1955 Cadillac possible generator issues

[Cadillac Jack 82]

I ran into a slight problem this past weekend when getting my 55 ready to ship out west.  When using anything such as the radio or lights my generator light kicks on and stays on.  When I turn the lights or the radio off it appears to go away.  I assume this is a sign that my generator is on its way out?  If this is the case does anyone happen to have the proper generator or regulator that I'll need for my car?  I have A/C.  Thanks.

[signart]

Does this happen at idle or while operating?

[Cadillac Jack 82]

Mostly at idle but there is a faint glow during operation if I'm using headlights or the radio.

[fishnjim]

More likely the VR.   It's not responding to load.   The contacts can corrode sitting around.
I guess you're a few days away from a dead battery.   It could be the battery, bad cell, causing low voltage.
Take to an auto electric shop or test the charging system.   If you don't know how or no equipment,  the local chain parts stores can do it.   No biggie.   Gen light works OK!

[Cadillac Jack 82]

Battery is brand new so I know its not that.  Does anyone have the Delco code for the correct style of voltage regulator?

[J. Gomez]

Battery is brand new so I know its not that.  Does anyone have the Delco code for the correct style of voltage regulator?

Tim,

A slight glow of the “GEN” at idle with no load and in “D” is normal, this is due to the very low RPM for the generator to charge. If you add a load and the light turns “on” at idle RPM in “P/N” it may be either the battery is weak or the regulator may need adjustment.

There may be a chart on the Service Manual that shows the presetting for the VR adjustment, not sure if you had check the voltage at the battery?

The VR per the MPL is the 1118825 or 1119003 30A w/or w/o A/C

Good luck..!

[Lexi]

Agree with Jose. Not sure what your comfort level is in running tests with a multi-meter, as well as conducting tests on your battery's state of charge. In the past when this has come up I have suggested to purchase an inexpensive portable volt meter that you can plug into your cigarette lighter. That way you can see what your charging system is doing at varying loads, even when out on the road. See attached pictures. Available from Amazon I think for under $20. I got one for my car, as in the photos, a "VST 3IN1". Gives voltage, cabin temperature (a fluffy not needed function), as well as a port to accept a USB connection. So while driving down the road watching your voltage reading which lights up by way of LED illumination, (highly visible even at night), you can even plug your phone or a GPS into it to run or for a charge. When done, just unplug and put your cigarette lighter back in. The round faced designs seem to better suit our '50s Caddies.

When starting my car on at least a weekly basis in warm weather, I seem to recall on fast idle it will read in the 13s, then quickly rise to the mid to high 14 voltage range. Think that would be around 1700 rpm. It may also creep into 15 - 15.2 volts. Over 15 seems on the high side, but my wet cell battery in 3 years has not shown adverse signs of over charging such as reduced electrolyte levels. You can see it fluctuate when accessories are turned on or off like the radio or power windows. Driving around town which includes sitting at lights I would say the voltage readings are usually at least in the mid to high 13 volt range. A battery restorer once told me that if you average below 13.0 volts you are heading for trouble, as your battery will eventually go flat. On the highway if memory serves, think I was at around 14.4 volts, or a touch more.

It is a good, inexpensive accessory to have. It is always nice to know what is going on under your hood, and unlike a hand held volt meter, this one gives you some idea of what is going on when your car is being driven. Also, if you are so inclined, GM produced some informative service related manuals on their charging equipment that cover our era of cars. The "Delco-Remy Electrical Equipment Operation and Maintenance Handbook", item number DR-324A (a supplement to the 13th edition of DR-324), is very useful. It seems to cover at least the years 1954 - 1957. Also, though far less technical, was the short handbook "The Charging Circuit", item #UM-300, (of which there are 1950s editions of). These do pop up on Ebay and also at car shows. Hope some of this helps. Clay/Lexi

Edit: Generator output is not as efficient at low speeds, so some of your concerns may simply be related to that and be normal as per Jose's comments. The shop manual may help somewhat with respect to servicing. There are currently replacement VRs available out there, and still those who can rebuild a generator.

[signart]

Won't add to the advice above except the first thing to check, and it takes 2 seconds, is your belt tension.