I’ve used a lot of different configurations of Arduino-related gear as datalogging utilities. So here’s a comprehensive guide on what’s possible, how to set up stuff and on what you can expect regarding accuracy, battery life and logging speed.
(However, please keep in mind that I’m neither particularly skilled with electronics nor programming and other’s know a lot more on this than I do. I’m particularly grateful that Ed Mallon provided a link to this paper he coauthored with Patricia Beddows in the comments – the work and knowledge they put into it is just amazing)
My Arduino Uno with the datalogger shield both temperature and brightness sensors connected. I used a normal smartphone charger to power it for more than 3 days and placed it in this fireproof baking tray since I felt somewhat unsure about having it running unattended.