Battery GARMIN replacement for Garmin Forerunner S1, Forerunner S1W(0)

What is the run time of GARMIN 361-00064-00 battery?

GARMIN 361-00064-00 have two main ratings on them: Volts and Amperes. Because size and weight of batteries is limited when compared to larger batteries such as car batteries, most companies show their ratings with Volts and Milliamperes. One thousand Milliamperes equals 1 Ampere. When buying a battery, select batteries with the most Milliamperes (or mAh). Batteries are also rated by Watt-Hours, perhaps the simplest rating of all. This is found by multiplying the Volts and the Amperes together.