False salt readings

Because OP has a r1.40 board, he cannot change cell type on display, but I guess he can move the jumper on the board so the cell becomes a t-5. I think OP's main question is if he can bypass the temp sensor and fix the salt reading at a steady 3000ppm because he doesn't want to purchase a new cell. Hopefully he realizes his cell is failing yet again. The short answer is no, bypassing a cell with plates that are wearing out. Upgrading to a new board will allow t-cell type changes that allowed mas985 to extend the life of his cell. But others have gotten much shorter extensions.
 
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Because OP has a r1.40 board, he cannot change cell type on display, but I guess he can move the jumper on the board so the cell becomes a t-5.
That should still work ok. The T-5 is half the size of the T-15 cell so the salt level will approximately double from where it is now.

But as I mentioned in the previous post, you can spoof the the controller another way as well but it requires some modification of the cell. Placing a resistor across the voltage leads will increase the measured current of the cell so it will detect a higher current than there really is.

You would place the resistor across the black and white wires shown here:

1727273870736.jpeg

The max current that is currently being drawn is 2.62A. Which leaves a margin of 5.37A below the 8A limit. So if the supply voltage is 26.5 volts, the smallest resistor that one could use is 4.94 ohms. But that leaves no margin. I would target a 7A limit which results in a 6 ohm resistance. However, you would need to find one that is rated above 120 watts or 2x12 ohm resistors in parallel at 60 watts each such as these:

 
I am not sure why you are opposed to troubleshooting the cell because it is not operating within normal conditions.

Have you tested the cell at a pool store? Many pool stores have the test equipment to test cell itself. Do not rule this out until you have had the cell actually tested.

Also, there is a solder joint on the Hayward SWG boards that typically goes bad and when it does, it creates higher resistance than normal which in turn reduces the current through the cell and the displayed salt is lower than normal. So this is another area that could be looked into to solve this issue.


Also, do you understand how a Salt/TDS meter works? It measures the water conductivity (µS/cm from volts, amps, water temperature) and then calculates the salt level using a conversion factor (e.g. 0.5).

It is exactly the same way the T-15 & control unit determines salt level. However, the cell plates are used as the sensors and not separate probes. So it is not like the temperature sensor which can be replaced with another temperature sensor or a resistor. The SWG plates are part of the salt measurement.

The unit uses shunt resistors to measure the current via a voltage across the shunt resistor. Theoretically, one could modify the board so that the unit shows higher amps and higher salt level that it would normally by increasing the resistance of the shunt resistor. However, this is not without issues. First, it would require modification of the board and second it would reduce both the current and voltage in the cell itself although the SWG display may show higher current & salt levels. The effect would be a reduction in CL production of the cell.

Another option is that you could put a high powered resistor across the power leads to the SWG cell which would increase the current draw from the SWG controller and it should then read higher amps and higher salt level as well.

But both of these solutions are not really solutions but are putting a band aid on a bleeding artery. You really need to find out what the problem is first or you could possibly cause more damage to the unit and in the end cost more to repair.
Mark, first of all I just want to say that I really do appreciate your technical support with this SWG and I do apologize if I sound a bit forward but I have been around the block several times with the Hayward Acurite SWG and I'm tired of replacing cells. Yes, I know its the cell. I'm done with testing the cell as in the past and replacing it when it the chlorinator function works just fine. Just will not maintain an accurate ASR according to salt test of the pool. These units should allow for a manual override function at an additional cost or course for temperature and calculated salt reading. The two major device failures on the Hayward SWG.

I understand now that there is no salinity sensor like the temperature sensor in the cell. For the past several years I've had the issue over time with dropping ASR with each new cell I buy. Not at first, but gradually the same symptoms return. I'm now looking into taking a more technical approach to trying to override/bypass the ASR reading.

I know how to accurately test the salt level of my pool with the test kit and now with the electronic tester. I've been tested salt level way before the electronic devices came available. I do understand how a Salt/TDS meter works (µS/cm from volts, amps, water temperature) and then calculates the salt level using a conversion factor. And this is why I know there is a way to override/bypass the reading the salt cell is sending back to the board.
I like the idea or increasing the resistance of the shunt resistor. I don't care if the effect world be a reduction in chlorine production of the cell. The chlorine production of the cell has never failed on any cell that I've had to replace.

So I'm interested in knowing what components and the value of those components need to be in order to make the modification myself and to know where to look and repair for cold solder on the board. I've never had to replace the board on my SWG so its not going to upset me too much if I in some way I accidently short or burn so major components in process. I did received an Associates degree of Applied Science in Electronics right out of high school but never had the opportunity to apply it in a real job career.

Thanks again in for your help.

DennisK
 
Change the cell type in the settings to see if that helps.

Changing the cell type changes how the salinity is calculated.

If you have a T-15 and you select a smaller cell in settings, it will increase the salinity reading.
 
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So I'm interested in knowing what components and the value of those components need to be in order to make the modification myself and to know where to look and repair for cold solder on the board. I've never had to replace the board on my SWG so its not going to upset me too much if I in some way I accidently short or burn so major components in process. I did received an Associates degree of Applied Science in Electronics right out of high school but never had the opportunity to apply it in a real job career.
First, try removing this jumper:

1727534197641.png
 
Change the cell type in the settings to see if that helps.

Changing the cell type changes how the salinity is calculated.

If you have a T-15 and you select a smaller cell in settings, it will increase the salinity reading.
The R1.40 doesn't give me that option.
 
Keep in mind that your time with this cell is limited. You may get a few more months but production will steadily decrease until it completely fails.
 

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Keep in mind that your time with this cell is limited. You may get a few more months but production will steadily decrease until it completely fails.
Okay. I understand. But then I don't usually have to replace my cell due to lack of chlorine.
I reset ISR to my current tested salt reading. Lets see if it will maintain my 3300 or for how long.
I need to to know if switching to the T-5 cell raises the calculated ISR due to bypassing circuit on board to false values to limit current induced by calculated the load. This has to do with less current being drawn on this new load? This would make sense to what you said about adding a shunt of a lower resistance to divert it while using the existing T-15 cell.
I would love to get my hands on the full schematic for this board.
I would like to be educated more on the specification details if you are willing to provide more information.
Thanks again in advance for all your help thus far.
 
The instant salinity reading is calculated based on the water temperature, voltage and current compared to the expected current for a new cell.

Hayward knows what the current should be for each cell at different salinity levels and water temperatures.

If you change the salinity or water temperature, the current should change by a specific amount according to the equation.

It is a similar, but not exactly the same principle as a conductivity meter.

A conductivity meter measures conductivity and temperature and then calculates the salinity according to the equation.

For example, if you know the conductivity, you can use the graph below to determine the salinity.

The graph can be converted into an equation.

The graph is at a specific water temperature (probably 25 C/77F).

For best accuracy, you need the graph or equation that applies at the water temperature of the pool.

1727585303981.png
 
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Okay. I understand. But then I don't usually have to replace my cell due to lack of chlorine.
I reset ISR to my current tested salt reading.
That only works for so long but in T-5 mode, you can extend that time a bit. Eventually, the cell will degrade so much that you will need to replace it. Have you even had to replace a SWG cell? If not, you are lucky so far but it is in your future no matter what. These cells do not last forever. Like brakes in a car, eventually they get worn out.

Lets see if it will maintain my 3300 or for how long.
It will take some time but the Hayward controllers will shut down the cell when the salt reading reaches 2400 ppm.

As the cell ages, the rare earth metal coatings tend to flake off and become corroded. Periodically, you can perform an acid soak of the cell and remove this corrosion. You should see a jump in amps and displayed salt level after the soak but I found the boost doesn't last more than a few weeks before the salt level starts to drop once more. But it can extend the life a bit more.

I need to to know if switching to the T-5 cell raises the calculated ISR due to bypassing circuit on board to false values to limit current induced by calculated the load. This has to do with less current being drawn on this new load? This would make sense to what you said about adding a shunt of a lower resistance to divert it while using the existing T-15 cell.
As @JamesW pointed out, it is due to the change in the way the salt level is calculated. Nothing in the circuity is changing, only the programing, which is really a better solution for as long as it works.

T-5 has a smaller total plate area than the T-15 so at the same salt level, the T-5 will consume less current than the T-15 and this needs to be taken into account when calculating the salt level. One way to think of it is that the T-15 corrosion is reducing the effective area of the cell and making it look like T-5. This is why when you switched from T-15 to T-5 mode the salt level jumped up.

I would love to get my hands on the full schematic for this board.
There is a partial schematic here:

I would like to be educated more on the specification details if you are willing to provide more information.
Sure, ask any questions but there is a ton of information in the Wiki article I posted above so start there.
 
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Perhaps a little more history about your pool, how you care for it, and your experience with Hayward SWGs might be helpful.

It’s sounds like you’ve gone through a number of them with failures - exactly how long do you get out of cell before these troubles start? Most folks on average can get a good 5 years out of an SWG before they become problematic. My first Pentair lasted over 8 years before I had to replace it. The second is only 3 years old but will be replaced sooner rather than later because the body of the cell is starting to show a weeping leak. That’s manufacturing defect, not a generation/plate failure per se.

If you keep running into these cell failures then it may not be an issue with the cells but rather something more in depth such as pool chemistry or operation issues. The premature cell failures may simply be the “canary in the coal mine” telling you there’s something else problematic happening.
 
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The production is roughly proportional to total plate surface area.

If the cell is a T-15, changing the cell type increases the salinity reading by a factor of:

T-3 = 2.77
T-5 = 2.00
T-9 = 1.5
T-15 = 1.00

Changing the cell type from T-15 to T-5 should double the salinity reading.

T-15 has 13 Titanium Plates, 150 x 63mm. Produces 1.47 lbs/day.

T-9 has 13 Titanium Plates, 101 x 63mm. Produces 0.98 lbs/day.

T-5 has 7 Titanium plate, 150 x 63mm. Produces 0.735 lbs/day.

T-3 has 7 Titanium Plates, 101 x 63mm. Produces 0.53 lbs/day.

Each plate has two sides for a total of 26 surfaces and 14 surfaces.

I think that the outside surfaces of the outside plates do not produce, so you have 24 producing surfaces for the 13 plate models (12 (+) and 12 (-)) vs. 12 producing surfaces for the 7 plate models (6 Positive (+) and 6 Negative (-)).

The cell is a bipolar cell with only the outer plates being connected to the DC source.

The water between the plates acts like a battery with a positive and negative terminal in a battery charger being charged with 6 batteries in series and two sets of 6 in parallel for the 13 plate models.

The negatively charged anions (chloride) are attracted to the positively charged anode where they lose an electron to become a chlorine radical and they combine with another chlorine radical to produce chlorine gas, which dissolves into the water.

(+) Anode 4Cl- -> 2Cl2.

(-) Cathode 4H2O -> 2H2 + 4OH-.

2Cl2 +2H2O -> 3H+ + HOCl + OCl-.

HOCl + OCl- + uv light -> O2 + H+ + 2Cl-.

Following the process, we can see that there are 4H+ and 4OH- created, which nets out to pH neutral.

The chlorine gas generated is very acidic and creates 3 hydrogen ions for every 4 hydroxide ions created.

As the hypochlorous acid is broken down by UV, 1 more hydrogen ion is created for a net neutral result.

Assuming that chlorine gain and loss are equal, there's no pH rise.

High pH at the cathode creates calcium carbonate scale, so the polarity reverses to minimize scale buildup.

1727626758996.png


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2Cl- - 2e- --> Cl2

2H+ + 2e- --> H2

In any case, the number of electrons leaving the power supply have to equal the number of electrons returning to the power supply.

The number of moles of chlorine gas produced will equal the number of moles of hydrogen gas produced.

DC power supplies, including batteries, have a positive terminal and a negative terminal.

Electrons leave the negative terminal and return to the positive terminal.

Due to an unfortunate technicality, current is defined as the flow of positive charge, so current flows from the positive terminal to the negative terminal, which is the opposite of the flow of electrons.


1727629930159.png
 
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The water between the plates acts like a battery with a positive and negative terminal in a battery charger being charged with 6 batteries in series and two sets of 6 in parallel for the 13 plate models.
Charging batteries in series requires a DC source that is the total of all battery voltage added up.

In the below example, there are (2) 12 volt batteries being charged in series and the power supply is 24 volts DC.


1727796803638.png

For a 13 plate salt system at 24 volts and 6 amps, the water and ions in the 12 gaps between the plates is like having 2 sets of (6) 4 volt batteries in series and the sets are in parallel.

Each set uses 3 amps for a total of 6 amps.

Each "battery" is getting 4 volts and 3 amps, which is 12 watts.

12 watts and 12 cells = 144 watts of power being used.

This energy is being stored in the Hydrogen and Chlorine gasses being produced.
 
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