As I see on the wiki page, these motors do not come with an encoder.
Here are the motor specs:
Model: JGB37-520 DC Geared Motors
Rated voltage: 12V
Rated current: 0.3A
Locked-rotor current: 1.4A
Rated torque: 2.4kg.cm
Locked-rotor torque: 10.4kg.cm
Rated output power: 1.3W
No-load speed: 66±10%RPM
Rated speed:51±10%RPM
Motor size: 37*52mm
Output shaft size: 6*15mm
Single motor weight: 145g
Regarding the battery:
It uses 3 x 18650 in series (not included) as the power for the robot, can output 5V and 3.3V for external devices.
Onboard INA219 chip for detecting voltage/current information and so on. Support charging and power output at the same time,
allowing uninterrupted development.