Data logging, collecting and sending them once a day

Have you considered FRAM (Feroresemot Random Access Memory) It's similar to Static random-access memory, only with a ferroelectric layer instead of a dielectric layer. This gives it stable handling (the bytes you write are non-volatile) with dynamic responsiveness (you can write them very fast!). Some of the advantages I see in FRAM are high speed reading and writing, non-volatile storage (it remembers its contents without needing power or battery backup), virtually unlimited read / write cycles - you can't wear it out unlike some other types of non-volatile memory. To get started try this link: Adafruit SPI Non-Volatile FRAM Breakout - 64Kbit / 8KByte : ID 1897 : $5.95 : Adafruit Industries, Unique & fun DIY electronics and kits There board has a write enable input so you can lock it down and read it on another machine without worry about trashing the date. This response is to help you get started in solving your problem, not solve it for you.
Good Luck & Have Fun!
Gil