1956 charging problem - generator? voltage regulator?

[1956century]

I recently installed an air suspension system in my 1956 Century. There is a small compressor in the trunk and a digital display for the driver that also reads the voltage that the compressor is receiving.

I have yet to see the system ever go over 12 volts, it usually stays at around 10. Sometimes it even drops below 9 (car off). The battery seems to be holding just enough charge to start the car and drive, but nothing more. I left the dome light on for about three minutes and the battery was dead. I've tried a number of batteries that work perfectly in other cars.

The compressor is specially designed to not put a strain on the car's electrical system. When the compressor shuts off (after it pumps up enough pressure) the display usually reads around 11v, which leads me to believe that a charging component is not working very well.

I took a look at my friends '55 the other day - at first start, the amp meter would climb as he pushed the throttle. When it generated a sufficient charge, the meter stayed at the midpoint of the gauge. Now I haven't driven my car in a little while, but I don't think that the amp meter ever stopped climbing when I pushed the gas down. So even if I was 15 minutes into my drive, the amp meter still moved with the increase in RPM. From what I gather, this means that the generator is not making enough power or the voltage regulator is not working properly.

Any ideas? I really do not want to drop an alternator in there.

Thanks,

Alex

[buick5563]

Why? They have alternators that look original if that is the concern, but if you bagged the suspension anyway, it is already altered.

[Joseph P. Indusi]

Before you can determine if the generator needs servicing or the regulator needs to be replaced, you should do the following:

1. Charge the battery with an automatic charger (the type that automatically tapers off the current or goes to 1 amp or less) or a standard charger for at least several hours. Check to be sure that the plates are covered before charging. Fill with distilled water as needed. After 6-8 hours the charging rate shoudl be about 2 amps and with the charger disconnected the voltage should be about 12.4 volts or more. If the battery doesn't show it can take a charge then obtain a replacement or substitute.

2. Check all the wiring for good metal to metal connections especially ground connections for the battery and regulator.

Now, with the engine off, use a short jumper to connect the field "F" terminal on the regulator to a good ground. Start the engine and let it run at a speed above idle. Do not rev too high. The ammeter should show charge indicating that the generator is delivering current to the battery. Shut off engine and disconnect the jumper.

Restart the engine and see if the ammeter charge rate eventually goes down and the needle moves to the center. If not, I would replace the voltage regulator as either the voltage or current regulator sections are defective.

Good luck.

[d2_willys]

Before you can determine if the generator needs servicing or the regulator needs to be replaced, you should do the following:

1. Charge the battery with an automatic charger (the type that automatically tapers off the current or goes to 1 amp or less) or a standard charger for at least several hours. Check to be sure that the plates are covered before charging. Fill with distilled water as needed. After 6-8 hours the charging rate shoudl be about 2 amps and with the charger disconnected the voltage should be about 12.4 volts or more. If the battery doesn't show it can take a charge then obtain a replacement or substitute.

2. Check all the wiring for good metal to metal connections especially ground connections for the battery and regulator.

Now, with the engine off, use a short jumper to connect the field "F" terminal on the regulator to a good ground. Start the engine and let it run at a speed above idle. Do not rev too high. The ammeter should show charge indicating that the generator is delivering current to the battery. Shut off engine and disconnect the jumper.

Restart the engine and see if the ammeter charge rate eventually goes down and the needle moves to the center. If not, I would replace the voltage regulator as either the voltage or current regulator sections are defective.

Good luck.

Yep, do this first! About the only other thing to check is the compressor itself. Is it fused, and what is the fuse value? Point is, that the generators of the 50's usually only put out 35 or so amps when the battery was very low and needed charging. The compressor may be sucking most of the generator output and leaving the battery low all the time.

[Joseph P. Indusi]

d2_willys makes a good point. The compressor could be taking nearly all the generator can put out. I checked and according to Motors the current regulator set point is 34 amps for 1956 models. At the maximum current the charging voltage will be on the low side as well. I would check this system with the compressor disconnected or the fuse removed. Once the generator/regulator/battery are working OK the compressor can be brought into the picture.

Joe, BCA 33493

[Guest Koala]

With the battery fully charged and with the engine speed increased, the voltage at the battery should be between 12.5 and 13.8 volts if all is well.

Shorting the 'F' terminal as described in a earlier post will tell you the maximum voltage that the generator is capable of producing as shorting this terminal is effectively cutting the regulator out of the system.

Koala

[Alfa]

Just to add that the 35 amps or so max charging output that is mentioned above, will only be seen at quite high rpm, say 2,500. Most of the time you will be doing less than that, and therefore less charging amps.

If you are running a high current consumption load, you may need a generator that is battery sensing, not machine sensing, so that it delivers high output at low rpm. That is to say...an alternator.

Adam..

[1956century]

Before you can determine if the generator needs servicing or the regulator needs to be replaced, you should do the following:

1. Charge the battery with an automatic charger (the type that automatically tapers off the current or goes to 1 amp or less) or a standard charger for at least several hours. Check to be sure that the plates are covered before charging. Fill with distilled water as needed. After 6-8 hours the charging rate shoudl be about 2 amps and with the charger disconnected the voltage should be about 12.4 volts or more. If the battery doesn't show it can take a charge then obtain a replacement or substitute.

2. Check all the wiring for good metal to metal connections especially ground connections for the battery and regulator.

Now, with the engine off, use a short jumper to connect the field "F" terminal on the regulator to a good ground. Start the engine and let it run at a speed above idle. Do not rev too high. The ammeter should show charge indicating that the generator is delivering current to the battery. Shut off engine and disconnect the jumper.

Restart the engine and see if the ammeter charge rate eventually goes down and the needle moves to the center. If not, I would replace the voltage regulator as either the voltage or current regulator sections are defective.

Good luck.

Thanks for the instructions. I will try it and update this weekend.

I checked the specs on the compressor. It never pulls more than 16 amps of power (@13.8 volts), so I don't think it's a huge load on the system.

Thanks,

Alex

[d2_willys]

Thanks for the instructions. I will try it and update this weekend.

I checked the specs on the compressor. It never pulls more than 16 amps of power (@13.8 volts), so I don't think it's a huge load on the system.

Thanks,

Alex

50% of your maximum charging current is an awful lot, especially if the normal charging current is around 20 Amps on average.

[pirate]

The gen-reg charging system is a simple system. Do the before mentioned field check and determin if the problem is the generator or the regulator. 99% of the time it is one of these two and almost always it is the generator and almost always it is the brushes in the generator being either hung up or worn down. Changing brushes is an easy "common sense" job. Give it a try.

[1956century]

I have not yet conducted the tests specified in the above posts. I did, however, check the power coming from the generator with my multimeter - steady at 14v. I also noticed that my lights flicker after I let off the throttle.

I think my regulator is toast.

[Guest Koala]

14 volts maximum charging rate is within specs. but what is your reading with the headlights on??

It is normal for the headlights to be brighter with the engine revs increased because when the engine is at idle speed the generator is not producing maximum voltage and the regulator will cut out..........this results in the headlights running on the lower battery voltage at idle. Sometimes you can hear the regulator cutting in and out as you raise and lower the engine revs.

Koala