. It's a new regulator, but I suppose it could be defective... Maybe part of the problem is with the gauge, but that wouldn't explain seeing the needle move when I use light, fans, etc. I will read through the shop manual, but I am inexperienced using testing equipment, so following up on any procedures that requires the use of testing stuff may be a problem for me.

 

Every real gauge I have ever had moves a bit toward the discharge when I put a draw on the system. It should not go into the discharge, but you should be able to notice a minor fluctuation. You should also see it climb back up as you increase engine speed.
If you are going all the way into discharge with just the lights, what does it do when you put a full load on it, (lights, heater, radio)? Even with this all on, at about 2000 rpm, you should still be charging.
Grounds are the most common culprit for electrical problems. Make sure everything is properly and firmly grounded before you pursue any other trouble shooting.

 

Without a meter and basic knowledge, it is impossible to troubleshoot electrical problems. Using A meter to find out what you need to know here is not difficult or time-consuming.
Get one and we can talk you through what you need to know. The ampmeter on the truck is not much at troubleshooting. And yes, with full electrical load the ampmeter may read discharge.

 

The new regulator could very well be bad. It is certainly not unheard of.

 

Remember that the generator system is not charging at idle, if you were to have a full tank of gas the battery could in theory die before running out of gas. RMP needs to be increased as stated. You need a good multi-meter gage that reads volts to see what is wrong.

 

If I remember right (and I may not) you had an auto electric shop set up the regulator and generator together, that's a good thing.

Would recommend purchasing the Ford Shop manual for your truck, there's a section on generator and regulator testing. Make sure the charging voltage and amps are correct at spec in the chart when actually installed in the truck. It is temperature dependent. MoToRs manuals are excellent for troubkeshooting as well. As mentioned previously it's important that the charging circuit and ground connections are clean and tight (remember too generator must have solid electrical connection to block) and no paint or corrosion is present. Maybe you know all this already.

 

I don't think you have a problem. The needle on my 55F350 moves just as you described.

 

After starting, the battery is discharged. You should see the needle move quite a bit to the Charge side until it is replenished, at 1500 RPM. At regular idle, -0- isn't bad.

This is true at 1500 RPM. At idle the generator doesn't put out much if any, so yes, it will swing to Discharge. If you then rev it to 1500, it should swing to Charge for a while, then settle to -0- once the energy used at idle is replenished.

Is this what you're seeing?

Do I remember correctly that you recently re-wired the truck?

 

Reading it didn't sound to me like a problem either.

JB

 

The person giving you info probably isn't familiar with generators. Alternators work differently and can produce fair amounts of current at idle speed. The difference between generators and alternators are that generators have rotating stators and stationary fields whereas alternators are the opposite. The heavy rotating stators of a generator can only spin so fast before flying apart and/or the brushes begin to lose the ability to carry that current away from the commutator. Because a generator can only spin so fast the pulley ratio limits their maximum rpm, unfortunately causing their idle speed to be too low to create useful current. Alternators, on the other hand, utilize lighter rotating fields that require much less current and slip rings (vs. segmented commutators) that the brushes can easily follow. Thus they can use faster pulley ratios which increase the alternator's rpm at idle and provide quite a bit of current.

 

Beav,
I knew that alternators produced electricity at idle speeds but never knew why. Thanks for the lesson.