Vintage Oldsmobiles Curved Dash, Limited Touring, Models 40, 53, 66; Series 60, 70, 90

Ammeter Question

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Old Apr 19, 2013 | 05:05 PM
  #1  
starfire's Avatar
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Ammeter Question

Hi, new to the world of generators. 1949 98 4-door. Original 303 with original generator. Everythings original. When at idle without lights on the ammeter stays in the middle. When driving, the ammeter goes up towards +30. When I turn the headlights on at idle, the ammeter goes down very close to -30, but comes back up when driving. Is it normal for the ammeter to go so low when lights are on at idle?

Thanks,
Old Apr 19, 2013 | 05:15 PM
  #2  
MDchanic's Avatar
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Yes. Generators are notorious for not really charging at idle, which is one of the reasons why they were replaced by alternators as soon as solid state rectifiers became cheap and reliable (the other reason is weight).

- Eric
Old Apr 19, 2013 | 08:10 PM
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Just to be sure clean your battery terminals and ground straps. If your battery is weak it will be more pronounced.
Old Apr 23, 2013 | 02:22 PM
  #4  
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1956 holiday coupe
 
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A little off topic and pricy but have you guys seen this? Great for you original nuts out there.
http://www.ebay.com/itm/59-60-61-62-...8728fa&vxp=mtr


Last edited by hialeah56; Apr 23, 2013 at 02:24 PM.
Old Aug 4, 2013 | 08:34 PM
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Battery cables are brand new and all connections are clean and tight including the ones on the generator. Voltage regulator is new. After driving with the lights on for 15 minutes or so and another additional 45 minutes without the lights, check the battery and it reads 6 volts. Put the tester on the battery and run the engine, it reads 6 volts. Increase the throttle to approx. 2000 rpm and the meter moves up to 6.2 volts. This does not seem to me to be enough. Seems like at 2000 rpm the generator should be putting out 6.7 to 7.0 volts. Am I expecting too much?

Then shut off the car and put the battery charger on it, charger says the battery has 81% of a charge. The charger is able to charge the battery back up to 100%.

Should I be looking at the generator as a problem here, or is this just how it is? I know a generator isn't as efficient at recharging as an alternator is, but it just seems to me it isn't working properly.

Thanks for the link to the alternators that look like generators, would like to go with one, but they are all for 12 volt systems.
Old Aug 4, 2013 | 08:53 PM
  #6  
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You may have a weak battery, it should read 6.3 volts fully charged. Your generator should be putting out around 7.2 volts. Generators will start to charge at around 800 rpm.
Old Aug 5, 2013 | 02:53 AM
  #7  
MDchanic's Avatar
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Could also be your regulator.

I would hot-field the generator and see whether it has good output when asked to
(short Batt and Field terminals for a moment and watch the voltage).

- Eric
Old Aug 5, 2013 | 04:29 AM
  #8  
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Originally Posted by MDchanic
Could also be your regulator.

I would hot-field the generator and see whether it has good output when asked to
(short Batt and Field terminals for a moment and watch the voltage).

- Eric
Batt and Field on the regulator?
Old Aug 5, 2013 | 05:58 AM
  #9  
MDchanic's Avatar
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Yeah, if you disconnect the Field wire from the regulator, and touch it to the Bat terminal, a voltmeter placed between the Bat terminal (at the generator or at the battery or at the regulator) and Ground should show the voltage go right up to about 8v.

- Eric
Old Aug 6, 2013 | 01:30 PM
  #10  
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From: Santa Fe, New Mexico
Just change it to 12 volt system, Thats what I did to my 50 Olds. Generators don't charge except on long drives. They really suck. I've changed over both my 50 Olds and my 48 Plymouth (9this one was a challenge 6 volt positive ground).
50 Olds
Old Aug 6, 2013 | 01:51 PM
  #11  
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That is awesome!
Old Aug 19, 2013 | 05:56 AM
  #12  
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From: 1248 Riverwood Drive. Nashville, Tn. 37216
Different topic. I bought a set off those wire looms from Shinny Hinny and the bolt pattern for the covers and the looms are different. How did you solve that problem.?
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