Battery (primary - alkaline/coin)
Battery
Single-use non-rechargeable batteries that store chemical energy and convert it to electrical energy. Common in portable devices.
Schematic symbol
Battery / cell
How battery (primary - alkaline/coin) appears in a circuit diagram.
Types & variants
Key specs
Voltage
Volt (V)Nominal voltage (e.g., AA: 1.5V, 9V: 9V, CR2032: 3V). Drops as battery depletes.
Capacity
mAh (milliamp-hour)Total charge stored. Higher = longer life. Varies by size and chemistry.
Size
mm/inchesPhysical dimensions (e.g., AA: 50.5 × 14.5 mm, CR2032: 20 × 3.2 mm).
Chemistry
-Alkaline (common), lithium (long life), zinc-carbon (cheap), silver oxide (precision).
Markings
Voltage printed on battery (e.g., '1.5V', '9V', 'CR2032'). May have date code, manufacturer, and capacity.
Standard values
AA/AAA: 1.5V, 9V: 9V, Coin cells: 1.5V (alkaline) or 3V (lithium). Capacities: AA ~2000-3000mAh, CR2032 ~220mAh.
How to choose
1) Match voltage to device requirements. 2) Choose size that fits. 3) Consider capacity for runtime needs. 4) Lithium for extreme temps/long life, alkaline for general use.
Pinout & package
2 terminals (+ and -). AA/AAA: protruding top (+) and flat bottom (-). Coin cells: marked side (+) and plain side (-). 9V: snap connectors.
Example circuits
- Powering remote controls
- Backup power for RTC modules
- Portable LED flashlights
- Small motor drives
- Powering IoT sensors
Common failures
Voltage drops below usable level, internal corrosion causing leaks, physical swelling, complete discharge (dead battery). Signs: device doesn't turn on, dim output, visible corrosion.
How to test
Set multimeter to DC voltage. Place probes on battery terminals (+ to red, - to black). Measure voltage. Compare to nominal voltage (e.g., AA should read ~1.5V when fresh, drops as it depletes).
Substitutes
Same voltage and size batteries. Lithium can replace alkaline in same size for longer life. Avoid mixing old/new batteries or different chemistries.