As for the battery life on Kobos? The only Kobo that has shown relatively short battery life is the Kobo Sage. Perhaps having the smallest battery (1,200mAH) of Kobo's ereaders—by comparison, the Kobo Libra Colour has a 2,050mAH battery—and largest screen along with a CPU that is noted for poor power management has something to do with that.
OTOH, I get ~16 hours of reading on my Sage and courtesy of it's USB C port and small battery, the charge time is less than an hour. Much like the older Kindle Oasis which needed a power cover for decent reading life, the Sage has an optional battery cover but for most people the weight made it a non-starter. I went with a 10,000mAH power bank which allows me to charge my Sage multiple times and was quite a bit cheaper than the Kobo power cover not to mention it allows me to charge my other devices if needed.
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