Note: Modified Topic title.
AFAIK, temperature drops can effect the bond of the coating to the plates. The two have slightly different expansion and contraction rates. While Ruthenium is a metal, Ruthenium Oxides are crystalline and is used to prevent corrosion. Because it's crystalline, the formation of micro cracks in the coating is possible when stressed by the differences in the expansion and contraction rate.
While this may not immediately create a failed cell, and in fact, usually doesn't, when the cell is brought back on line, the flow of water through it is generally somewhat turbulent. This turbulence will generate some additional eroding friction and vibrations. Guess what happens to the coating's micro cracks? They may grow or expand.
Bringing in the cell in the winter may reduce the some of the stresses a cell's coating faces. As long as the cell isn't tossed in the bottom of a closet where the kids may bounce it around looking for their missing glove, the coating will not face the increased brittleness of it's crystalline nature vs. expansion/contraction characteristics of the plate metal, regardless of the small amounts of stresses involved.
Larger and more important factors in cell life are chemical and friction erosion. But everything that we can do to extend our ROI, should be.
I did try to get real numbers with respect to hardness, brittleness and temp relations on Ruthenium Oxide but was not able to find any.
I do have several customers with older cells (i.e. greater than 5 years) that have been bringing in the cell diligently. They also watch their chems.
PS/Side Note: Any idea why Autochlor's support page says:
How does the AutoChlor system remove calcium build-up on pools?
By extracting excess hardness (calcium etc.) from the water during the electrolytic process. This improves the feel of the water, protects the pool equipment and saves you money.