mgbrewer

I recently bought a '67 427/400. The battery has a full charge and works well. My battery gauge rests in the middle of the dial when idling but the needle goes all the way to the right (+40) as I accelerate and drive the car and even though the battery is fully charged the needle only goes back to middle only at idle. Is this normal to have the needle at +40 with a fully charged battery when cruising? - Mike

JohnZ

No, it's not - your voltage regulator has failed, and it's going to cook your battery.

mgbrewer

That was my first thought so I replaced it with a new new one and the problem still exists.

babbah

Perhaps your gauge is "going south". Try another gauge and observe the readings then go from there. These devices are very sensitive for sure and do go bad.

Nowhere Man

Check your wiring. I had a new solid state VR once and it over charged too. Swapped it for a original points one and problem solved.

Vetterodder

My `65 began overcharging. By the time I found the problem it'd ruined the battery and the alternator. Turns out there was a break in the ground lead to the regulator which forces the alternator to max out. An easy test is to run a jumper from the regulator ground terminal to the frame or engine. If charging returns to normal you found the problem.

plaidside

Vetterodder is correct to try the jumper from regulator base to engine ground.
Did you connect a voltmeter to the battery and check to see if the system is overcharging above idle?
It should not go above 14.5v.
Joe

RatDog

I use one of these gadgets. It reports the condition of the battery when the engine is off and shows how the alternator is functioning when the engine is running:


-- Steve

mgbrewer

I put a voltammeter on the battery at rest 12.0 and got 12.75 at idle and 14.7 past idle is the highest I get. Is it fair to assume that my gauge is either too sensitive or not reading correctly?

babbah

The voltages you are reading seem to indicate that your battery may be the culprit. When the battery is fully charged at idle the reading should be around 13.8vdc.
Unless your battery was down a bit when you metered it above - these readings could be normal but at idle if it was low the gauge needle should be more to the right (Charging)
If you are absolutely sure your battery is good then: **Note that a fully charged battery when car is shut off should read around 12.5v. (Mine reads 12.75v)
I'd also check for a parasitic drain on the battery when the car if off. Disconnect the neg terminal on the battery and then measure the voltage of it to see if its at 12.5v. If it isn't the battery could be the issue and the charging system and the gauge are working normally.
If you think your battery is good then:

You need to:
1. Replace the gauge and observe readings - You can simply pull the 2 wire connector off the back of the battery gauge on back of dashboard and feed it down to another gauge. 5 minute job. if same then:

2. You could have a high resistance connection on one or both of the 12v feeds to the gauge itself. (The 2 wires on the back of the gauge)
Remember the gauge is actually not a ammeter but a galvanometer that measures the 12vdc differential voltage between the battery and the horn relay.

The feeds to the gauge originate from:
A: The horn relay positive term at the front drivers side of the radiator
B: The starter solenoid 12v Battery terminal

Both of these feeds include fuse links - these need to be checked as well.
** CHECK THIS OUT NOW!! - These connections run to the gauge via the 2 bulk head connectors on the firewall - in front firewall side of the fuse block:
Check the bulk head connectors located under the master brake cylinder - there are 2 of them - get your hand on each one and make sure they are both pressed in securely and the tabs on each upper connector are engaged (Locked). This could be your issue as well - a simple fix!! (They are prone to all sorts of electrical issues due to years of corrosion - I'd disconnect each one and see how the pins look and clean them if required and then securely plug them back in.... (DISCONNECT BATTERY BEFORE DOING THIS!!)

3. Try another Solid state VR - I have one and its perfecto!! AutoZone - Wells VR715

Battery Gauge Needle should be Straight up at 0 when battery is fully charged and idling or a tad bit to the right when running normally.

IMO - you issue is either the battery or one of the connections to the gauge itself (circuit).

Good Luck!

mgbrewer

The car has 62 miles since a complete frame off mostly NOS resto. BTW I did not do the resto and for what it is worth the car won a Top Flight award in Oct. My problems began when the starter would only engage occasionally (sometimes wouldn't even click) and it was killing my battery so I sent the starter back to be RE-redone including starter solenoid. I installed a NAPA starter and thought my problems we gone because it was starting properly, every time, but now I know the car is still not charging correctly. (check out my first message) So, after I fried the battery I installed a new one as well as a new VR but the car is still not charging correctly and I'm not very technical and I'm stumped. One Vette shop tells me the charging is correct but look at my numbers it isn't right. I REALLY do appreciate all the assistance you guys are providing.

Sky65

Where does the amp needle sit when the key is off?

mgbrewer

in the middle

Sky65

OK. Just a weird thought that maybe someone changed the gauge to a voltmeter and left the amp face on it. If it was pegged to the left with the key off, center scale when idling and full scale above idle it would be a possibility. Oh well. Just a thought.

Tom

VetteRed1965

This happened to me ...

Wayne1964

I had the same problem replaced the gauge . Is the altinator pully correct dia. ?
Volt meter will tell you if it is charging or not. Also check Battery terminals are tight.
I found my clock would kill the battery . I use a battery tender now. good luck

DansYellow66

I have had lots of charging problems related to voltage regulators - unfortunately they have all been with a Mopar and a Ford. But in both cases the system voltage was reading low 12.5+/- and not high. The Mopar ended up having a bad voltage regulator and 12.5V was about all it would do which is not enough to charge a battery. The Ford had a charge indicator circuit and red ignition light that is supposed to "excite" the VR to start regulating. I had to install a resistor in the system in parallel to generate enough signal to get the VR to start up. Again, I could not get more than about 12.5V anywhere in the system - my point is that in my experience alternators default to battery voltage (12.5 V) in the absence of a signal from a VR.

My suspicion - and I will qualify it by saying that I'm not a strong electrical person and hate electrical issues - would be that your alternator may be faulty. I think I would take it down and have it bench tested at an auto parts store.

54greg

rongold

According to the Interstate battery manual, a fully charged battery should read 12.7 to 12.77 volts with no load. 12.2 volts with no load represents a battery that is only 20% charged. I think your battery is either NOT fully charged or defective. If it's not fully charged, then what you are seeing on your ammeter is perfectly normal. Being that your maximum charging voltage is 14.7, I would say that your voltage regulator is OK, but your battery is not fully charged.

mgbrewer

Problem solved. Loose alternator ground and battery not fully charged. Thanks to all. Mike