How do i find suitable power source given component specs
You also need to consider the operate time and the normal run loading.

If the life time is short.
2 LiPo in series is OK.
Start current = 2.8*4 = 11.2A is quite large?
18650 Lipo can support 20A.

2 Lipo in series supply max 8.4V which is over the operate voltage?
Use PWM to drive.