Button Cells

Silver oxide button cellshave a rated voltage of 1.55 V and are leak-proof. Since these batteries provide constant voltage over time, they are preferably used in wristwatches. Another distinguishing feature within the group is the current carrying capacity:

Low drain: Low current carrying capacity
in these button cell types, caustic soda is used as electrolyte. The cells are very leak-proof and are used, for example, in watches.

High-drain: High current carrying capacity
in these button cell types, calileye is used as electrolyte. These cells are suitable for photo and remote control applications.

Lithium button cells have a nominal voltage of 3.0 volts and are used wherever a power supply has to be ensured for a long time. For this reason, these button cells are used e.g. as backup batteries in computers or also in sensors of weather stations and in car radio keys.

Since lithium button cells are partly soldered to circuit boards, the cells are also available with welded soldering tags. Alternatively, you can use a button cell holder. In this case, commercially available button cells can be used without soldering tags.

Zinc-air button cells have a nominal voltage of 1.4 volts and have an enormous energy density. The button cells are supplied with a sticker that is only removed shortly before use. Only then can the air required for the chemical processes enter the cell and activate the battery. Zinc-air batteries are primarily used in hearing aids.

Mercury button cell information

The ban on hazardous substances (RoHS Directive, published in January 2003 and in force on July 1, 2006) means that mercury button cells are no longer allowed to be sold and have thus completely disappeared from the market.
 

If a button cell is labeled CR1620 , the type designation indicates the following:

C: Letter of identification for a lithium cell (S=silver oxide and L=alkaline)
R: Letter of identification for round cell
16: Diameter of button cell in mm
20: Height of button cell in 1/10 mm (corresponds in this case to 2 mm)

Unfortunately, there is no uniform type designation for button cells. Rather, there are the different manufacturer's designations, which are also partly mixed together. Even if a SR44 and a LR44 have the same dimensions (Ø x H = 11.5 x 5.4 mm), the SR 44 is a silver oxide button cell and the LR44 is an alkaline button cell.

It is possible to replace an empty alkaline button cell with a new silver oxide button cell. The slightly higher nominal voltage of 0.05 V is used by most devices. In case of doubt, the manufacturer of the device can ask to what extent a replacement with silver oxide button cells is permitted.
 

A button cell comparison table is only helpful if it is known exactly for which button cell a replacement is being sought. It becomes difficult if the empty/defective button cell is not labeled or the labeling is no longer legible .

Measuring with a commercially available metal sliding caliper is also not a good idea, since a short circuit is fabricated at the latest when measuring the height of the button cells. Either one takes a plastic sliding caliper or even better a button cell stencil. This allows you to quickly determine which button cell is involved and find replacements using the comparison table.