Intellichlor Internal Salt Level Calculation

marktrimarc

Member
Feb 6, 2014
8
Colleyville, TX (D/FW)
Hi, my name's Mark. I've been a member since 2014 and have posted a few times, but have never started a thread before. I've been maintaining my salt pool for about seven years, and am pretty knowledgeable about everything related to it. I'm always watching eBay for used IC-40s that either work or can be repaired (I know, it's very rare that you can repair one).
I purchased an IC40 on eBay recently that was being sold for "parts or repair". The seller said that he had put a new flow switch in it (turns out it was a Compool aftermarket one) but it still showed "Very Low Salt" after booting up. I got it (including shipping) for the cost of the new flow switch, so it was a no-brainer.

Here's the issue:
I installed a new Pentair flow switch in the non-working IC40, just in case the "new" Compool one that came with the unit was bad. I still get the Low Salt reading light on the cell itself, and my handheld controller reads 1,050 ppm from the cell. With the Compool flow switch still installed, it showed 1,050 ppm salt, as well. I'm thinking that 1,050 ppm could be the default reading if the cell is unable to calculate the true salt level. If it's zero, please let me know.
When I have my"working" IC40 installed, it shows a salt level of 2,850 ppm and my Oakton electronic Salt Tester reads about the same. I know 2,850 is a bit low, but my good IC40 is producing chlorine at that salt level (water temperature is about 65 F).

I've read as much as I could find on TFP about how the Intellichlor calculates salt levels using a combination of temperature and conductivity.
Having tried two different (new) flow switches, I can assume that the temperature reading coming from the flow switch is not at fault.
So, that leaves an internal problem with the unit being unable to calculate salt levels.

So, finally, my question:
Would there possibly be a way (maybe by splicing a resistor into the temperature circuit between the flow switch and the cell) to trick the cell into thinking the water is a much higher temperature and therefore allowing the salt level calculation to take place?
I only ask this because it's reading 1,050 ppm salt, as opposed to zero ppm, and increased temperature calculates to higher salt levels.
If not, what might be the fault inside the cell to cause its inability to calculate salt levels? I know these cells are not repairable.
If so, any idea on what size resistor to try? If higher resistance doesn't equate to higher temperature, let me know. That's another assumption I've made.

P.S.: Jim Rahbe, if you're reading this, I probably live a couple of miles from you, as I'm on the border of Bedford and Colleyville (Texas).
 
Last edited:

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
19,811
Bedford, TX
Mark,

Welcome neighbor!!

If you cut the wires going to the thermistor, the cell will think the water temp is 77 degrees.

Here is one way to remove the thermistor from the flow switch and use a standard 10K thermistor in its place.

Temp probe hack.jpg



Sorry, but I think your cell is bad.. But then, I've been wrong about 100 times, just today.. :mrgreen:

Thanks,

Jim R.
 
  • Like
Reactions: setsailsoon

marktrimarc

Member
Feb 6, 2014
8
Colleyville, TX (D/FW)
Thanks, Jim. I think you're right about the cell being bad, as 75 degrees is not much different from the current water temp. Maybe as a last resort, I'll try what I suggested earlier and splice in a resistor rated higher than 10k to (by chance) increase the calculated salinity to above 2800 ppm and get it working, unless the cell is currently making no calculations.
 

marktrimarc

Member
Feb 6, 2014
8
Colleyville, TX (D/FW)
So, I checked the resistance across the white (temperature) wire and the green (common) wire on a Compool flow switch and it read about 11,000 ohms at 72 degrees and 4,000 ohms at 110 degrees (dipped flow switch in warm water). So, the resistance across the thermistor varies inversely with its temperature. I was expecting a proportional relationship.

Therefore, I'll buy a 4,000 ohm resistor and put it in place of the thermistor in the circuit going back to the cell (across the white and green wires coming from the cell). It will simulate 110 degree water and if the salinity still reads 1,050, I'll know it's a failed cell for sure. I'll post the results here when it's been done, in case anyone runs across this thread.

This raises the question; How can zero resistance (cutting the white wire between the flow switch and the cell) cause the cell to think it's 75 degrees as many people report? I guess the cell defaults to a temperature of 75 degrees for the salinity calculation when there's no resistance from the white wire (such as with a failed temperature sensor).
 

marktrimarc

Member
Feb 6, 2014
8
Colleyville, TX (D/FW)
James, sorry for the late reply. I also meant to update the results of my "experiment" with resistors in the circuit:

I bought a potentiometer on eBay with a maximum resistance of 15k Ohm and spliced it into the temperature circuit of the "bad" IC40 chlorinator. I essentially removed the flow switch from the temperature circuit (white wire) and substituted a resistor, going back to the IC40 via the green wire.

With the IC40 installed in my pool piping, when I dialed in various resistances, ranging from 15k Ohm down to as low as it would go (simulating various temperatures), the chlorinator never read anything other than 1,050 ppm salt and had the Very Low Salt light on. I also cut the white wire and the salinity reading was still 1,050. Apparently that's the default if the unit can't calculate the salinity for some reason. Thanks for the infinite resistance correction (for an open circuit), by the way.

So, I trashed the IC40.
 

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
19,811
Bedford, TX
Mark,

Besides the fact that you SWCG is bad, your "test" failed because the cell only measures the salt level at start up and every 12 hours after start up.. It could not care less what happens in between... :(

Thanks,

Jim R.
 

Dirk

Gold Supporter
TFP Guide
Nov 12, 2017
7,720
Central California
Pool Size
12300
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Too late now, I suppose, but Pentair ICs have a built-in "hour counter" that indicates how much life they've got left. Instructions are in the manual. That should be part of your IC-resurection process...
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
21,195
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
Pentair ICs have a built-in "hour counter" that indicates how much life they've got left.
Pentair ICs have a built in hour counter that indicate the usage time, not the time left. You don't know how many more hours you have left.

Pentair says cells should be good for 10,000 hours however many cells do not make it that long. Once you are past 6,000 hours you are generally on borrowed time. Acid cleaning of the cell will reduce the remaining life and not show in the hour indication.

How to Determine the IntelliChlor Cell Usage
Pressing and holding the “More” button launches the System Status Mode. When the lights finish scrolling, the percent lights indicate hours of usage in 1,000s. For example, if the 40% light lights, that indicates 4,000 hours.