It’s great to see you exploring different platforms for your electronics inquiries! Regarding your setup with the variable boost converter, 18650 batteries, and the 12V LED strip, your analysis is on the right track.
The boost converter indeed stabilizes the output at 12V irrespective of the input voltage. In your scenarios, both setups - series and parallel configurations of the 18650 batteries - should effectively power the LEDs at 12V through the boost converter.
Your assumption about the parallel circuit draining faster than the series circuit due to the boost converter’s behavior is accurate. Since the parallel circuit offers half the voltage but doubles the current capacity, it will indeed discharge quicker compared to the series circuit.
Concerning the choice between parallel and series setups, there are trade-offs. The series circuit might experience fewer losses through the boost circuit due to its higher efficiency with higher input voltages, potentially reducing heating issues. However, as you mentioned, charging cells in series isn’t feasible with your TP4056 board, limiting your option to the parallel configuration.
Given your charging constraints, sticking to the parallel configuration seems more practical for recharging purposes. While it may drain faster, using the parallel setup is compatible with your charging board and allows for easier recharging.
I noticed your edit about the TP4056 board being compatible only with parallel charging, which aligns with your previous discovery. It’s a crucial factor to consider in maintaining the functionality and longevity of your battery setup.
If you want more insights on the efficiency differences or additional alternatives for charging in series, I have an informative post on converter types that delves into various setups and charging considerations, which might offer further clarification for your project.
Feel free to explore and let me know if there’s anything specific you’d like to dive deeper into!