The equivital SEM has an internal Lithium ion battery. Recharge time from flat is approximately 1 hour to full charge. The battery life depends on the physiological parameters being measured as well as the data transmission mode being used. For real-time monitoring of standard parameters offered, the battery life expectancy for full charge is approximately 13.5 hours. For additional battery life an external battery pack can be added (connects to the sensor belt and fits into a second pocket on the sensor belt), which extends the battery life by up to 3 times.