Test meter hates

[John Stevenson 1Participant @johnstevenson1]

[John Stevenson 1Participant @johnstevenson1]

Why does a test meter need batteries when you are measuring a voltage.?

Which roughly translates to the damn battery's are flat but I only want to see what voltage is at the ends of this cable.

OK can understand you need a battery to measure resistance as there usually isn't any voltage / current but if you have a supply of say 48 volts then why can't it just read this and not rely on the last battery in captivity ?????/

[clivelParticipant @clivel]

If it is a regular analogue test meter without any electronic amplification, then there should be no need for batteries except for the resistance ranges. My 40 year old Avo 8 hasn't had batteries for years and still works perfectly, I just don't use it for measuring resistance.

Of course this doesn't apply to digital meters which will require power to run the circuitry.

Clive

[I.M. OUTAHEREParticipant @i-m-outahere]

So you can't use the meter to test it's own batteries !

Ian

[John HaineParticipant @johnhaine32865]

Even on an Avo 8, probably not from the test leads, though IIRC it has a test button which allows you to.

[Boiler BriParticipant @boilerbri]

Your not using it regularly enough to keep on top of the battery life😜.

Bri

[richardandtracyParticipant @richardandtracy]

My ancient analogue one does everything, except resistance testing, without batteries.

Regards,

Richard

[Stuart BridgerParticipant @stuartbridger82290]

My trusted 30 year old digital fluke Fluke 77, I think has had one new battery (PP3) in all that time.. Doesn't get used that often though.

[davebParticipant @daveb17630]

I was working on a BIG hydraulic press, used my brand new Fluke meter to sort out a control fault. Having sorted out the problem, I tested the machine. Anyone interested in a very thin Fluke multimeter?

Daveb

[John Stevenson 1Participant @johnstevenson1]

Posted by daveb on 31/07/2015 10:05:46:

I was working on a BIG hydraulic press, used my brand new Fluke meter to sort out a control fault. Having sorted out the problem, I tested the machine. Anyone interested in a very thin Fluke multimeter?

Daveb

.

So it also needs the thin coin cells now ?

[BazyleParticipant @bazyle]

One of my earliest jobs in paid employment was drilling 3 in holes with a tank cutter in metal boxes for some volt and amp meters for bench test equipment. We moved on to digital meters that got updated every few years until the leads were bigger than the meter and the damn thing would scoot across the bench when you nudged a lead. Meanwhile I liberated one of the 15v plain meters and this morning checked the Landy battery with it. This meter hasn't had a battery change in 40 years.

[modeng2000Participant @modeng2000]

Posted by Stuart Bridger on 31/07/2015 09:14:37:

My trusted 30 year old digital fluke Fluke 77, I think has had one new battery (PP3) in all that time.. Doesn't get used that often though.

I've just replaced the one in mine.

[Ian PParticipant @ianp]

Posted by John Stevenson on 31/07/2015 00:45:28:

Why does a test meter need batteries when you are measuring a voltage.?

John, is that a serious question?

Any meter that does not contain batteries has to get its power from the thing you are measuring therefore it cannot read it without affecting its value.

Even a simple moving coil meter has to draw the power to move the needle from somewhere, circuit diagrams of yore usually specified the Ohms per Volt of the meter that was used when the datasheet values were noted. The displayed voltage is lower than what the circuits operating voltage will be when the meter probe is removed. Modern electronic and even cheap DVMs have a high enough input impedance have all but eliminated the practice.

There are plenty of voltmeters and Ammeters that get their operating supply from the measuring input but they are not general purpose multimeters.

Ian P

[Jesse Hancock 1Participant @jessehancock1]

Interesting that no one is reporting corrosion on terminals after leaving all that time? I must be doing something wrong!

[Neil WyattModerator @neilwyatt]

Simples! Get one with auto-off.

As someone who grew up borrowing dad's AVO8 and having some very nice analogue meters, the accuracy and convenience of digital ones still amazes me.

If you blow up a £10 digital one, you just replace it, my Eagle has evidence of a number of repairs from when my Dad had it.

Neil

Oh, and I do have a digital meter that gets its supply from the circuit under test –  a basic AC supply checker.

Edited By Neil Wyatt on 31/07/2015 15:55:12

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