According to its specs, the MicroBot has a battery life of about one year. The battery is rechargeable, using a regular 5V charger with a micro USB connector.

Battery charging circuit

Charging IC

Transistor to control the red and green LEDS next to the USB port, indicating whether or not the battery is fully charged

Battery protection circuit

These types of ICs are used to “sense” the current

When the specified current limit has been reached they trigger a switch that will break the current path to the battery. The switch that is triggered in this case is a Dual N-Channel Enhancement Mode Power MOSFET, in this case the 8205A