Why does my coin battery show low voltage when measured with a voltmeter?

The result varies depending on the type of voltmeter:

• Analogue meter (stylus type): as this type of voltmeter can only register higher amounts of voltage, measuring coin batteries may not be accurate. 
• Digital meter (numeric indication type): these can register lower currents, so measuring a coin battery may be more accurate. However, it does not necessarily indicate the exact remaining life span of the battery.

For an accurate result, be sure to use a voltmeter that corresponds to the battery type. Use a meter with more than 1 megaohm input resistance for alkaline button batteries. Use 10+ megaohm for lithium batteries.