A question I’m often asked is what the battery life is like for particular e-ink tablets.
To answer this, since 2024, I’ve carried out battery tests on all the e-ink tablets I’ve used.
Method
To test the battery, I record how much percentage of battery is used for certain tasks (note-taking, reading) and with Wifi/Bluetooth on/off, and (if it has one) the frontlight turned off, turned on full, and turned on at the middle range. You can find this data on each of my review pages in the ‘Battery‘ section.
My process is:
- Go into the power settings and turn off sleep/power timeouts. I also make sure the latest firmware is installed, so that the device doesn’t try to update during testing.
- Get a baseline measurement by turning off Wifi/Bluetooth and the frontlight and recording how much battery percentage has been used after one hour.
- Turn on Wifi/Bluetooth and leave it again for another hour to see how much battery percentage has been used (the difference between the measurements in steps 2 and 3 is the number I use for how much additional battery will be used when the Wifi/BT is turned on)
- If the device has a frontlight, I turn off the Wifi/Bluetooth and do the same hourly test twice more with the frontlight turned on the medium setting, and full setting (again the difference between the baseline measurement and these results is recorded)
- Next, I turn off Wifi/Bluetooth and the frontlight, and read a book for an hour using the native reading app, recording how much battery is used. I will admit that I have sometimes used the Auto-Page-Turn feature that is available on some tablets and just left it turning a page every minute-or-so for an hour.
- Finally, I use the native note-taking app for an hour (again, Wifi, Bluetooth and the frontlight are turned off during this test). I mostly spend my time writing down my thoughts about the device in preparation for my full review. One thing I always do during this test is shade/colour-in a whole page black because this helps to indicate any performance lags when there are a lot of strokes on-screen, as well as highlight any dead pixels, and issues with writing at the edges of the screen. I also play about with the options on the toolbar as well to familiarise myself with the tablet’s capabilities.
Using this data, I calculate the typical number of days worth of battery you might expect from each full charge. I’ve recently changed the way that I calculate battery life due to some flaws with my previous method. There are now two battery performance tables. The first ranks the tablets according to how much battery life you could expect from three hours of note-taking and three hours of reading per day. For tablets on this table that do not have a frontlight, it is assumed that the frontlight has been turned off for the duration. The second table is only for tablets that have an integrated frontlight and additionally assumes that the frontlight has been turned on to a medium setting for the six-hour duration. I assume wifi is turned off, but include this data in the individual reviews so that readers can make their own calculations if they are likely to need a permanent connection to the Internet.
Of course, these tests will not be 100% accurate. Typical use for you may not be the same as I’ve defined above (you may use apps, Wifi or the frontlight more/less). Also, when I came to do these tests, some of the tablets had been in my possession for years, so the battery could have deteriorated a bit. Another caveat is that newer firmware versions could affect battery life either positively or negatively. But I feel it gives a good general idea for comparison purposes.
Battery life (no frontlight exists or frontlight is always turned off)
Assumes 3 hours of notetaking and 3 hours of e-reading per day
Battery life (frontlight is constantly turned on to a medium setting)
Assumes 3 hours of notetaking and 3 hours of e-reading per day, with the frontlight turned on to a medium setting for the 6-hour duration. Only tablets with frontlights are listed.
