Silver vs alkaline button cells

I purchased a new digital caliper recently (no, they are NOT vernier calipers, though modern usage seems to have misused the term vernier to the point of it having no value).

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A pic of the back reveals their recommendation for a battery, it is in the upper right corner of the pic “Battery 1.55V”. This is really subtle and a departure from previous practice of marking them more clearly SR44.

The nominal voltage of a silver button cell is 1.55V, an alkaline is 1.5V.

This might seem to be splitting hairs, but the discharge characteristic of the cell types is quite different. (Duffy 2012) showed that silver cells give longer life, and cheaper life given the voltage at which the display starts flashing (1.42 – 1.45V typically). Yes, they work on alkaline cells, but within a few weeks the display is flashing to warn that the results are unreliable due to low battery voltage.

So, the seller of the calipers who advertised one silver cell and one spare (about $4 worth), and delivered two LR44 alkaline cells (about $0.40 worth) has cheated the buyer out of $3.60.

So, when you go to buy cells, your Chinese product makes it confusing.

IMG_1595

The above cell is actually an alkaline (it is it marked LR44 on the cell), but it claims to replace a SR44W silver cell. It does dimensionally, but it is not equivalent electrically (the discharge characteristic mentioned above).

In the blatantly dishonest world of eBay, sellers advertise alkaline cells as silver cells, and then when their lie is exposed they claim “sorry you misunderstood, cell is silver in colour”. It is not just the sellers who compete with each other to tell the same lies, eBay benefits as they make money out of the selling.

References

Duffy, O. Nov 2012. Button cells in digital calipers and the like. http://owenduffy.net/files/SilverAlkalineCells.pdf.