Correct generator gauge

[ZGjethro]

wrote:
>
I have had my 1952 M37 for a little over a year now, and I have replaced several gauges and sending units. The only non-functioning gauge is my generator gauge. The one in the truck has a center line and a "DIS" on the left and "CHG" on the right. The needle stays right in the middle and never moves. Is this the correct gauge or is the one that says "Battery generator" with the curved color blocks the right one? I have the original style generator and a newer solid state voltage regulator. I am shopping for a replacement and need to know what to buy. Will either style work? Thanks. John

[Lifer]

wrote:
>
The one you have is correct for your truck. (The colored bars were developed for the "HS dropouts" who couldn't understand what dis and chg mean. )

[ZGjethro]

wrote:
> Thanks lifer. I'll start shopping for the original style. Will the other one (colored bars) work with the same connectors if I cannot find the original style?

[MSeriesRebuild]

wrote:
> Thanks lifer. I'll start shopping for the original style. Will the other one (colored bars) work with the same connectors if I cannot find the original style?

Actually either gauge is considered correct with the volt meter simply the later style. If it never moves from center; it isn't working. That could be a result of the gauge being bad, wiring bad, or a charging system problem. Are the batteries staying up? All it takes to hook up a volt meter is 1 hot wire that is charged when the ignition is turned on.

[ZGjethro]

wrote:
> Thanks for the info Charles. I am close to eliminating my final electrical gremlin. I just removed the 12v tap that ran the 12v fuel pump and installed a new 24v pump tonight. I also deleted the 12v running lights the previous fire dept had installed. These taps had messed with my batteries, and I hope they are not shot. I have a new solid state regulator putting out 28.5 v. My old mechanical regulator worked fine though. Should I be able to test if the gauge is bad by putting my meter on the gauge connector and checking for voltage? Would I be looking for 24 from the battery or 28.5 volts from the generator?

I am going to keep the 12v siren the fire dept put on, since it is pretty cool. When I run it all the dogs in the neighborhood start howling! The very intermittent usage will have no affect on my batteries or charging system.

Another question. Do 12v batteries in series (24v) have the same life as batteries in modern cars, and would any battery manufacturer warrantee a 12v battery properly wired in series with another battery?

[8543bob]

wrote:
>
GOOD MORNING, I M PRETTY SURE YOU HAVE AN AMP GAUGE, NOT A VOTMETER. I, PERSONALLY WOULD RATHER THE AMP OVER THE VOLT. JUST MY THOUGHTS. IF IT STAYS IN THE MIDDLE WHILE STARTING OR RIGHT AFTER STARTING YOUR GEN/VOLTAGE REG IS NOT FUNCTIONING OR THE GUAGE IS BROKE OR ITS WIRED WRONG. PUT A MULTI METER ON THE BATTERIES AFTER YOU START AND SEE WHAT THE READING IS ADD A COUPLE OF REVS AND SEE WHAT HAPPENS. YOU SHOULD SHOW AN INCREASE IN VOLTS AS THE REVS INCREASE; TO A POINT. GOOD LUCK BOB

[ZGjethro]

wrote:
>
Bob, are the gauges I described amp gauges or volt gauges. I read somewhere that generator equipped trucks have amp gauges and alternator trucks have voltmeters. Is this true?

[Glenn]

wrote:
> The one you described being in your truck sounds like the ammeter, the colored bars would be the volt gauge. Personally I feel you get more immediate information about your charging system and it is easier (to me) to tell how much current is being drawn with an amp gauge.

[Lifer]

wrote:
>
The ammeter (- | +) tells you what your generator/battery is doing. If it's in the + range, the generator is charging the battery. If it's between the + and the -, the battery is neither charging nor discharging, indicating a full charge. If it's in the - range, your electrical system is drawing more current than the generator can keep up with. This means either your system is overloaded, your generator needs attention, your voltage regulator needs attention, or your batteries will not take a full charge. Pay attention to this guage!


The voltmeter operates differently. It tells you what condition your batteries are in. In the green means your batteries have a full charge. In the yellow means that you have less than a full charge, and in the red means that your batteries are very weak. You should pay attention to this guage, too! If it's in the yellow when you first start the engine and you run it for a while, the needle should move into the green if the generator is putting out. If it dips into the red after a while, your generator isn't p[utting out enough current.

There are pros and cons for either guage. I prefer knowing what the charging system is doing (the ammeter), but the ability to grab a quick glance at the "color chart" and see what condition the batteries are in is handy, too. (Having both would be good. )

[ZGjethro]

wrote:
> I just ordered the colored gauge yesterday. If it is a volt meter and my charge/discharge gauge is an ammeter I might have ordered the wrong thing. I might keep it and try to order an ammeter. Both would be nice, and a voltmeter would be easy to wire in.

[cuz]

cuz wrote:
> Amp meter shows rate of charge or discharge. It offers no other accurate
> electrical system performance data. It was the basic gage introduced for
> common use by experienced and inexperienced drivers. If you note the
> published repair and adjustment data you'll note that volt readings and ohm
> readings are the primary measurements taken to insure correct system
> performance. Next came the idiot lite. The amp meter gets it's information
> thru wires #8 & #9 from a remote shunt located inside the mechanical
> voltage regulator.
>
> The military voltmeter provides a more direct voltage related reading but
> does not offer an accurate number value.
>
> The Army went to the volt meter when the later transistorized voltage
> regulator came on line. The primary reason for this is that the
> transistorized voltage regulator does not have a shunt in it for an amp
> meter. Therefore the #8 & @9 wires have nothing to connect to.
>
> Since you have an amp meter and a more modern transistorized regulator your
> amp gage has no information available to it. Therefor the needle does not
> move.
>
> When you get your new colored range marked generator condition gage (volt
> meter) it will usually only have one Packard connector which you will need
> to connect to the #27 wire spider or an extra wire off your main switch.
> Leave #8 & #9 disconnected and taped over. Be sure if you use an extra
> wire off your main (ignition) switch that it is hot only when the switch is
> on or you will run down your batteries regularly.

[ZGjethro]

wrote:
> Thanks Cuz. That was the answer I was looking for. The ammeter was not working before I changed to the transistorized voltage regulator a few weeks ago. I am glad to hear that the gauge I bought will be the one I need.

[ZGjethro]

wrote:
>
The new voltmeter gauge is installed and working! When the truck is running the needle is in the top third of the green. When the ignition is on but the truck is not running, the gauge is centered between the green and yellow. This was the last gauge which I needed to replace and now everything on my dash works. Thanks for all the advice

[M37UK]

wrote:
>
The new voltmeter gauge is installed and working! When the truck is running the needle is in the top third of the green. When the ignition is on but the truck is not running, the gauge is centered between the green and yellow. This was the last gauge which I needed to replace and now everything on my dash works. Thanks for all the advice

Its a good feeling, isnt it !!

[Lifer]

I'm glad you got your new guage and that it works! Beats the heck out of wondering, doesn't it?