Autopilot cell shorted out

Billhev

New member
Aug 8, 2010
2
I replaced my Autopilot SC48 cell this April due to the low volts and basic wear out of the old cell (got 4 years out of that one). I went with a generic replacement cell which seemed to be working great. When I came home from vacation last night I was getting an error message advising to check the orp control. When I checked things out I saw that my cord to the cell and the cell had shorted out/fried. Here are some links to photos:



Fortunately, the Autopilot seems OK. Can anyone tell me what may have caused this? And do you think it could have been the new cell? I think I'm stuck replacing the cell and cord at my expense. The cell has a two year warranty but I'm not sure if they will consider this a manufacturing problem...
Bill
 

JasonLion

TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
37,880
Silver Spring, MD
That was caused by a bad electrical connection between the cell and the cord. The bad connection heated up and melted/burned the connections.

The bad electrical connection was probably because of a bad fit between the cell and the cord, which could be caused by a design defect in the generic replacement cell, or the cord might simply not have been fully seated/pushed down far enough. There is some chance that it could have been caused by existing corrosion in the cable connector, which would be a defect in the cable, but that is far less likely.
 

Poolsean

TFP Expert
Apr 15, 2007
1,462
Ft Lauderdale, Florida
Just to note, the cell in the photo is a GENERIC replacement cell and is not recommended by AutoPilot, or most other Salt Chlorine Generator manufacturers.
We have noticed that the spacing of the cell prongs of the Generic cells are not consistent and can cause the damaged show, and as described by Jason.

When cells are replaced, it is recommended to replace the cell cord too. I notice that there isn't a red plug located in the outer hole (either side is acceptable). This prevents water or moisture from entering the cell plug, which also can cause this damage.
 

Billhev

New member
Aug 8, 2010
2
Thanks for the quick answers JasonLion and Poolsean. Just to clarify, I installed this the first week in April and have been using it with no problems all season. The red plug was installed in the third hole, but was ejected when the cord heated up. I'm thinking that the cord may have let some water (we've had a couple of really bad storms lately) in around the top of the plug which then provided a cross connection between the two posts. Just a theory though. Poolsean, you've seen this same problem with other generic cells? Any experience with this particular one? I know you usually get what you pay for but the difference between $580 for OEM and $299 for this one seemed like a fair deal.
Bill
 

jparr

Well-known member
Jun 12, 2010
65
Strannik said:
it can also be caused by corrosion in the lead connectors.

generally anything that prevents good electrical contact will cause that
...and along those lines, would using dielectric grease on the SWG cell contacts be a good idea? Seems like it'd do a great job of keeping moisture out and preventing corrosion.
 

Strannik

TFP Expert
LifeTime Supporter
Jul 24, 2007
874
Brisbane, Australia
it would be a bad idea, cause if it makes it onto mating surfaces you'll end up with the picture above, as it's non-conductive.

what you can use instead is Carbon Conductive Grease (or silver conductive grease). that will both protect it from corrosion and enhance the contact

Autochlor uses that on their commercial cell connectors that pump through hundreds of amps.
 

Poolsean

TFP Expert
Apr 15, 2007
1,462
Ft Lauderdale, Florida
Sorry, not enough history to say that I've seen this on a regular basis. However, we did purchase several cells to evaluate and noticed that the spacing of the prongs were not to our specs, and as I mentioned, will cause problems. Also noticed that the spacing between the blades were wider then our factory cell, which would also cause the power supply to run at a higher voltage than normal.
 

aimpulsive

New member
Sep 26, 2010
1
I had the same problem with my Autopilot.

I have had the unit for about three years, without problem (except that the temp sensor says it is "bad", which has been going on all summer).

A few days ago I noticed the pool had no chlorine. When I checked the Autopilot control head it seemed fine and indicated no errors or questionable conditions. But, when I checked the cell the cable looked like it had exploded where it connected to the cell. It had a black tarry substance all over it and the cell's connecting pins were blackened, with the middle of the three burned badly. It actually melted the plastic from around that pin.

All three pins were covered with soot and tarry junk, although all but one came clean after a bit of sanding and scrubbing. The middle one was damaged slightly and the metal is pitted, and as noted the plastic around that one is melted somewhat.

I am using the Autopilot Digital with a SC60 cell.

Any ideas as to what could cause this on an otherwise good unit that is fairly new?
 

Bama Rambler

Mod Squad
TFP Expert
LifeTime Supporter
Jun 22, 2009
23,062
SouthWest Alabama
Any electrical device can corrode and those that carry Direct Current are more susceptible to it than those that carry AC.

Given the application and location of most SWCG cells it's not hard to believe that corrosion can and will occur. Those connectors should be taken apart and cleaned and lubed with dielectric grease at least once a year.
 

Ohm_Boy

TFP Expert
May 1, 2007
1,344
Orlando, FL
The cell connector post material can also play into it. Dissimilar metals tend to set up electrolysis and corrode. All things combined, the variance in spacing and size, chlorine and salt exposure, moisture, any oxidization on the contacts, and any surface corrosion will tend to reduce the contact conductance. I mean, increase the resistance. Wait.. they're both right.
Anyway, bad connections are like water leaks. Left to themselves, they tend to get worse.

-Mho, the Ohm Boy.
 

Floater123

New member
Nov 20, 2010
1
I have been using NO OX ID (http://www.sanchem.com/aSpecialE.html) which is a conductive grease and electrical contact lubricant. I use it sparingly and apply it with a Q-tip. The plug comes of the cell easily for cleaning and reattaching is just as easy. This stuff stops corrosion before it starts. Chances of shorting and arcing are eliminated as long as the plug is seated correctly.

BZB
 

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