I've plugged an inexpensive volt meter into the cigarette lighter in my 71 Fury. The battery, after sitting all night, is usually between 12.6 and 12.7 during the warmer months of the year. When the car is running shortly after start up I see voltage around 14.9 with brief spells at 15 or even 15.1. As the car warms up the volts will gradually settle down to between 14.5 and 14.7 with the brake lights on. When the brake pedal is released the voltage will often return to 14.9. I rarely drive with the lights or A/C on and don't use the heater much although everything works fine. I have done the under hood ammeter bypass mod and have done my best to keep all accessible connections clean. The battery seems good with no noticeable loss of electrolite. I checked the voltmeter in my newer daily driver and it's always steady at 13.9v. My question is, do I consider replacing the voltage regulator in the Fury? Is it overcharging? Thanks in advance for any advice.
Voltage from regulator too high?
- Thread starter 71FuryGC
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Sixpactogo
Well-Known Member
If you have a digital Ohmmeter, take a reading between Battery Neg and the case of your regulator. I bet you get a high reading. Should be less than .5 ohms.
How much have you driven your car of late? IF the existing battery is not fully charged. I mean "fully charged" as if you have driven the car 50 miles or so, or left an automatic-cut-off battery charger on it for several hours at low-charge rate. Unless the battery is fully charged, it is possible that you can see the readings you are seeing. Also, the battery needs to be reasonably new, too.
As a comparison, I have a 2005 LeSabre Limited that I keep the "Gauges" function on the Driver Info Center set on "Volts". Many times, it will read 14.7V to 14.9V as a normal situation. It's been pretty much like that for the 5 years I've owned it. I use it as a back-up car and it has a now-5yr old ACDelco battery in it. Sometimes, it will drop to 14.2V momentarily.
Used to be that we considered anything over about 14.2V as over-charging, with about 13.2V more normal with the engine idling. BTAIM
ALSO, ensure the battery posts and related cable ends are CLEAN, not just look clean, but are completely clean and fresh. A compromised interface there can be extra resistance, which can lead to higher charging rates.
Is the car being slow to start or the starter turning slower than it used to? For added confidence, you might take it to a shop and request a Charging System Check. That way, that check will test the alternator for output on the car. If it passes that check, as to amps and volts, it might help to justify what you are seeing?
Rather than your plug-in checker, you might consider a quality aftermarket gauge mounted in a spare area?
Just some thoughts and observations,
CBODY67
As a comparison, I have a 2005 LeSabre Limited that I keep the "Gauges" function on the Driver Info Center set on "Volts". Many times, it will read 14.7V to 14.9V as a normal situation. It's been pretty much like that for the 5 years I've owned it. I use it as a back-up car and it has a now-5yr old ACDelco battery in it. Sometimes, it will drop to 14.2V momentarily.
Used to be that we considered anything over about 14.2V as over-charging, with about 13.2V more normal with the engine idling. BTAIM
ALSO, ensure the battery posts and related cable ends are CLEAN, not just look clean, but are completely clean and fresh. A compromised interface there can be extra resistance, which can lead to higher charging rates.
Is the car being slow to start or the starter turning slower than it used to? For added confidence, you might take it to a shop and request a Charging System Check. That way, that check will test the alternator for output on the car. If it passes that check, as to amps and volts, it might help to justify what you are seeing?
Rather than your plug-in checker, you might consider a quality aftermarket gauge mounted in a spare area?
Just some thoughts and observations,
CBODY67
I keep the battery hooked up to a Battery Tender Jr most days and always disconnect the negative terminal when the car isn't being driven with one of those green threaded brass connectors. It floats at 13.3v when on charge. I mostly drive around my local area 10 miles or so at a time. The battery is dated 2018 if memory serves me correctly. Battery terminals are clean, sprayed with Deoxit and I cleaned the inside of the connectors with 240 grit a while back. It starts fine every time but it does have an occasional mysterious "crunch" sound from the starter particularly when warm. It has a mini starter designed for a Ram truck 360. Thanks for your thoughts and observations.
rags
Senior Member
if you have a good volt meter, check the voltage at the battery with the engine running. if you don't have a decent voltmeter then you should get one. @halifaxhops has been selling some excellent commercial grade equipment.
Thanks for replying. With a digital ohmmeter set at 200 (lowest setting) I get a reading of 0.5 or 0.4 between the battery negative terminal and the case of the regulator. What does that tell me? Is there a poor connection that I need to try and locate or is the regulator bad or maybe both?
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Thank you for replying. The voltage across the battery terminals is within 0.1 of the digital voltmeter plugged into the cigarette lighter socket with the engine running or not.
Sixpactogo
Well-Known Member
.5 is 1/2 of an ohm. It really don't get much better than that. My meter reads .2 across the leads. You have a good ground. If your voltage is above 14.4, you have something else going on. Bad connections, bad regulator.....something.
I'm trying not to waste money on a regulator if that's not the issue. Overall the car is remarkably free of obvious corrosion in the wiring and connections but it is 52 years old. I agree that the high voltages I'm seeing when the car is running aren't good. Thanks again for responding.
I've checked everything that is readily accessible and can't find any poor connections or bad grounds. Has anyone done business with Alternatorparts.com? They have an adjustable voltage regulator that they say is compatible with the 2 field squareback alternator that is on my Fury. Thanks for any input in advance.
I ordered a Mopar Performance Voltage Regulator from Summit. I sanded the firewall to bare metal by the mounting bolts and the back of the ears on the regulator. The triangular plastic shroud around the connectors needed a little shaving inside as it had extra material preventing the plug from inserting correctly. Once it was all installed I fired up the engine and now it maxes out at 14.4v immediately after start up and settled down to about 13.8-14 once warmed up. None of the relevant wires or connectors seemed to get hot and the ballast resistor is cooler to the touch when idling. I'm pretty sure I found the issue and corrected it.
Sixpactogo
Well-Known Member
I think we can say Success!
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