Some data. Over the past year, I've been getting between 5 and 9 hours of use, depending on how much WiFi I use.
Now, I typically run in Airplane mode -- and, during the day, with brightness at 1/4. (One gets used to lower brightness pretty quickly!). At night, I use it for ebook reading with colors inverted and the backlight barely on.
When I turn on WiFi to fetch news, the battery can drain 8-14% in only 2-3 minutes of use!
It is a shame as it undermines an otherwise fine device.
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BIG TIP: One of the gurus in the Apple forum recommended leaving it charging for a full 6 hours-- well past the point it first gets to 100%. The IPT 6 charges quickly, but apparently the gauge is off-- it needs to be charged longer, much longer than first hitting 100%.
That has helped-- some WiFi sites now barely register on battery life.
Yeah battery behaviour on the ipod touch 6 is messy. It charges quickly but also discharges quickly,i recently found that when the device hits 20% battery left i still can use it for an hour more watchig youtube videos so i'm calibrating it currently.