Hi everyone!
I'm working on a project, where my electronics run off of 4.2V Li-ion batteries. The electronics are a couple of IC's and a 12V motor.
The IC's are powered by an LDO that drops the 4.2V to 3.3V, and the 12V is run by boosting the voltage from 4.2V to 12V.
My problem is that the efficiency isn't great when we look at the boost IC.
The reason I have a 4.2V battery pack (1S3P) is because I have a small solar panel that slowly charges the battery pack.
To solve the efficiency problem, I have come up with an idea of switching the wiring of the battery pack. Let me explain:

This is the wiring I have come up with (but for 1S2P it would be the same for 3P,4P ect).

This would be the wiring when I need 4.2V to power the electronics (which are in sleep mode) and the batteries are charging.

This would be the wiring, when I switch off SW1 and SW3. The idea is that the electronics would be powered still off-of the first 4.2V battery, and the motor would be connected to the new 8.4V (or in 3S 12.6V) source.
Of course the switching order is crucial, so we don't short the batteries.
Is this a good solution, or should I go with the old solution (boosting the voltage for the motor)

?
The motor would draw around 2A-3A.
Edit: the motor would be on for max 10s and would be switched over to the second image. So the 8.4V/12.6V source would be avaiable for only 10s.