Volt Gauge

[F164]

My 64 F100 has the original generator. The PO removed the wiring for the gen and oil idiot lights and installed gauges in their place.

Tonight I drove the truck after dark and turned the headlights on. I think this is the first time I have ever had the truck out after dark. Anyway, as soon as I turn the headlights on, the volt gauge goes from reading 14v to zero.

Does this mean the gen is not charging?

I have no idea how the gauge was wired, I would have to remove the cluster and start tracing wires to figure it out.

[bruceandersson]

Something is wrong with how the guage is set up if the truck kept running. You can expect the voltage to drop with the lights on but only a volt or two at idle.

[Toyz]

Should be able to pick up a feed for the voltmeter from any "hot" wire, although it sounds as if this may be a problem in the ground circuit. Quite correct that this is probably NOT a charging problem. If a correctly wired voltmeter accurately reads zero, lights and other electrical is not going to continue working.
Paul

[banjopicker66]

I think it would be helpful to ID the type of "voltmeter" you have since they were replaced.

Gauge Type #1 - True Voltmeter: This voltmeter pegs all the way to the left on 0V, and all the way to the right on 18V or 20V (whatever the maximum number is.) It floats somewhere in the middle of about 13V-14V when the charging system is working normally.

Gauge Type #2 - Ammeter: This type of meter can be confusing because some aftermarket kinds are often and incorrectly labelled "Voltmeter." A true Ammeter pointer normally rides in the middle, pointing straight up and down or almost straight up and down when the truck is turned off, and when the charging system is balancing the discharging.

When the truck is turned off AND no current is flowing, the pointer will be straight up and down, showing no charge or discharge.
When the truck is turned off BUT there is current flowing (a hidden device such as an alarm or radio memory keeper) then the pointer will show DISCHARGE.

Does your truck demonstrate anything similar?

[Toyz]

John, I don't believe any ammeter, regardless of any possible mid-labeling, is likely to have a "14v" marking. It would be possible for the voltmeter to be wired in such a way as to indicate voltage at the generator circuit. This setup might indicate 0 charging output at low generator rpm and high load. I can think of no practical reason for that setup; other than for diagnosis of generator output or to measure voltage loss at the points of attachment. Thus, it is more likely some other glitch in the voltmeter circuit.
Paul

[banjopicker66]

John, I don't believe any ammeter, regardless of any possible mid-labeling, is likely to have a "14v" marking.
Paul

Paul, I would expect an ammeter to be able to show 30A in either a charge or discharge condition. My original Ford ammeter does.
As for voltmeters, I would expect them to show a max of 20V. Not sure what the actual maximum output would be, but I know that small-sized ammeters were used up into the 1980s on various vehicles and and brands, but were labeled at the dash as a voltmeter (presumably because Ford/GM/Etc thought the owner was too stupid to know the difference?)

Now I just realized there are 3 variables here.

1. I have a 1966, not a '64.
2. Which, of course, means an alternator, not a generator.
3. Also, I was concerned the aftermarket gauges are throwing me a loop here. I was attempting to ID if the original poster has a true ammeter, or a simpler voltmeter. Are 14V outside the ability of a generator's expectations, especially if trying to rebuild a charge on a weak battery, for example?

Perhaps that is the reason for the disconnect here in my mind?
(Not to mention the physical discomfort is a bit much today? If so I sincerely apologize.)

[Toyz]

John, sorry to hear of the pain! The original post stated the gauge dropped from 14 volt to zero; thus my assumption it is in fact a voltmeter. A healthy generator should be capable of 14 volts, but probably not at low engine speeds. I still am inclined to view this as a wiring problem rather than a charging problem.
Paul

[banjopicker66]

Thanks Paul, just not the best of days.
I think we are in violent agreement here, just looking at it from different angles.

[ICEMAN6166]

when i had the generator a minimum of 500 rpm to keep the light off

now i have a low amp alternator with an ammeter which has no problem reading +30 amps if i have lights,heater fan and wipers on

going to go to a 100 amp 1 wire alt soon , and probably trade my ammeter for a voltmeter to eliminate wire and because the ammeter only goes too 60 amps
with a 100 amp alt i think there could be issues.

going to see if i can order one of thse from work

http://faria-instruments.com/site_manua ... icator.pdf

[Toyz]

Well, we have covered our thoughts as to the source of the problem; might as well attempt to answer your query! The system probably is NOT developing enough amperage to be charging, especially with the load of lights, ignition, etc. at low rpm. As Ice stated, that is just the nature of generators. An easy way to determine what is going on would be with an inexpensive diagnostic multimeter or voltmeter. They can be found for under $10.00. Clamp it on to the battery and check volt output at different rpm, lights on and off. A good generator should charge above 1000 rpm or so; lights on, the gauge is apt to show less than battery voltage due to the draw. If it picks up to 13.8 volts or more as rpm is increased; I'm not sure I would address the voltmeter. Another $10.00 possibility, if you have a cigarette lighter, is the solid state voltmeters which you simply insert in place of the lighter. This will give you continuous assessment of the charging voltage, or lack of same, under driving conditions. I still would be curious how the installed voltmeter is wired, but if it has no effect on anything else; maybe not enough to tear apart the instrument panel.
I might add, in case you consider upgrading to an alternator, Ice and I do differ on the one-wire applications; while they work adequately in most instances; I would as soon run the two additional wires. Even the most penny-pinching manufacturers avoid the potential savings of the simple one-wire; if they are convinced it is not in their best interest, I ain't gonna argue!
Paul

[ICEMAN6166]

not going to argue for or against any system they all have issues from time to time.
we do sell a lot of them 1 wire to farmers for tractors.
all sorts of pulleys too so maybe i can find a newer ford internal regulated one and swap pulleys

couple things to say about low amp alternators and generators
the more old high amp accessories you have the less well they work
LED light use very little power. the more of them you can use the less the generator works
generators do not work very well for winches or plows either.

as with all electrical stuff check grounds

[Toyz]

The Delco's are my preferred choice for farm equipment also. Funny the LED comment should come up; the Facebook forum has a current post from someone with a '64 inquiring about LED headlamps. Another poster is trying to steer him toward halogen headlamps. Even ignoring the output comparisons, I don't consider that a good choice for a '64 with original wiring, especially if equipped with generator. The relay mod will take care of the switch; the generator still may not like the extra load in comparison to the original 6012 headlamps. Just like with the winch example, a good battery can certainly mitigate the situation, but an adequate charging system is a definite help. There is quite a difference in power and brightness between the 12+ volt battery output, and that of an efficient charging system keeping up at 13.8 volts or so.
Paul

[F164]

No brand name on the volt gauge, its an old gauge, maybe 30+ years old.

With the key off the gauge reads zero, if I put the park lights on the gauge bottoms out further to the left.

The battery that was in the truck when I bought it is a deep cycle marine battery, its huge.

Im going to replace both gauges with AutoMeter units in a new gauge pod I have. The pod is made to accept AutoMeter gauges.

On my 66 with an Alt, the idiot light has to function to make the alt charge. Are the Gen equipped trucks similar?

Someday when the Gen gives it up I will go to an Alt but I really don't drive at night so there is a minimal load on the charging system.

I am going to install relays on the headlights.

[ICEMAN6166]

The Delco's are my preferred choice for farm equipment also. Funny the LED comment should come up; the Facebook forum has a current post from someone with a '64 inquiring about LED headlamps. Another poster is trying to steer him toward halogen headlamps. Even ignoring the output comparisons, I don't consider that a good choice for a '64 with original wiring, especially if equipped with generator. The relay mod will take care of the switch; the generator still may not like the extra load in comparison to the original 6012 headlamps. Just like with the winch example, a good battery can certainly mitigate the situation, but an adequate charging system is a definite help. There is quite a difference in power and brightness between the 12+ volt battery output, and that of an efficient charging system keeping up at 13.8 volts or so.
Paul

the halogen headlights with the relays are plenty bright, i even did the step so low and high beams can be on at the same time.

could spend lots of extra $ on these lights, but i was told this one is not a lot brighter than the standard halogen, considering the price

http://www.federalmogulmp.com/en-US/Bra ... ductId=557

these are the LED sealed beams

http://www.federalmogulmp.com/en-US/Bra ... ductId=831

[Toyz]

If originally equipped with the idiot lamp, yes, it is an integral part of the charging circuit. Not sure how your system is currently wired, but it sounds as if it may be sensing generator output since it appears show almost zero when it should be reading actual battery voltage. It is possible that is correct for your gauge; I agree a new gauge would be worthwhile.
Paul