Salt Cell Post Mortem #2

[DeadAquaRite]

Five years ago I hacked apart my dead Hayward T-15 for "science". This week my Chlorinator Pro CP-15 gave up the ghost. Once again, I disassembled it and here are the pictures...

Notes:
- The electrodes were not corroded. They broke during violent disassembly.
- The sealant was not tar like. It felt and smelled like epoxy.
- Plate erosion was minimal.
- The coatings were mostly deep black and paper thin.
- Cell took 2-3 hits with a 3# hammer before breaking. NUMEROUS hard strikes to separate and open.

Plate Erosion

https://i.ibb.co/6R6tTks/20200725-215729.jpg

#3 - Free floating plate

https://i.ibb.co/RTC048V/20200725-215123.jpg

Broken plate-electrode weld

https://i.ibb.co/h1JG32B/20200725-215745.jpg

https://i.ibb.co/CwPcqyV/20200725-215725.jpg

https://i.ibb.co/mqNv6Vd/20200725-215717.jpg

Floating plate wire brushed

https://i.ibb.co/dPgH4X6/20200725-215209.jpg

https://i.ibb.co/g6BGm9m/20200725-215643.jpg

Three electrodes broken away from plates

https://i.ibb.co/0Ywp7LF/20200725-215756.jpg

https://i.ibb.co/WH0JF0f/20200725-215024.jpg

Drilling into sealing epoxy

https://i.ibb.co/M2VVXzm/20200725-214648.jpg

https://i.ibb.co/0FsLz8k/20200725-215234.jpg

First 5 plates

https://i.ibb.co/hDhDFQz/20200725-215638.jpg

Middle three plates

https://i.ibb.co/BrNS4SP/20200725-215649.jpg

Right 5 plates

https://i.ibb.co/rx53zWD/20200725-215653.jpg

Temperature sensor?

https://i.ibb.co/xjXMQRh/20200725-214653.jpg

Plate Carrier

https://i.ibb.co/mSN9Xz5/20200725-215832.jpg

Plate and broken electrode, in carrier

https://i.ibb.co/GpWrJV2/20200725-215040.jpg

https://i.ibb.co/VgjQ1QN/20200725-215035.jpg

 

[mguzzy]

Well done! This is twice you have jack hammered a SWG.. I think this now counts as a hobby, Would you mind updating your signature?

 

[chlorinatorpro]

Good job. It takes awhile with heavy hammer but is so much fun. Nice ole industrial bandsaw is much easier. Got to remember these are the AFTER pictures on the plates from almost five years use. Yes, epoxy.

 

[DeadAquaRite]

Good job. It takes awhile with heavy hammer but is so much fun. Nice ole industrial bandsaw is much easier. Got to remember these are the AFTER pictures on the plates from almost five years use. Yes, epoxy.

Unfortunately, I don't have one of those. And I'll admit I was surprised when it took the first blow from an 3# hammer (on a seam) and didn't even crack. Very solid construction.

Yes, those are after pictures. And the plates looks surprisingly good, especially when compared to the T-15 plates. On the T-15 the failure mode was obvious, the electrode corroded in two. Here there was no obvious damage, save a tiny bit of erosion. What do you think the failure mode was, coating failure?

 

[mistah_t]

DeadAquaRite - for what it's worth, googling in the hopes of finding someone who had torn a salt cell apart, I stumbled upon your post mortem(s). After some careful hacksawing and tedious epoxy removal, I discovered that my 3 year old Hayward t-15 failed in a similar fashion as yours. the middle anode post had completely corroded and the middle plate was floating free. Not to mention some crazy deterioration of the plate itself (the rest of the plates seem perfectly good).

Long story short - I inherited this pool about 8 years ago and have gone through a couple of cells. With the most recent failure, I was curious to see if I could frankenstein one back together (given that cells seem to cost more than printer ink these days) and based on initial tests, it might work. I extracted a plate from a "dead" generic cell I had ordered a few years ago which still had 2 good anodes attached to plates 1 & 13. Placing that in the middle along with some titanium threaded posts to extend far enough up into the housing. From there I reconnected the wires and did a quick "bucket-o-salt" water test with the cell. Once my controller kicked the cell on, it immediately started working and producing bubbles.

I've ordered some titanium threaded rod (ebay - probably reclaimed medial devices) to help with future anode jerry rigging and now I just need to see if my make-shift drain pipe PVC coupling will successfully rejoin the split housing. Anyway, just wanted to say thanks for the posts and details you've provided over the years. If this actually ends up working, I'll make a detailed post should anyone else want to give it a shot.

 

[JamesW]

I would note that any modification is not recommended and it should only be done based on one’s own decision based on their own research and at their own risk.

 

[DeadAquaRite]

DeadAquaRite - for what it's worth, googling in the hopes of finding someone who had torn a salt cell apart, I stumbled upon your post mortem(s). After some careful hacksawing and tedious epoxy removal, I discovered that my 3 year old Hayward t-15 failed in a similar fashion as yours. the middle anode post had completely corroded and the middle plate was floating free. Not to mention some crazy deterioration of the plate itself (the rest of the plates seem perfectly good).

Long story short - I inherited this pool about 8 years ago and have gone through a couple of cells. With the most recent failure, I was curious to see if I could frankenstein one back together (given that cells seem to cost more than printer ink these days) and based on initial tests, it might work. I extracted a plate from a "dead" generic cell I had ordered a few years ago which still had 2 good anodes attached to plates 1 & 13. Placing that in the middle along with some titanium threaded posts to extend far enough up into the housing. From there I reconnected the wires and did a quick "bucket-o-salt" water test with the cell. Once my controller kicked the cell on, it immediately started working and producing bubbles.

I've ordered some titanium threaded rod (ebay - probably reclaimed medial devices) to help with future anode jerry rigging and now I just need to see if my make-shift drain pipe PVC coupling will successfully rejoin the split housing. Anyway, just wanted to say thanks for the posts and details you've provided over the years. If this actually ends up working, I'll make a detailed post should anyone else want to give it a shot.

View attachment 437554

Definitely keep me posted on the results. This is a feasible method to get 1-2 more years out of a "dead" cell. My biggest fear has always been an unexpected rupture in the modified cell, resulting in an empty pool.
Do you have a picture of the assembled product?

 

[mistah_t]

I would note that any modification is not recommended and it should only be done based on one’s own decision based on their own research and at their own risk

Yeah that's a big 10-4. Having spent the last several (sweaty) weeks installing and configuring harborfreight-like LiFePO4 battery banks 2 inches above 24 gallon diesel tanks, #fatetempter seems to be my new brand. That said, when your iq-level is as low as mine, these things seemingly are a few 20 gauge metal plates with 3 cents worth of radio shack crimp-on terminals slapped on the ends. The proprietary PVC housing is the primary PIA. There's always a chance I could fry my vintage aquarite control board, but I'm honestly tired of playing ship of theseus with that thing, mouser and relay soldering.

Definitely keep me posted on the results. This is a feasible method to get 1-2 more years out of a "dead" cell. My biggest fear has always been an unexpected rupture in the modified cell, resulting in an empty pool.
Do you have a picture of the assembled product?

I'm planning to slap it together at some point today and will try to do a better job documenting the trials/failures. I was hoping to come up with a make-shift union of sorts so I could maybe crack it back open, but I'm leaning toward good ole pvc glue and a proper coupling to minimize the risk of a leak/rupture. I have more 3m 550FC lying around than I know what to do with (and it expires), so I'm hoping that makes up for the limited flange I left myself with the dissection. Worst case I'll see how all these fancy "engineering" resins work out with my 3d printers or just snag a generic swg housing off ebay to mod. For "science"

And IF the Ti terminal idea works out, I have a feeling I could get more than a year or two out of this hacking with the 10 or so seemingly good plates I've cobbled together. I could be wrong, but I don't think anything was welded or brazed in place. On both the hayward and generic cells, it looks like a purely mechanical connection (slit+crimp) but I could be wrong or whatever was there before was the first thing attacked as things deteriorated. But those are just my discount GED-musings.

I'll report back later! Probably with desperate pleas for help fixing everything I've broken.

Side note - I guess I'm just super dumb dumb when it comes to Ti. I thought it was about as inert as you could get. Maybe insane pH level will do that over time (the alligator chomps on that plate). And for reference, before my hacking, the cell was reporting +/-24ish volts, 0.1amps and 0000ppm. I tested the water last week with salt strips and actual levels were insanely high (5200ppm - me or the wife/kid probably dumped too much in as the cell was failing and reporting low salt). Might be hard to tell from my one-handed video screen grab, but that reading isn't too far off in this quick bucket test. Anyway, I'm off to re-crimp the wires I nicked with the dremel and to see how well my glue job holds.

 

[mistah_t]

I need to grab some proper 10x macro shots before I glue things up. Again, I could be wrong, but I didn't see much indication of "hot glue" on the plate and rod/anode/electrode/whatever it's called on Mcmaster. I didn't get a good shot on the generic cell, but it's even more obvious on that one and I initially suspected it could have contributed to the failure. Poor terminal contact with electrical never seems like a good thing.

If anyone has a suggestion for a sacrificial anode to add into the mix, I'm game to slap something in. Also what's an anode.

 

[DeadAquaRite]

I guess I'm just super dumb dumb when it comes to Ti. I thought it was about as inert as you could get.

Remember, you've got electrolytic action, plus YEARS of 100gpm flow, plus salt and chlorine (an oxidizer) on the surface, all acting at the same time. It's probably leached away 1 or two atoms per second, over millions of seconds. Based on the other plates, I suspect electrolysis is responsible for the bulk of the erosion.

If the cell is the right size, a threaded joint or union would be fantastic. My personal choice for this would be JB weld, and I would try and create some grooves in both parts to create a mechanical connection. That tube is roughly 2.5in, and with a max water pressure of 25psi, there would be about 155# force on each end, creating 310# in tension at the joint.

 

[mistah_t]

In hindsight, I should have paid a bit more attention to your original teardown photos. Didn't have much of a plan when I started cutting and figured I'd follow the visible seam on the housing to see how it was initially put together. If I were doing it over, I'd use a band clamp as a guide and cut right in the middle of the "thick" part (which happens to be ~4 inches). I believe that would give enough of a lip to use a piece of 4" schedule 40 pipe as a slip-on coupling for an almost factory fit (if the blade kerf is tiny). That's what I get for being a tinkerer and not thinking it completely through. That said, I think there is enough material here to use your suggestion of building up the connection points with some JB Weld. That would likely work just dandy for whatever remaining life this abomination might have.

Probably hard to follow my "process", but I've got to clean up for a dinner date. I'm letting the craptastic PVC glue and beads of 3m 550FC cure overnight before I give this sucker a test drive in the morning. If it looks like it'll work for more than 10 minutes, I'll encase that SOB in resin if it means I don't have to drop $900 on a new cell for a few months. Also I need to figure out this image/gallery setup.

 

[DeadAquaRite]

$900? I bought a chlorinatorpro for ~$350.

 

[mistah_t]

$900? I bought a chlorinatorpro for ~$350.

I haven't done a deep dive recently, but just assumed that prices doubled everywhere the last few months. Where and when did you score one? I briefly checked out their site and it looked like t-15 equivalents were $579 but with the fine print:

Due to supply chain shortages related to COVID, Chlorinator Pro is out of inventory and is not shipping orders. We have no ETA at this time. If you place an order please be aware that it will not ship until inventory has been received. We apologize for the inconvenience.​

Hopefully someone eventually tells the supply chain "daddy chill" and things settle down a bit.

 

[mistah_t]

Quick n dirty update. In my haste to test this out, I managed to pick up my caulk gun loaded with butyl sealant. Made a wonderful mess. Poorly cleaned it and used some marine sealer in lieu of proper epoxy for now. I also took inspiration from your JB Weld suggestion and put a few "tack welds" around the new joint as backup for the PVC glue and 3m 550fc. If the unit seems stable, I'll 3d print a mold for the joint area and incase the Crud out of the thing with some two part jb or marine resin.

Operational Test: Installed it this morning for a pressure test and everything seemed a-ok. Removed it from the pump, screwed in a bypass and performed another bucket test with some diluted water. Salt strip reports ~2600ppm and the cell/system settled on 2400 running for 1 minute. The pool water itself needs a good bit more dilution, but so far I'm optimistic given I didn't expect much more than some smoke, regret and possible minor electrocution.

 

[DeadAquaRite]

Where and when did you score one?

Based on my last post, 4 years, 291 days before July 22, 2020

 

[mistah_t]

Another mediocre update: Cleaned up some of my slop-job work, and got my salt levels down from crazy town (currently ~3500ppm). Cell has been in place for 7 days now with no visible signs of leaking, stress or anything really other than being fugly. Slowly increasing the percentage of run-time on the system and currently testing things out with the chlorinator set to 55%. Chlorine levels are improving (TC/FC) but it's been raining like crazy so it's a dice roll from day to day with pH and overall balance.

Only issue so far is I thought I thoroughly checked the cell during my bucket tests and didn't notice and big polarity variances. But since my "clean up" work, I'm now seeing a good bit more resistance (or higher amps - I'm also ignorant on the electrical side of things) when the polarity switches to negative. I've replaced relays and re-soldered several points over the years (and recent weeks), so it's possible a fresh dab on ole K1 might restore balance. That or it's one side of the plate(s) giving up the ghost. Either way, I'm pleased with my first half-Rear attempt and already looking for another donor cell to work on. If no one around town has one lying around, I'll hit up the interwebs. That and order some proper electrical potting goop to make the restoration efforts significantly easier.

 

[mistah_t]

Quick update - Franken cell lasted a little over 14 months before degrading to the point of "not worth it" and no longer maintaining chlorine levels. I had a rough idea of a new approach but put it on the back burner until the universe forced my hand. The "new and improved" version addresses most of my annoyances and in limited testing, performs far better than the initial build. I'll post a detailed breakdown for anyone with more time than sense and a desire to waste a few days of their life in exchange for 1.) a band-aid cell 2.) a fried pool system and expensive overhaul

For now, a few random GED observations:

• That center anode really seems to eat Darn more often than not. I've procured about 7-8 different cells (t-15, t-9, t-3) and brands, and almost all of them are gone/broken/crusty. I haven't spent anytime understanding how these cells even work, but I'm guessing that center anode/plate take the full amperage dose and whatever science reaction happens compared to the 2 edge plates. Or...
• The anodes and plates do indeed seem to be titanium. I had assumed the nuts slathered in potting resin were also titanium, but that is not the case. I honestly don't even know if they're proper stainless (or what grade). I'm consistently seeing rust spots as I tear into these things which I assume isn't great. Also, 9/10 times I see evidence of rust around the anode (stained PVC), it's the broken/corroded culprit.
• One thing possibly contributing to failure (overall or early) are bad o-rings where the anodes meet the housing. Metric neoprene P5s seem to match (4.8mm).
• The anode (are they anodes?) to plate connection is definitely more than mechanical. I've gotten enough practice separating them with minimal damage to see the typical spot-welding prep, which makes sense I guess. It's easy enough to replicate with an 1/8" cobalt drill bit, patience and harbor freight coupon (if you don't already have a spot welder). One could try using an arbor press or the like to bypass the spot-welding, but I wouldn't count on it surviving or maintaining good contact during reassembly. Also, alignment of the anode to plate is pretty important (ask me how I know).
• Mileage varies based on brand/housing dimensions, but minor modifications to a 90mm PVC union off eBay or aliexpress works surprisingly well. My original plan was to toss one onto the mini-lathe to get me closer to the 92mm and change diameter needed for hayward t-cells, but I opted for the dumb but quicker 3-5/8" (92mm) hole saw in my tool kit.
• I opted to try beeswax for potting the terminals/anodes this time. Thought it would make re-entry a bit easier. It does but it's overkill (IMHO). This time I decided to 3d print a gasket out of ninjaflex, but that too is just a waste of time (isn't it all). Oversized m5 stainless washers BACKED with some Permatex Ultra Black or the like works just fine. I opted to use m5 titanium nuts to see if that makes a difference with the rust/corrosion issue at all. Probably not, but cells aren't getting cheaper so why not.
• I fully believe (in some instances), there are nearly 10 out 13 plates in these cells that are still viable. We'll see moving forward.
• I may or may not have successfully spot welded shorter t-3 plates together as a joke that surprisingly worked.

I'm sure theres more, but I ramble too much anyway. So far so good. I plan to hook up a current/voltage sensor to the cell with an esp32 to log readings every few minutes into my Home Assistant setup. The math my aquarite controller is doing isn't fancy and mostly I just want to have more solid data moving forward on it's performance (operationally). A few random pics.

 

[SumOfOneInteger]

@mistah_t Your self deprecating humor and propensity for tinkering and redneck rigging leads me to believe that you may be me. But the fact that your location is Louisiana and I’ve never been, along with the fact that I don’t remember writing this, or disassembling a SWG, leads me to believe that you are not me. Big, if true. Either way, I like the cut of your jib and would drink numerous beers with you while discussing stupid diy engineering antics.

 

[mistah_t]

@mistah_t Your self deprecating humor and propensity for tinkering and redneck rigging leads me to believe that you may be me. But the fact that your location is Louisiana and I’ve never been, along with the fact that I don’t remember writing this, or disassembling a SWG, leads me to believe that you are not me. Big, if true. Either way, I like the cut of your jib and would drink numerous beers with you while discussing stupid diy engineering antics.

I popped back over here to post a quick update and just saw your comment. Fate screwed us both because I literally just got back from Orlando a couple of weeks ago. My visit had nothing to do with ai, 4090s or pizza from Prato (which was pretty freakin good btw). Wish I had seen this sooner so we could have met up to trash the Tesla 3 I rented (verbally, not culvert hopping). It's also entirely possible you're me/me you and the beer causes login mix ups. Either way, I'll holler next time I pop down to decipher which baggage claim I'm supposed to head to (wtf even is A or B?).

On the JankyCell front(still workshopping the branding), the mofo is performing... like stupidly well. I'm sort of confused having expected it to poop the bed after a few hours. 50% @ 10 hours a day is keeping everything hunky dory (occasionally a bit high with less sun the last few weeks) and I just got my first "low salt" indication in a couple of months. Perfect timing to tear everything down and plumb in a new variable speed pump and prep for winter (as if we get one this far south). I plan to eventually Chatgpt a post with my step-by-crappy-step process. That said, if anyone around here has a viable donor cell lying around, I'd be open to trying to revive one for someone else since it's far more motivating than doing something for myself or a task that I should be doing.

 

[SumOfOneInteger]

I love trashing teslas and Prato’s pizza. Also if you loved terminals A & B we now have C that just opened and D that’s in the planning phase! How fun that’s gonna be!