I'm trying to determine if I need to rethink my circuit for a solar + Li-Ion powered Arduino. Basically a solar powered module with 3.7V Li-Ion backup for night / clouds (to be charged during the day). Being my first go at utilizing solar + rechargeable batteries, I've been looking at this  instructable, specifically Part 6.
Essentially my circuit is a solar panel connected to a TP4056 Li-Ion charge controller's IN connectors. I have my BAT+ connected to a 3.7 Li-Ion + terminal and the IN+ boost regulator to boost up to 5V, and likewise with the negatives. My boost regulator then connects to the Arduino.
My worry is that with all these in the same circuit, the charge controller will never stop outputting power to the regulator in order to run the Arduino, which could then cause anything unused to flow into the Li-Ion battery, possibly overcharging it.
Is this a legitimate possibility, or is there just something I've yet to learn more about?