I'm quite new in electronics. But I want to build an autonomous device logging on a sd card the temperature outside. My idea is to reproduce a standalone arduino, with chip pre-programmed on my arduino uno board, and to power it with 2 3.7V batteries coupled to some solar cells delivering less than 4-5 V. My question is about how to couple batteries, solar panel and arduino to both power arduino and allow battery charging. (Arduino is not important to me, it could be anything needing power).
I dismantled a garden light and see that solar panel was basically connected to batteries with a simple diode. But I also viewed that dedicated drivers exist to put between batteries and solar panel.
My understanding is that driver is probably a better solution for battery longevity, but diode solution is working well too. Am I right ? Do you have a deeper understanding of this, or a previous experience to share ?
Thank you !