Coin Cell Battery Code Decoder (CR2032 …)

Understanding the coin cell battery code decoder — concept and principle

Coin and button cells carry a short code such as CR2032, CR2025, SR626 or LIR2032. This decoder reads the letters and digits to tell you the chemistry, nominal voltage, diameter and thickness, so you can find a compatible replacement for a watch, car key, scale or motherboard.

How it is calculated

The code is split into a letter prefix and digits.

• First letter: chemistry. C = lithium manganese dioxide (3 V), B = lithium carbon monofluoride (3 V), L = alkaline (1.5 V), S = silver oxide (1.55 V). LIR is a common maker prefix for rechargeable lithium-ion cells (about 3.6–3.7 V).
• R: round shape.
• Four digits: first two = nominal diameter in mm, last two = thickness in tenths of a mm.
• Three digits (watch cells): the first digit is a diameter class (6 = 6.8 mm, 7 = 7.9 mm, 9 = 9.5 mm) and the last two the thickness in tenths of a mm. Legacy names such as LR44 (11.6 × 5.4 mm) come from a table.

The principle

IEC 60086 gives battery designations a structure: a letter for the electrochemical system, a letter for shape, and a size code. For round lithium coin cells the size code is literally the dimensions, which is why CR2032 can be decoded without a table. The nominal voltage follows from the chemistry, not the size: every CR cell is 3 V whether it is 12 mm or 24 mm across. Capacity, however, grows with volume, so a thinner cell of the same diameter stores less energy.

Worked example

Default: CR2032.

1. Prefix "CR": C = lithium manganese dioxide, R = round; nominal 3 V.
2. Digits 2032: first two "20" = 20 mm nominal diameter.
3. Last two "32" = 32 ÷ 10 = 3.2 mm thickness.
4. Result: 20 mm × 3.2 mm, lithium manganese dioxide, 3 V.

How to read the result

A replacement must match the voltage and the diameter; thickness decides whether contacts touch properly. CR2032, CR2025 and CR2016 share 20 mm and 3 V but are 3.2, 2.5 and 1.6 mm thick, with capacity falling in that order. Some devices hold two thin cells in place of one thick cell, which doubles the voltage, so follow the device's marking.

Common mistakes

• Putting a rechargeable LIR2032 in place of a CR2032: its higher voltage can damage devices not designed for it.
• Using a thinner cell with a folded piece of foil; contact may be intermittent.
• Reading the first digit of a three-digit code as millimetres: SR626 is 6.8 mm wide, not 6 mm.
• Ignoring suffixes such as SW (low drain) or W (high drain) on watch cells.

FAQ

Frequently asked questions

Can I use CR2025 instead of CR2032?

Same voltage and diameter, but 0.7 mm thinner and lower capacity; it may fit loosely and will run out sooner.

What is the difference between LR44 and SR44?

Same size; SR44 (silver oxide) holds a steadier voltage and is preferred for watches and meters.

How long does a CR2032 last?

It depends on the device's current draw; low-drain devices such as motherboard clocks often run for years.

Sources: IEC 60086-1 Primary batteries – Part 1: General · IEC 60086-2 Primary batteries – Part 2: Physical and electrical specifications