Aquarite current changes with polarity

[mikemo]

Hello everyone. I started thinking that my control box was failing, but now I'm not so sure. Cell is a T-15, about 5 years old. Current salt level is 3000ppm (tested twice).

Polarity 1
Voltage 23.8V Current 5.22A

Polarity 2
Voltage 29.2V Current 1.10A

When the box is working in "polarity 1" mode, you can see (and measure) chlorine output. When in "polarity 2" mode, no bubbles and almost no chlorine production.

I took a look at the circuitry in the control box and it is very simple. The two relays, depending on which one gets switched on, simply reverse the power leads to the cell. The return current goes through a sense resistor, to ground. I thought that maybe one of my relays had a bad connection (the solder work was poor) so I resoldered the pins. No difference. Now I'm reading that what I'm seeing might be the cell itself failing and not the control box.

Any insight will be greatly appreciated. I'd hate to drop $500 on a cell when the control box is the problem.
Thanks!
Mike M.

 

[ping]

Make sure the cell is clean and all scale has been removed. If you get the same symptoms with a clean cell then most likely the cell is worn out.

After checking the cell for scale do the same test while displaying the instant salinity numbers to see what those are. My guess is the bad side will show low salinity.

Check a local pool store to see if they have a Hayward cell checker. Most Leslie's have them.

 

[mikemo]

Thanks for the info. So this would not be "out of the ordinary" for a cell to act this way, with asymmetric current flow? I guess it's time to fork over the money for a new cell.

Are there different sets of plates inside that operate when the polarity is reversed?

Sorry, one more question. Is it worth paying an extra $100 for the "long life" cell from Hayward? T-15 vs. t-cell-940

Thanks again
Mike M.

 

[ping]

T-15 cell produces 580lbs of chlorine gas in its lifespan and the 940 can make 725lbs. The T-15 should have a 3 year warranty and the 940 should have a 4 year warranty. Do the math to see which one is the better deal for you.

One side usually wears faster than the other and you can see by the instant salinity levels.

 

[mikemo]

I understand. I have an older controller (installed in 2004, r1.32) and I'm wondering if it is compatible with the 940.

I'm also curious if the 940 is the exact same cell as the T-15 but with a different warranty. I noticed that you can buy the T-15 from many places online, but I can't find where a 940 would be available anywhere but my local pool store. Is this just to keep the local stores happy and allow them to compete better with the online retailers?

Thanks again for all the help.
Mike M.

 

[ping]

The 940 is typically a brick and mortar item with a 4 year warranty. The T-15 and 940 will produce the same amount of FC each day and are equivalent to each other in all respects except the lifespan of the 940 is longer.

 

[mikemo]

Thanks. Sorry for not being clear.

What I was looking for is if the cells (the T-15 and the 940) are actually built differently, or if the extra money for the 940 was simply covering the extra year of warranty (and a different sticker).

Thanks.

 

[ping]

Electronically both cells are the same, the 940 has thicker plating on the plates which allow them to make more chlorine over the lifespan of the cell. They both will produce the same amount of chlorine daily.