g741.org

wrote:
>
It is great seeing all gauges working. My batteries may not be the best since I had a 12v tap running a fuel pump until recently, so I am not sure how they should register. With the ignition on but the truck not running the needle is centered between the yellow and green. My multimeter is at work now, or I'd measure my battery voltage. Running the needle is in the upper green. The change of the needle shows the higher charging voltage, which tells me the gen and regulator are doing their job. It would be nice to have an ammeter though. I work as an electrician, and we use a clamp on amp meter. They are basically a coil around the wire being monitored. Are there similar items which would sense current flow without being wired in series? Is it possible to have a current transformer operate a gauge?

wrote:
> wrote:
> > KG. Is this what your looking for
> >> http://www.summitracing.com/parts/ATM-6390/
> > It appears to be an amprobe type meter. But as you can see its a little
> > costly. I have the color coded voltmeter in my truck. But I would like to
> > monitor my electrical system more closely, that's why I was going to
> > install a digital voltmeter in the glove box of my truck this spring.
> >
> > Sal
> >

wrote:
>You can add an amp meter along with an external shunt in the #4 wire circuit. The voltmeter offers a lot more information then an amp meter will give you about your truck's electrical system. If you want a little more accuracy on your color coded volt meter just parallel in your digital VOM and mark actual numeric volt readings on the gage as you vary the condition/charge rate of the truck and battery.

cuz wrote:wrote:
The voltmeter offers a lot more information then an amp meter will give you about your truck's electrical system.

Not really, Cuz. Both give you a lot of information...just about different things.

The voltmeter tells how much of a charge is in the battery or batteries. High green indicates a full charge, low red indicates dead. If the needle starts heading toward the red, you are losing the charge in your batteries.

The ammeter tells what the generator is doing. High + indicates that the generator is pumping juice into the battery as fast as it will go. The charge rate gets lower as the charge builds in the battery until it gets to the middle and stops. If you have the lights on without running the engine, it will show a discharge. Same goes when the engine is running if your systems are drawing more current than the generator can supply.

With fully charged batteries, the ammeter will "hover" around the mid-point, occasionally showing a bit of a charge as engine speed increases (zipping downhill?) or dipping into the discharge area as engine speed decreases (lugging down on an uphill grade?). These conditions are normal and what I like to see. I think "idiot lights" are the worst thing car makers ever came up with. By the time they come on, the damage is usually done. They would have been better off to teach people how to read guages! (Just sayin'.)

wrote:
> Thanks for the link Sal. I bet that is a 12v unit though. I like how it is non-invasive. Now I need to find a 24v model

wrote:
> I have to disagree. The volt meter is hands down the greater provider of info and the most useful condition gage of the two..

The six tasks you described for your amp meter are all the same task! Current flow! For an amp meter to indicate above the zero the generator's voltage output has to be higher than the voltage of the battery with all system load's. The volt meter tells you this. I am not happy with the military volt meter's lack of markings which can easily be added to the glass.

1-The ammeter tells what the generator is doing. which way the current is flowing.
2-High + indicates that the generator is pumping juice into the battery as fast as it will go. High current flow +
3-The charge rate gets lower as the charge builds in the battery until it gets to the middle and stops. Tapering current flow and then stabilized balanced current flow.
4- If you have the lights on without running the engine, it will show a discharge. - current flow
5-Same goes when the engine is running if your systems are drawing more current than the generator can supply. - current flow.
6-With fully charged batteries, the ammeter will "hover" around the mid-point, occasionally showing a bit of a charge as engine speed increases (zipping downhill?) or dipping into the discharge area as engine speed decreases (lugging down on an uphill grade?). + or - current flow.
These conditions are normal and what I like to see. I think "idiot lights" are the worst thing car makers ever came up with. By the time they come on, the damage is usually done. They would have been better off to teach people how to read guages! (Just sayin'.)

1-The volt meter tells what the generator is doing. Upper Green with the engine running equals charging. +current flow
2-Top of the volt meter green indicates generator at full output. Red indicates excessive charging voltage. Hi + current flow
3-Center of green during operation indicates normal charge rate. Balanced or slightly + current flow.
4-If you have the lights on without the engine running the voltmeter will indicate low green or yellow. - current flow
5-Same with engine running and electrical load higher than generator's rating, voltmeter will begin to indicate low green or lower. - or barely + current flow.
6-With fully charged batteries and light loading voltmeter will indicate middle to upper green. Stabilized current flow. And when reducing engine speed slightly down from middle green and when increasing engine speed slightly upper green.

In the case of an alternator equipped truck the voltmeter's middle to high charge rate sensing will be barely discernable since the alternator maintains a much more constant voltage at all loads. Most modern vehicles with gauges actually place the numerical volt values on their gauges.

wrote:
>
Cuz, good idea marking voltages on the voltmeter's lens. If the meter mover to the right, it will indicate charge, since the current will flow from high voltage to lower voltage. What the volt meter will not show is a numerical amount of that charge. For my own curiosity I would like to see the charge rate, without splicing into, or altering the factory wiring.I have spent the last few months elimination electrical gremlins, and everything is working correctly now.

ZGjethro wrote:wrote:
> Thanks for the link Sal. I bet that is a 12v unit though. I like how it is non-invasive. Now I need to find a 24v model

Ammeters are not volt sensitive, the same gauge will perform equally in either a 12 or 24 volt system. The only concern would be to make sure you obtain a meter that has a replaceable light bulb so the proper bulb for your system voltage can be installed. An excellent souce for gauges is DATCON.

ZGjethro wrote:wrote:
>
Cuz, good idea marking voltages on the voltmeter's lens. If the meter mover to the right, it will indicate charge, since the current will flow from high voltage to lower voltage. What the volt meter will not show is a numerical amount of that charge. For my own curiosity I would like to see the charge rate, without splicing into, or altering the factory wiring.I have spent the last few months elimination electrical gremlins, and everything is working correctly now.

Datcon voltmeters are readily available with number markings for both 12 or24 volt systems. They are a product of Maxima Technologies. We use their gauges frequently in our rebuilt trucks, results have been positive.

wrote:
>
Thanks for the explanation of the volt meter, Cuz. I thought that all they indicated was the state of charge in the batteries. The VOM seems to be more useful than I thought. Once again, an "olde pharte" has learned something.

wrote:
> I have ammeters in my 3 Willys Jeeps, I agree on the idiot lights.....horrible idea. I have always had full confidence in knowing what the charging systems are doing. The voltage regulator stuck on my Willys wagon and as soon as I shut if off I noticed the ammeter discharge side pegged! Of course next I quickly opened the hood and found a hot to the touch wire. Correct me if I'm wrong but I don't believe I would have noticed it instantly with a voltmeter. I do agree the voltmeter shows more information, but does it instantly show a current draw such as one from a stuck regulator?

MSeriesRebuild wrote:

ZGjethro wrote:wrote:
> Thanks for the link Sal. I bet that is a 12v unit though. I like how it is non-invasive. Now I need to find a 24v model

Ammeters are not volt sensitive, the same gauge will perform equally in either a 12 or 24 volt system. The only concern would be to make sure you obtain a meter that has a replaceable light bulb so the proper bulb for your system voltage can be installed. An excellent souce for gauges is DATCON.

Charles, I was thinking of a powered gauge like the one Sal posted http://www.summitracing.com/parts/ATM-6390/ but I will look into the Datcon models, especially if they are more original looking.

Correct me if I'm wrong but I don't believe I would have noticed it instantly with a voltmeter. I do agree the voltmeter shows more information, but does it instantly show a current draw such as one from a stuck regulator?

The voltmeter would have shown a sudden decrease in voltage due to load but the needle swing would not have been as far as the amp meter. You would have noticed it fairly quick without any gauges. When the Circuit breaker (cutout relay in some regulators) sticks closed and the engine is not running the battery then will try to run the generator like an electric motor. If the belt has a little slack you will quickly smell the belt rubber burning and if the belt is real tight you will quickly smell the battery cable burning.

Although commercially available amp meters are not voltage sensitive they come in several types. There is the direct reading amp meter found in many older vehicles and all the actual current loads pass right through it. Then there are the remote reading amp meters which use an external shunt and the actual current loads run across the shunt. These shunts usually come in several amperage ranges so you must select the shunt that best matches your system amperage rating.

If you are using the transistor voltage regulator then the military amp meter will not function. The military voltmeter is the next best match for your other gauges. It is a very simple procedure to calibrate it and mark the numerical values on the lens using a digital VOM as a reference. If you query the instrument repair shops you can come up with vinyl or decal gauge range and marking kits.

ZG. Being a LED read out gauge it would need voltage to operate it. But nowhere in the AD does it give the operating voltage. You can also look into Marine Supply's. There is a lot of boats that run off of a 24 volt systems.

Sal

So I took the truck to work today and drove home in the dark. The new gen gauge (colored bars) does not let any of the red dash light onto the gauge face. Is this correct. The Gen gauge is the only one that is unreadable in the dark.