A button cell (disc or watch battery) may come in various sizes.
Designations:
(1) first letter - the electrochemical system
(2) second letter - R for round
(3) first numbers - diameter code of 1 or 2 digits (diameter in mm rounded down)
(4) last 2 numbers - height number (height in mm times 10)
(5) suffix letter - electrolyte indicator
|
Positive Electrode |
Negative Electrode |
First Letter |
|
carbon monofluoride |
lithium |
B |
|
manganese dioxide |
lithium |
C |
|
copper oxide |
lithium |
G |
|
manganese dioxide |
zinc |
L |
|
mercuric oxide |
zinc |
M (no longer used) |
|
mercuric oxide |
zinc |
N (no longer used |
|
oxygen |
zinc |
P |
|
silver oxide |
zinc |
S |
|
Nominal Diameter |
First Numbers |
|
4.8 mm |
4 |
|
5.8 mm |
5 |
|
6.8 mm |
6 |
|
7.9 mm |
7 |
|
9.5 mm |
9 |
|
10 mm |
10 |
|
11.6 mm |
11 |
|
12.5 mm |
12 |
|
16 mm |
16 |
|
20 mm |
20 |
|
23 mm |
23 |
|
24.5 mm |
24 |
Exception: LR44/SR44 = alkaline silver, diameter 11.6 mm, height 5.4 mm
|
Electrolye |
Suffix |
|
organic |
<none> |
|
potassium hydroxide |
P |
|
sodium hydroxide |
S |
The suffix W indicates that the battery meets the international standard for a watch battery.
