Wine has a resistance of 74K ohms to 84K ohms.

I am trying to learn how a battery powered PH meter works?

I have 4 different home made red wines, a total of 18 gallons and 11 more gallons to make. Ph paper is not accurate to .1 measurements. It is hard to read 1/2 Ph with ph paper.

People on the wine forum say, buy a good $50 Ph meter. People that have already bought ph meters say, $10, $20, $30, ph meters don't work. Some people with $60 meters claim $60 ph meters don't work.

I assume a ph meter tests the ohm resistance of the acid in the wine. Factory wine is usually 3ph to 4 ph. I made a 1" gap with 2 wires then tested tap water and 2 different factory made wines and 1 of my home made wines.

City water = 96K ohms
The Cab wine = 83.6K ohms ph paper red
The Dark wine = 74.6K ohms ph paper less red

As you can see ph paper is very hard to read. I can barely see the difference in the 2 red ph paper ends.

People on the wine forum don't know about electricity. Does anyone here make wine?

I don't have a digital meter or old needle meter to show ohms for 1" gap wire but I don't need one. I like the flavor of the 74.6K ohm wine best, I think I can add citric acid to wine to get 74.6K ohms. Wine will not be ready to bottle for 6 months nothing to do but wait.

I think I am on the right track. What do you think?

Does anyone know how a battery ph meter works?

I did a search for ph meter circuits and found none.

It's not resistance, its a form of chemical reactivity.
pH meters use something similar to a "battery" effect, with special electrodes to produce a voltage proportional to pH.

Classic style:


Combined style:

A simple unity gain amplifier is all you need and 68mv/pH unit using a decent pH probe. The glass membrane on the probes must never dry out and you need a 4pH and 10pH buffer solution to calibrate on a regular basis (every 10-15 minutes if you're worried about 0.1 unit accuracy. Spend your money on the electrode (probe), the electronics are easy - especially if you already have a DMM and you only need a high input impedance unity gain amplifier (historically, TL082 op amps were commonly used to teach engineers and scientists how to build laboratory electronics.

rjenkinsgb said:

It's not resistance, its a form of chemical reactivity.
pH meters use something similar to a "battery" effect, with special electrodes to produce a voltage proportional to pH.

Classic style:


Combined style:
View attachment 142528

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The ph testers I see for sale have 1 or 2 metal probes. Stick probes in the wine to get a reading. Some testers have 2 metal pins on the bottom that go into the wine. It is hard to tell how the single probe works. One ph meter says the unit needs to be calibrated with a special ph liquid each time it is used. Most testers say, no calibration. How is it possible to know which ph tester works, and which is best? Ebay has a dozen ph testers with pictures but can't tell much from pictures. I need to ask people with ph meter that works, what is, name and model number.

gary350 said:

The ph testers I see for sale have 1 or 2 metal probes. Stick probes in the wine to get a reading. Some testers have 2 metal pins on the bottom that go into the wine. It is hard to tell how the single probe works. One ph meter says the unit needs to be calibrated with a special ph liquid each time it is used. Most testers say, no calibration. How is it possible to know which ph tester works, and which is best? Ebay has a dozen ph testers with pictures but can't tell much from pictures. I need to ask people with ph meter that works, what is, name and model number.

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How will someone confirm that their pH meter works unless they can confirm it gives the same answer as another pH meter? And that both meters aren't wrong (to your required 0.1 unit accuracy)? Note, the reference buffers will cost more than the meters you are looking at. https://www.traceable.com/traceable-ph-buffer-standards.html

ZipZapOuch said:

How will someone confirm that their pH meter works unless they can confirm it gives the same answer as another pH meter? And that both meters aren't wrong (to your required 0.1 unit accuracy)? Note, the reference buffers will cost more than the meters you are looking at. https://www.traceable.com/traceable-ph-buffer-standards.html

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Someone said they bought Pen-PH838 from Amazon. It comes with calibration solution. No manufacture name? Can't find this on Ebay or anywhere else. No information how to use the ph pen. No information about batteries. I hate things with tiny over priced hearing aid batteries that go dead quick. I hate unanswered questions. I hate things with 100s of options and you need to take a class at MIT to learn how to use it. I like, make it simple & make it work.

A lot of cheap so-called pH meters just use two different metal electrodes to give a "battery" effect, rather than having a true (and expensive) pH electrode setup.

As far as I'm aware you cannot get a true pH reading without the proper liquid + membrane electrodes?

rjenkinsgb said:

As far as I'm aware you cannot get a true pH reading without the proper liquid + membrane electrodes?

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Is that the same as you can't get good, long life store brand batteries from a dollar store?

gary350 said:

Someone said they bought Pen-PH838 from Amazon. It comes with calibration solution. No manufacture name? Can't find this on Ebay or anywhere else. No information how to use the ph pen. No information about batteries. I hate things with tiny over priced hearing aid batteries that go dead quick. I hate unanswered questions. I hate things with 100s of options and you need to take a class at MIT to learn how to use it. I like, make it simple & make it work.

Amazon.com : Digital ph tester PEN-PH838

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Then you need a different hobby or you need to worry about different aspects of your hobby than measuring pH to 0.1 unit accuracy.

How will you keep your CO2-filled breath away from your sample (you can change the pH significantly with just your breath when there is no buffer). How did you specify 0.1 unit of accuracy?

rjenkinsgb said:

A lot of cheap so-called pH meters just use two different metal electrodes to give a "battery" effect, rather than having a true (and expensive) pH electrode setup.

As far as I'm aware you cannot get a true pH reading without the proper liquid + membrane electrodes?

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I'm not sure a battery effect is possible on a single, homogeneously mixed container of liquid with electrodes in the same liquid. At that point, you're only measuring conductivity, and by extension, total dissolved (ionized) salts and acids, or electrolyte level. You can only calibrate to pH if there are no other dissolved salts present.

gary350 said:

The ph testers I see for sale have 1 or 2 metal probes. Stick probes in the wine to get a reading. Some testers have 2 metal pins on the bottom that go into the wine. It is hard to tell how the single probe works. One ph meter says the unit needs to be calibrated with a special ph liquid each time it is used. Most testers say, no calibration. How is it possible to know which ph tester works, and which is best? Ebay has a dozen ph testers with pictures but can't tell much from pictures. I need to ask people with ph meter that works, what is, name and model number.

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It's quite simple, don't buy crap off Ebay!

ZipZapOuch said:

I'm not sure a battery effect is possible on a single, homogeneously mixed container of liquid with electrodes in the same liquid.

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That's the most basic, crude primary cell demonstration!
Different metal electrodes in a suitable liquid or stuck in such as a lemon...

rjenkinsgb said:

A lot of cheap so-called pH meters just use two different metal electrodes to give a "battery" effect, rather than having a true (and expensive) pH electrode setup.

As far as I'm aware you cannot get a true pH reading without the proper liquid + membrane electrodes?

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Look at the date on dollars store batteries they are all 2 years old my volt meter shows voltage is low. No wonder they are dollar store batteries they are 2 years old. I never buy dollar store batteries anymore. I only have rechargeable batteries.

gary350 said:

I never buy dollar store batteries anymore. I only have rechargeable batteries

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From the dollar store?

rjenkinsgb said:

That's the most basic, crude primary cell demonstration!
Different metal electrodes in a suitable liquid or stuck in such as a lemon...

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Well, that's a battery effect but I don't know how that will measure pH. And the pH will quickly drop with zinc as the sacrificial electrode and hydrogen evolving from the copper surface as the hydrogen ions collect an electron. I hope he's not drinking the wine with the zinc ions in it.

The voltage will be constant and the current flow will be a function of agitation, acid concentration and surface area of the electrodes (micro etched surface area (not just circumference x length)). Good luck correlating to a pH.

ZipZapOuch said:

Good luck correlating to a pH.

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Exactly.
That's why I said "So-called pH meters" when I said they use that effect!

And in the same post:

rjenkinsgb said:

As far as I'm aware you cannot get a true pH reading without the proper liquid + membrane electrodes?

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rjenkinsgb said:

That's why I said "So-called pH meters"

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Yep, you called them that.

Your ohms meter was simply measuring the impurities in the tap water the grapes drank.
Don't grapes that are not ripe yet have acid in them? Then ripe grapes have the same amount of acid but have more sugar?

audioguru said:

Your ohms meter was simply measuring the impurities in the tap water the grapes drank.
Don't grapes that are not ripe yet have acid in them? Then ripe grapes have the same amount of acid but have more sugar?

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I measured city tap water first it is 96K ohms. Acid in wine is more conductive, it lowers the resistance.

The Cab wine = 83.6K ohms.
The Dark wine = 74.6K ohms.

gary350 said:

Acid in wine is more conductive, it lowers the resistance

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It's not acids specifically - it's any ions in the liquid that improve conductivity.

Try the meter probes in water with salt, for example!

(That's why pure "deionised" water does not conduct).