The positive terminal is the end marked with a plus sign (+) and is usually color-coded red; on most common batteries, the positive end is the top or the raised contact, while the opposite end is negative. Always check the markings on the specific battery you’re using, as some specialty packs may differ.
Identifying polarity by battery type
Here are the standard cues you’ll encounter with the most common batteries in everyday devices.
- Plus sign (+) printed on the battery near the positive terminal
- Red color coding at the positive end (a common convention in consumer products)
- For cylindrical cells (AA, AAA, C, D): the positive terminal is the raised metal nub on the top; the negative terminal is the flat bottom
- For coin/button cells (CR2032, LR44, etc.): the positive terminal is the flat top surface; the negative terminal is the outer rim of the can
- For lead-acid automotive and other large batteries: the positive terminal is usually marked with a plus (+) and often covered in red plastic; the negative terminal is marked with a minus (-) or is indicated by black coloration
Always consult the battery’s labeling or the device manual if you’re unsure, especially with unfamiliar chemistries or specialty packs.
Special cases and notes
Some configurations require extra care beyond these standard markings. For example, rectangular 9-volt batteries have two terminals on the top surface; polarity is typically indicated on the casing or by device documentation. If markings are unclear, a multimeter can help verify which terminal is positive by measuring the potential relative to the other terminal.
When mounting or replacing batteries, ensure correct orientation to prevent device damage, leakage, or safety hazards.
Safety considerations
Correct polarity is essential for safe operation and performance. Keep terminals from touching to avoid short circuits and never connect the wrong end to a power source.
- Avoid mixing battery chemistries in the same device unless the manufacturer allows it
- Inspect batteries for damage before use and dispose of damaged cells according to local regulations
By following these guidelines and reading manufacturer markings, you can quickly and safely identify the positive terminal across most common battery types.
Summary
The positive terminal is the end labeled with a plus sign (+) and often colored red. On cylindrical cells, the top raised contact is positive; on coin cells, the top surface is positive; on car batteries, the positive terminal is the red-marked end. Always verify markings on the specific battery and device.