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Voltage Regulator Settings
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Packard 1948
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Hello Cyber Packard Friends!!!

I hope you all had a Happy Christmas and/or are enjoying Hanukkah.

Over the holiday break I got to play around with my dad's 49 Packard. It is running really good after the engine and transmission rebuild last year. Man...I am here to tell you that that thing fired right up at 35F and ran super smooth and purrs like a kitten...smoothest running carbureted car I ever remember seeing.

Anyhoo, I was wondering if I could ask the collective about voltage reading during cold and warm charging and ask to see if my readings are in the ball park with what they should be. I know that the VR can be affected by cold/hot temperature so I ran the test at both hot and cold and low and high idle with headlights off/on. I know the VR is working because the ammeter needle swings right and flickers correctly however it looks like perhaps the current limiter relay may be cutting the charge off a bit earlier that I would like to see.

Since the engine fires right up there is very minimal drain on the battery by the starter motor.

Here were my digital volt readings:

Cold battery (not run for three days) before start: 6.49

Measurements with system cold (about 40F outside air temp) immediately after engine start:
Headlights OFF / Headlights ON
High Idle (choke on) 6.80 / 6.93
Low idle (choke off) 6.30 / 6.18

Measurements with system warmed up:
Headlights OFF / Headlights ON
High idle 6.68 / 6.55
Low idle 6.30 / 6.19

So yes the system is working however I thought it would be putting out a bit more voltage.

Do these look close?

THANKS VERY MUCH for your help!!!


Posted on: 2016/12/28 19:49

Dedicated to keeping the man who owns one on the road!!!
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Re: Voltage Regulator Settings
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Fish'n Jim
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If the light aren't dimming noticeably or too bright, I wouldn't worry about the voltage readings whatsoever, so long as they're above 6-6.2V and it fires off.
There' no way to tell how old the battery or generator is or how the VR is set over the internet. You can always take to an auto electric shop and have them check things out with the proper tools.

Posted on: 2016/12/31 13:30
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Re: Voltage Regulator Settings
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Rusty O\'Toole
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Should be 7.2 volts on a 6V system. Your readings will be lower if the battery is connected especially if the battery is a bit low.

Instructions for testing and adjusting can be found in any good repair manual. They vary slightly by the manufacturer of the electrical equipment.

If you want some boring details... a fully charged wet cell is 2.2 volts so your 3 cell battery is actually a 6.6 volt battery, but only if fully charged and in perfect condition.

To get the battery to take a charge the generator output must be higher than that, but not too high. 7.2 volts is plenty.

Posted on: 2016/12/31 16:24
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Re: Voltage Regulator Settings
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I first used an Optima battery in my '50 Packard sedan. never had a problem in the 11 years I used it. That was around 1990 through 2001 or 2002. I sold it and it still might be still going strong. Either way great battery!


Posted on: 2016/12/31 16:45
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Re: Voltage Regulator Settings
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Fish'n Jim
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http://batteryuniversity.com/learn/ar ... ing_the_lead_acid_battery

Normal lead sulfuric acid is the number of caps(cells) times ~2.1 for total voltage, ~6.3V.

Posted on: 2017/1/1 14:59
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