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Ammeter Charging Issue Help

P panterapattMember

All:  Went out today to drive the car this morning.  Up until today, there have been no issues with the car.  Starts, charges, all normal.  Battery is on a BatteryTender at all times when not driving.  Last time car was driven was the day before.   Car starts and warms up fine.   I immediately notice once RPMs get about 2500, the ammeter is on full charge (+ 80 amp side of gauge).  Note, I have a VDO ammeter that I installed many years ago in place of the original meter that Lance Nist had installed his shunt on years before.  When the car is at idle RPMs, the ammeter is reading a slight charging + side like it normally does (BUT, seems higher than normal).  When I apply load to the system - headlights, windows, you see a discharge on the meter as normal.  My fans are wired directly off the battery and turned on, the ammeter does not respond.  I drove the car for about 15 minutes - the ammeter continues to show full charge when at running RPMs and drops to a very low charge at idle.

What I have checked:

1.  Primary lead wires to the ammeter - solidly connected and tight

2.  Battery terminals - clean and tight.  Battery disconnect switch tight.

3.  With car not running, battery shows 12.6 - 12.7 volts.  Car turns over fast as always and does it many times over and over.  Battery water is topped off

4.  With car running on fast idle, alternator shows charging voltage of around 13.6 volts, so system is charging.  

5.  Chassis ground is tight and clean.

What I have not checked:

1.  The battery with a load tester

2.  The terminals at the alternator



So, what do you think could be causing this?

1.  The ammeter is bad and reading excessively now?

2.  The battery is bad, but somehow continues to start the car?



Appreciate the electrical insight and help.  



Lee

Original Post

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P panterapattMember

The ammeter draw is happening when the fans are turned off.  I have two Scotts fans running through 40 amp individual relays.  They are fine.  I see NO draw when I turn the fans on.  Prior to this "event", when I kicked the fans on, the ammeter would surge + for a few seconds and then settle back down to a negligible + value.  

I am thinking the ammeter went bad?

P panterapattMember

Update:  I measured the battery voltage this morning.  11.6V.  Car started, rather slowly, but turned over.  Voltage at idle was 12.0 v; at about 1500 RPM 13.2 v; and at about 2500 RPMs (which maxed the ammeter at 80+ amps), 13.6 v.

So I would conclude the alternator is doing its job as is the voltage regulator and the battery is bad?  

thoughts?

marlinjackmarlinjackThe Machinist #5723 AMARGOSA MACHINE 'Running on Empty- Middle of Nowhere'

...How Many years on the Battery? As You Suspect, sounds like the Battery is going Bad, 'Shorting' Inside. Has the Battery ever been allowed to go 'Dead'? When this happens, the Battery starts to 'Eat' Itself, Up. Destroying itself. Even if the Battery is Not Very Old. The 80+ Amps could be the Voltage Regulator 'Trying' to Charge a Battery that Can Not 'Take', and 'Hold' a Charge. What Happens when the Headlights are turned On HIGH Beam, while Idling? They Should Be White!

I don't think it's the Amp Gauge. Could be the Regulator. Perhaps test the Battery in another vehicle. If You suspect Voltage Regulator, Your Chance to change-over to a Alternator with a Internal Regulator.

The Automobile Battery Must do 3 Things.

Take a FULL Charge.

Hold a FULL Charge.

Deliver Maximum Volts at Amps, Current  On Demand...for 3 to 5 Seconds! Any Longer and you're Burning Up The Starter Motor.

That's All I Have. Good Luck.

MJ

P panterapattMember

Did further investigation with my multi-meter and test light.  Determined something is draining battery.  Started at the Voltage Regulator.  By disconnecting it, drain stopped.  

Looks like a bad VR.  Had this once before years ago.  Lance Nist taught me this troubleshooting technique.  

Alternator is charging.  But if VR is shorted, clearly not gonna work.  Will replace VR and report back.



Lee

P panterapattMember

Replaced the VR which solved the short but the ammeter was still pegged.  Battery could not hold 12.3V.  Got a new battery, resolved issue.  Checked Alternator output which is 14.6 V running fast idle.  Battery voltage not running 12.7 V.

Ammeter behavior back to normal - shows load, charge and quickly returns to neutral with little load on it.

If I had to "guess", the battery (which is over 4 years old) had a bad cell which ultimately screwed the VR.  

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