Use Local Voltage To Sense Remore Voltage (Meter)

[MEXICOWANDERER]

http://www.buyincoins.com/item/26013.html#.V0yNGeSG9_k

This link takes you to an accurate digital voltmeter. One of the problems with using a remote mounted meter, is that it reports what it see's, no matter how severe the voltage drop. This meter uses local power to light the LED segments, and remote sensing to read power AT THE BATTERIES. Or panels (to 33 vdc) or converter, or inverter input, alternator output stud, ignition feed, or whatever you wish to monitor.

This critter makes an utter laughingstock out of the "accuracy" of 3-1/2 digit voltmeters.

Sure it's expensive - way beyond the reach of most of us. But when money is no object...

[Harvey51]

I have never seen a voltmeter that needed a 12 volt power supply. Don't they all use internal 9 volt batteries now? My UNI-T multimeter says it has a 10 Megohm input impedance on all ranges so the current drawn could not be more than I = V/R = 12/10^7 = 1.2 micro amps. Voltage loss in a 1 ohm wire would be V=IR = 1.2 * 10^-6 = 1.2 micro volts. Looks to me like it would take a 100 ohm wire to change the hundredths of volts on the reading.

[MEXICOWANDERER]

Process of elimination. DISCARD the far right digit altogether. It is a + - error trash can. The 2nd from the right digit can likewise be ignored - to a degree.

Buy a can of KRYLON paint ESPECALLY for plastic if you wish. BLACK works well.

Obliterate the fifth and fourth least significant digit if you must.

I have two of these meters for bench testing. They are accurate enough to be useful.

My postings of these types of goodies is not to be construed as "arm-twisting". Merely availability and perhaps good value. When I was 14 and riding fence in Montana, the line shacks had kerosene lamps and I did not have so much as a flashlight. A canvas army cot with fruit crate "foot extender" served as a bed.

I obviously believe in "Do-It-Myself" projects.

An out-of-the-box-guaranteed-accurate 3-1/2 digit LED voltmeter costs $200+ dollars. Why bother? A five-dollar meter with the two right hand most digits blocked off is just as accurate.

Parading voltage droop or incline can be a powerful trends-and-tendencies tool.

And for calibrating, only a verified accurate oscilloscope is proof-positive of accuracy of values. Over the years I have uncovered FLUKE meters that were so far out of kilter, they were a joke. My .001% accuracy decade resistor verifier is in Michoacan. Between the Tektronix and resistance verification, measurement instruments can be tested. Otherwise determining accuracy is hunch guesswork.

[landyacht318]

How is it known this meter is indeed accurate? They do not seem to have a calibration pot.

I've had more than one voltmeter well out of line with true voltage.

I'd enjoy voltage to the 0.01v on some of the displays I do have, but 0.1v has been revealing enough. I think the flickering of the second digit might become annoying.

[SCVJeff]

smkettner wrote:
One digit is enough to tell me what is happening.

.5 ? :C

[time2roll]

One digit is enough to tell me what is happening.

[2oldman]

I'm sorry.. what's expensive?

[MEXICOWANDERER]

"Is this April Fool's day?"

Only if your name is April

Here is perhaps a clarifying example

Voltage meter
A heavily loaded circuit is tapped as a power supply for the meter because the wires to tap into are "convenient"

The meter is read believing the value to be accurate, actually when enduring a .2 - .5 volt drop because of the load.

2nd device advantage
A meter needs TWELVE VOLTS to operate
This meter when connected across a circuit read AGAIN A-C-R-O-S-S a circuit can read voltage drop.

Wanna get fancy, use a gold flashed rotary switch and monitor voltage drop from three, four, eight places. Like ACROSS a PWM or MPPT controller (33 volts max)

Using telephone line wire can be fished where eighteen or twenty gage would have problems.

I would not use a loop powered voltmeter.

About sixty years ago on Armed Forces Day, I toured a Fleet Class US submarine at Mare Island with my dad. I got as far as the maneuvering room. A NCO showed me the analog instrumentation used for both battery banks. My father had to physically pry me away from the station. The entire crew including the XO were having belly laughs. One Chief hollered "There goes a destined, sure-fire electrician's mate!"

Yup, one of these critters is going on Quicksilver. Jesús, will help wire it into the panels, C60 Trace, alternator, and Distribution switch/breaker feed. The Cruising Eqpt Co panel meter is already connected to the L-16's.

I already have the gold contact rotary switch.

Oldfarts gotta have projects...

[CA_Traveler]

But with a major problem since it uses the negative power wire for the remove voltage. So it's not exactly reading the remote source voltage.

Also can't think of any RV or solar related voltage that I need resolution to 1 milli volt.

[MrWizard]

My recently installed meter with the 200 amp shunt
Has remote voltage sense option,
You can wire it to a local power source to power it, and it will sense voltage at the batteries not from the wires powering it

[2oldman]

Is this April Fool's day?